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Effects of Eight Chinese Style Cuisine Methods on Polycyclic Aromatic Hydrocarbons, Trans-Fatty Acids and Nitrite of Beef ZHANG Lan, GAO TianLi, LIU YongFeng, ZHAO Jing, LIAO Jing, KU Ting Scientia Agricultura Sinica    2017, 50 (6): 1126-1138.   DOI: 10.3864/j.issn.0578-1752.2017.06.013 Abstract （412）   HTML （2）    PDF （615KB）（577）       Knowledge map    Save 【Objective】The purpose of this study is to select the processing techniques of beef with less harmful substances from the steaming, boiling, braising, broiling, frying, pan-frying, drying and pickling eight traditional Chinese cooking process. The result of the present study will also provide a theoretical basis for consumers to choose a reasonable cuisine method with less harmful substances.【Method】By adjusting the temperature and time of broiling, frying and pan-frying, the contents of polycyclic aromatic hydrocarbon (PAHs), trans-oleic acids (C18: 1 trans-9) and nitrite are compared, so that the optimum cooking conditions of broiling, frying and pan-frying were selected. On this basis, the eight Chinese style culinary arts were comprehensively analyzed so as to select the optimum cooking methods, and the indexes were determined by high performance liquid chromatography (HPLC) external standard method, gas chromatography-mass spectrometry (GC-MS) external standard method and spectrophotometry, respectively.【Result】Four PAHs including pyrene, benzo[a] anthracene, chrysene and benzo [k] fluoranthene were detected in control group. The treatments of broiling at 160-180℃ were better, and the contents of the five PAHs were lower. The contents of PAHs were lower in process of frying for 3-4 min and pan-frying for 2-3 min. Among the eight Chinese style cuisine methods, the processes of frying and pan-frying had the highest number of PAHs species. The benzo [b] fluoranthene content in processed of frying and pickling were higher. The chrysene contents in process of steaming and pan-frying were higher, the benzo [b] fluoranthene contents in processes of broiling, frying and pan-frying were higher, the contents of benzo [k] fluoranthene, benzo[a] pyrene, Dibenz [a, h] anthracene in frying and pan-frying treatments were higher. The C18:1 trans-9 content in the process of frying for 3min and pan-frying for 2 min were lower (P＜0.05). The effect of broiling temperature on the content of C18:1 trans-9 was not significant. The C18:1 trans-9 contents in frying and pan-frying treatments were higher among the eight Chinese style culinary arts (P＜0.05). The nitrite content in the process of broiling at 160℃ and 180℃ were lower, and that in treatments of frying for 3 min and pan-frying for 2 min were the lowest (P＜0.05). The nitrite contents in treatments of frying, pan-frying and pickling were higher among the eight Chinese style culinary arts (P＜0.05).【Conclusion】The content of three harmful substances in beef that being broiled for 40 min at the temperature of 160℃, at the temperature of 226-228℃ fried for 3 min and pan-fried for 2 min were lower compared with the control group. A comprehensive analysis revealed that the beef processed by steaming, boiling, braising and drying contains less hazardous substances. Reference | Related Articles | Metrics

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Effect of Extraction Time on Characteristics of Gelatin and Secondary Structure of Chicken Bone Protein YUE JianYing, WANG JinZhi, ZHANG ChunHui, DU GuiHong, XU Xiong Scientia Agricultura Sinica    2017, 50 (5): 903-912.   DOI: 10.3864/j.issn.0578-1752.2017.05.013 Abstract （379）   HTML （2）    PDF （393KB）（680）       Knowledge map    Save 【Objective】Hot-pressure extraction was utilized to prepare chicken bone protein (CBP) to study the effect of extraction time on gelatin properties. The study was expected to provide a reference for the preparation technology of edible gelatin by using chicken bone by-products. 【Method】After being adjusted to the same concentration of protein, CBP at different extraction times were incubated at 4℃ to form gelatin. The content of total soluble substance (TSS), crude protein and hydroxyproline (Hyp), secondary structure of protein and distribution of molecular weight (MW), as well as color of gelatin and gel strength were studied. Furthermore, correlation analysis between indexes of CBP was also performed to establish possible linkages between physicochemical properties and gelatin properties of CBP.【Result】The results showed that hot-pressure extraction time had a significant effect on the yield of CBP (P＜0.05), leading to the variable structure of protein and consequently affected the properties of gelatin made by CBP. The contents of TSS, crude protein and Hyp were increased significantly during extraction (0-120 min) (P＜0.05). The result of MW distribution suggested that protein experienced dramatic degradation from 40 to 120 min (P＜0.05). The proportion of MW between 10 and 30 kDa decreased from 59.82% (40 min) to 13.99% (120 min) while the ratio of MW ＜10 kDa increased from 35.46% (40 min) to 86.01% (120 min). In addition, the extraction time caused the denaturation of protein and thus leading to the change of secondary structure. The CBP was composed of 100 percent of α-helix (0-40 min), and then β-sheet emerged at 60 and 90 min (9.9% and 17.6%, respectively) but disappeared at 120 min, which indicated that the secondary structure of protein experienced transformation during extraction. Results of CBP gelatin properties suggested that CBP at 0 min could not form a gelatin and thus had no gelatin properties. Gel strength at 20, 40 and 60 min was at same level and better than CBP gelatins of 90 and 120 min. In addition, transparency of CBE solutions was significantly impacted by extraction time, which increased sharply during hot-pressure extraction (20-120 min) (P＜0.05). Meanwhile, extraction time significantly affected the color of gelatins (P＜0.05) and gelatin at 40 and 60 min met the requirements of high lightness, low yellowness and high whiteness. However, water holding capacity was insensitive to the extraction time (P＞0.05). Correlation analysis showed that the content of Hyp, degradation of protein were considerably related to gelatin properties (P＜0.05).【Conclusion】In conclusion, extraction time could significantly affect the gelatin properties prepared by CBP at different extraction times. Given yield of protein, color of gelatin, gel strength, etc., CBP extracted at 40 min and 60 min were better proper for preparation of gelatin. Reference | Related Articles | Metrics

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Metagenomic Analysis of Bacterial Phases of Catfish Fillets Under Different Storage Conditions ZHU YingChun, WANG Yang, FAN XiaoPan, MA LiZhen, WANG KaiLi Scientia Agricultura Sinica    2017, 50 (5): 913-923.   DOI: 10.3864/j.issn.0578-1752.2017.05.014 Abstract （345）   HTML （4）    PDF （983KB）（872）       Knowledge map    Save 【Objective】The objective of this experiment is to analyze the dynamic changes of bacterial phase of catfish fillet stored under different storage conditions, evaluate the effect of natural preservative on the special spoilage bacteria. 【Method】There were 8 groups in this experiment including fresh catfish (Calarias gariepinus) fillets (CK0), AP (air-package) catfish fillets stored at (4±1)℃ for 4 and 7 d (AP4, AP7), MAP (modified atmosphere package, 60%CO2/40%N2) catfish fillets stored at controlled freezing-point temperature (0.7±0.02)℃ for 10 and 30 d(MAP10,MAP30), MAP catfish fillets added with 5% natural preservative stored at controlled freezing-point temperature (0.7±0.02)℃ for 10, 30 and 40 d (MAPP10, MAPP30 and MAPP40). The natural preservative consists of 0.5% chitosan, 0.1% propolis, 0.075% lysozyme, 0.075% Nisin and 0.5% tea polyphenol. Microbial16S rDNA of different samples were sequenced in metagenomics analysis, bacterial composition and abundance of these groups were compared. Alpha diversity and principal component analysis were carried out to investigate the effect of the natural preservative, package and storage temperature on bacterial phase changing.【Result】Totally 25 phylum, 433 genuses of bacteria were identified in 8 sample groups. The same as CK0, the principal genus in MAP10, MAPP10, MAPP30 was Actinomyces, while it was Aeromonas (70.49%) and Pseudomonas (59.01%) in AP4 and AP7, respectively. From the respect of microbiology, MAP + controlled freezing-point temperature was better than AP + low temperature storage. During the storage, the abundance of Lactococcus increased sharply from 15.78% (MAP10) to 82.85% (MAP30), while in the MAPP group (MAPP10 and MAPP30) which supplemented with natural preservatives Lactococcus rarely could be detected. 【Conclusion】MAP + controlled freezing-point storage significantly lowered the bacterial abundance and diversity, therefore is useful to prolong the shelf life of catfish fillets. The components of tea polyphenol, Nisin and chitosan in the natural preservative used in this study markedly inhibited the growth and the multiplication of Lactococcus which is the special spoilage bacteria in the MAP fillets stored at controlled freezing point. This is important for improving the security of catfish meat against microbial contamination through precise target inhibition.  Reference | Related Articles | Metrics Cited: Baidu(1)

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Effects of Phenolic Acids on Copigmentation and Stability of Anthocyanins in Red-Fleshed Apple SU Fan, XUE Jia, YANG Xi, DENG Hong, MENG YongHong, GUO YuRong Scientia Agricultura Sinica    2017, 50 (4): 732-742.   DOI: 10.3864/j.issn.0578-1752.2017.04.013 Abstract （539）   HTML （4）    PDF （1159KB）（759）       Knowledge map    Save 【Objective】‘Zihong NO.1’ red-fleshed apple is cultivated widely in Xinjiang Autonomous Region of China. Through investigating copigmentation of phenolic acids on anthocyanins in red-fleshed apple and their stability, this paper aims at providing a theoretical basis and reference for industrial utilization of red-fleshed apple anthocyanins. 【Method】 Ultrasonic-assisted method was used to extract anthocyanins, and pH differential method was adopted to determine the total content of red-fleshed apple anthocyanins. Besides, the constituents of red-fleshed apple anthocyanins and content of monomeric anthocyanins were also analyzed by HPLC. In phosphate buffer (pH 3.0) of red-fleshed apple anthocyanins, the copigmentation effect of these four acids was evaluated. The absorption spectra and absorbance at λmax of all treatment groups as well as the contrast groups were measured before and after the treatments of heating, light exposure, oxidation and adding metal ions (Fe3+).【Result】The content of total anthocyanins in red-fleshed apple is 268.6 mg·kg-1 and mainly consist of cyanidin-3-galactoside, cyanidin-3-arabinoside and cyanidin-3-glucoside, and cyanidin-3-galactoside accounts for the largest proportion of 75.34%. The wavelength of maximum absorption of red-fleshed apple anthocyanins in water system is at 515 nm, and the color and A515mn of red-fleshed apple anthocyanins change due to different pH values. At the concentration of 0.01 mol·L-1, caffeic acid, ferulic acid, chlorogenic acid and gallic acid all showed evident copigmentation, which led to the phenomena of hyperchromic effect and the bathochromic shift in varying degrees. Especially, ferulic acid caused the greatest extent of redshift (11nm) in anthocyanins solution. After anthocyanins was heated in water-bath at 60℃, 80℃, and 100℃ for one hour, respectively, chlorogenic acid and gallic acid showed the best protection effect, which is better than caffeic acid and ferulic acid. Under the natural lighting, the half-life of anthocyanins solution without copigments was less than 7 days, while the stabilities of anthocyanins with phenolic acids as copigments increased evidently (P＜0.05). The half-life of anthocyanins with chlorogenic acid, caffeic acid, gallic acid, and ferulic acid increased by 170.87%, 142.68%, 39.56% and 23.05%, respectively. When the concentration of H2O2 in anthocyanins solution was at a range of 0.1%-0.6%, anthocyanins was oxidized rapidly, but phenolic acids can protect anthocyanins from oxidation apparently. After being oxidized by 0.1% H2O2 for one hour, the content of anthocyanins in contrast group decreased to 38.39%, however, the retention rate of treatment groups with caffeic acid, ferulic acid, chlorogenic acid and gallic acid were 57.95%, 63.10%, 59.95% and 48.81%, respectively. The solution of Fe3+ with concentration of 2.5×10-4—1×10-3 mol·L-1 had an adverse effect on anthocyanins color. In the solution containing Fe3+, the stability of anthocyanins with gallic acid as copigment was the highest. Additionally, the A515nm of treatment groups were higher than contrast group (P＜0.05). 【Conclusion】The color of red-fleshed apple anthocyanins depends on pH value of solutions obviously. The property of anthocyanins remained stable and the color kept bright red when pH＜3.0. Caffeic acid, ferulic acid, chlorogenic acid and gallic acid showed varying degrees of hyperchromic effect and the bathochromic shift on red-fleshed apple anthocyanins and evidently improved the stability of anthocyanins (P＜0.05) under various conditions of heating, light exposure, oxidation and adding metal ion of Fe3+. Reference | Related Articles | Metrics

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Drying Characteristics and Model of Bitter Melon Slice in Air-Impingement Jet Dryer XUE Shan, ZHAO WuQi, GAO GuiTian, Wu Zhong Scientia Agricultura Sinica    2017, 50 (4): 743-754.   DOI: 10.3864/j.issn.0578-1752.2017.04.014 Abstract （376）   HTML （1）    PDF （485KB）（590）       Knowledge map    Save 【Objective】In order to improve the drying quality of the bitter melon slice(BMS), shorten the drying time, the effects of the air-impingement drying conditions on the drying characteristics of the BMS were studied and the drying kinetics model was established to predict the moisture change in the drying process. 【Method】The BMS were dried by the air-impingement jet dryer made by the authors’ laboratory. The effects of different air temperatures (40, 50, 60, 70 and 80℃), air velocities (9, 10, 11, 12 and 13 m·s-1) and slice thickness (2, 3, 4, 5 and 6 mm) on the drying characteristics of materials and effective moisture diffusion coefficient of water were studied, and the activation energy was calculated. With the R2, χ2 and RMSE as the evaluation indexes, the optimum model was screened within the five commonly used dry models fitting the experimental data by Origin 8.0 software, then the relationships between the model parameters and drying conditions was establish and the prediction effect of the optimum drying model was verified.【Result】The air-impingement jet drying of BMS occurred in the falling rate drying period, and there was no constant drying rate stage. Under the experimental condition, air temperature, air velocities and slice thickness all had a certain effect on dry characteristics of BMS in air-impingement jet drying process. With the increase of air temperature and air velocities, the decrease of the slice thickness, the moisture of material decreased more fast and the drying rate was rising, the drying time was short, but the influence of air velocities was less significant than air temperature and slice thickness. The water effective diffusion coefficient of the BMS during drying process could be calculated by Fick’s second law, and it increased with the increase of air temperature, air velocities and slice thickness. The maximum effective diffusion coefficient was 2.9668×10-9 m2·s-1. Arrhenius was used to calculate the activation energy of BMS in drying process and the value of Ea was 29.89 kJ·mol-1. The five selected models all had good fitness (R2>0.98), they could predict the moisture change of the BMS in air-impingement jet drying process. Of the five models, the Two term exponential model had the highest coefficient of determination R2 (0.99937), the lowest chi-square χ2 (0.00876) and root mean square RMSE (0.000077), and it is the optimum model of the BMS in air-impingement jet drying. 【Conclusion】All the factors including the air temperature, air velocities and slice thickness had influence on the drying curve, the drying rate curve and moisture effective diffusion coefficient, and their influences were in an order of the air temperature＞air velocities＞slice thickness. Two term exponential model could properly describe the air-impingement jet drying behavior of BMS and could be used to predict the moisture change of the BMS in air-impingement jet drying process under the condition that the air temperatures between 40 and 80℃, air velocities between 9 and 13 m·s-1 and slice thickness between 2 and 6 mm. Reference | Related Articles | Metrics Cited: Baidu(1)

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Characteristics of Stable Carbon and Nitrogen Isotopic Ratios in Wheat Milling Fractions LIU HongYan, GUO BoLi, WEI Shuai, JIANG Tao, ZHANG SenShen, WEI YiMin Scientia Agricultura Sinica    2017, 50 (3): 556-563.   DOI: 10.3864/j.issn.0578-1752.2017.03.014 Abstract （336）   HTML （5）    PDF （565KB）（652）       Knowledge map    Save 【Objective】 It remains unclear for several points when identifying the geographical origin of wheat. Is there any fractionation for the stable isotopic fingerprints of milling fractions by comparing with whole wheat flour, and whether the stable isotopic fingerprints in milling fractions can be used for identifying the geographical origin of the milling fractions as well as the whole wheat flour? These problems need to be resolved. This study was conducted to reveal the characteristics and correlations of stable carbon (δ13C) and nitrogen (δ15N) isotopic ratios in different milling fractions by analyzing the difference in stable isotopic ratios among milling fractions, regions or genotypes, which could provide a theoretical and technical basis for geographical traceability of wheat and its milling fractions.【Method】 In 2014, three genotypes of wheat (Han 6172, Heng 5229 and Zhoumai 16) were grown in three regions of China which were Huixian (Henan Province), Yangling (Shaanxi Province) and Zhaoxian (Hebei Province). Three plots were conducted in each region, the typical size of plot was 10 m2, recommended local agricultural practices were adopted. Totally 27 wheat samples were collected from three regions in 2015, whole wheat flour were obtained by grinding, and flour, wheat shorts and bran were obtained by milling. δ13C and δ15N were measured for whole wheat flour and milling fractions (flour, wheat shorts and bran) by an element analysis-isotope ratio mass spectrometer. One-way analysis of variance combined with Duncan’s multiple comparison was employed to identify the significant differences among different regions, genotypes and milling fractions at isotopic levels, and Pearson correlation analysis and linear regression analysis were used to test the correlations of δ13C and δ15N among different categories of samples.【Result】Significant differences were observed among different regions in δ13C and δ15N in whole wheat flour and milling fractions, and the δ13C in wheat from three regions decreased in the following order: Huixian＞Zhaoxian＞Yangling. No significant difference was found between different genotypes in δ13C in whole wheat flour, bran and flour, and in δ15N in each category of wheat samples, significant differences were found in δ13C between wheat genotypes of Han 6172 and Heng 5229. Significant differences were also found in δ13C among different categories of wheat samples (P＜0.05), δ13C was relatively enriched in flour and depleted in wheat shorts and bran, while no significant difference was found in δ15N among different categories of wheat samples. Significant correlations were found in δ13C and δ15N between different kinds of wheat samples (P＜0.01). 【Conclusion】There were significant differences in δ13C among different wheat milling fractions, but no significant differences in δ15N among different wheat milling fractions. Significant correlations were observed between different categories of wheat samples in δ13C and δ15N. Both δ13C and δ15N of whole wheat flour and milling fractions were characterized by geographical features, which could be used for identifying the geographical origin of wheat and its milling products. Reference | Related Articles | Metrics

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Effects of pH on the Non-Covalent Forces and Structure of Myofibrillar Protein and Heat Induced Gel ZHANG Xing, YANG YuLing, MA Yun, WANG JingYu Scientia Agricultura Sinica    2017, 50 (3): 564-573.   DOI: 10.3864/j.issn.0578-1752.2017.03.015 Abstract （448）   HTML （2）    PDF （1274KB）（675）       Knowledge map    Save 【Objective】The influence of pH on non-covalent forces and structure of myofibrillar protein heat-induced gel was studied. The relationship between gel non-covalent forces and gel structure was revealed. 【Method】 AA type broilers were slaughtered. The myofibrillar proteins were extracted from breast muscle. The myofibrillar protein solution and heat-induced gel with different pH values (5.0, 5.5, 6.0, 6.5, 7.0) were prepared. The potential on myofibrillar protein gel molecule presents the electrostatic interaction was measured by zeta potential instrument. The I760/I1003 showing the hydrophobic interaction of gel, the I850/I830 showing the hydrogen bonding of gel, and the secondary structure contents were calculated by analyzing the amide I Raman spectrum region, these were measured using Raman spectrometer. The particle size distribution was measured by a particle size analyzer. The microstructure was measured using scanning electron microscope.【Result】 From pH 7.0 to 5.0, Zeta potential value of the gel changed from -17.87 to -0.263 (P＜0.05), which show that the surface negative charges and the electrostatic interaction of myofibrillar protein gel had significant decline. The normalized intensity of 760 cm-1 increased from 0.86 to 0.927, which show more Trytophan were buried and a general increase in hydrophobic interactions of myofibrillar protein gel. The normalized intensity of I850/I830 ratio decreased from 1.039 to 0.927, which indicated hydroxyl groups on the phenyl ring of tyrosine are to form hydrogen bonds with water molecules change to generate hydrogen bonds with other protein molecule residues. The interactions between myofibrillar protein molecules increased, and the interactions between myofibrillar protein and water therefore declined. From pH 7.0 to 6.5, the α-helix content of myofibrillar protein gel abruptly decreased from 59.96% to 55.24% (P＜0.05). The β-sheet content significantly increased from 15.83% to 19.44% (P＜0.05). β-turn and random coil content both significantly increased (P＜0.05). From pH 6.5 to 6.0, all structure content had no obvious change (P＞0.05). From pH 6.0 to 5.0, the α-helix content of myofibrillar protein gel significantly decreased from 51.61% to 16.76% (P＜0.05). The β-sheet content significantly increased from 22.23% to 48.93% (P＜0.05). β-turn and random coil content both significantly increased (P＜0.05). As the pH decrease, the α-helix content of myofibrillar protein gradually decreased, the β-sheet, β-turn and random coil content significantly increased (P＜0.05). From pH 7.0 to 5.0, particle size of myofibrillar protein gradually increased. D10 increased from 13.4 μm to 48.4 μm, D50 increased from 38 μm to 253 μm, D90 increased from 236 μm to 805 μm. As the pH far away from neutral condition, the microstructure of gel changed to unordered and had smaller pore. Gel has disordered microstructure in pH 5.0, when has ordered structure at pH 7.0. The largest gel pore ware found at pH 5.0, the least were found at pH 7.0. pH had a highly negative significant correlation with electrostatic interaction and hydrophobic interactions (P＜0.01), and had a positive significant correlation with hydrogen bonding and α-helix content (P＜0.05). pH also led to negative significant change of β-sheet content (P＜0.05). These show that pH had a significant impacts on electrostatic repulsion, hydrophobic interactions, intermolecular hydrogen bonding and secondary structure. Electrostatic interaction, hydrophobic interactions and hydrogen bonding had significant correlation with secondary structure (P＜0.05), which indicated non-covalent forces had significant effects on secondary structure.【Conclusion】 Non-covalent forces and secondary structure content are significantly correlated with the pH valves. The reasons of gel α-helix reduction and β-sheet increases are the decreases of electrostatic interaction, and the increase of the hydrophobic interaction and the intermolecular hydrogen bonding of myofibrillar protein gel, as the pH far away the neutral conditions. Reference | Related Articles | Metrics

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Volatile Components of Main Indica Rice Cultivars from Hunan Province SONG Wei, HU WanJun, XU ZongJi, LIU Bing, FAN Yan, NI Yang, YANG HuiPing Scientia Agricultura Sinica    2017, 50 (2): 348-361.   DOI: 10.3864/j.issn.0578-1752.2017.02.013 Abstract （459）   HTML （8）    PDF （717KB）（503）       Knowledge map    Save 【Objective】The volatile components of different indica rice varieties from Hunan province were investigated and compared to explore the possibility that using volatile compounds as indicators for characterization and differentiation of varieties, also for providing a reference for rice storage, processing and quality control.【Method】The head space-solid phase microextraction method was used to extract the volatile components from twelve varieties of indica rice and the extracted volatile substances were analyzed by gas chromatography-mass spectrometry method. The principal component analysis was adopted to analyze their flavors.【Result】A total of 265 volatile components were detected, 125 kinds of substances were screened according to the quality of not less than 80, including 56 kinds of hydrocarbons, 12 kinds of alcohols, 13 kinds of aldehydes, 14 kinds of ketones, 19 kinds of eaters, and 11 kinds of heterocylic compounds. The average percentage contribution of alkanes, olefin, aromatic hydrocarbons, alcohols, aldehydes, ketones, eaters and heterocylic compounds to the total were 26.907%, 8.417%, 7.308%, 5.810%, 9.628%, 18.626%, 13.926% and 6.819%, respectively. The coefficient of variation was 19.98%, 38.22%, 34.67%, 41.12%, 28.57%, 38.81%, 20.13% and 34.33%, respectively. High levels of 6, 10, 14-trimethyl-2-pentadecanone were detected in all species. Some varieties have unique substances, and Kauri-15-ene only existed in Zhuliangyou 819 and Zaoyou, Tezao has a special bisabolene. Isophytol, tetrahydrofurfuryl lavender alcohol and citronellol existed only in Zhuliangyou819, Tezao and Zaoyou respectively. Only Zaoxian87 contained high levels of dihydroxyacetophenone. Benzoicacid ester of silicon occurred only in Zaoyou, chloroformate n-nonyl ester was only detected in Zhongzao 39, and chloroformate n-octyl phthalate was detected only in Zhuliangyou 819 and Zaoxain 51-4. The results of principal component analysis showed that olefin, alkanes, aldehydes and heterocylic substances were the main influencing factors. The contribution rate was 35.878%, 19.267%, 18.727% and 13.596%, respectively, and the cumulative contribution rate was 87.467%. Samples (Xiangai45, Xiangzao32, Zaoxian87, Zaoxian89, Zaoxian51-4, Zhuliangyou 819, Tezao, Zhongzao39, Zaoyou) were distinguished except Zhuliangyou402, Tanliangyou83 and Zaoxian24 according to olefin. Zaoxian 87, Zaoxian89 and Zaoxian51-4 could be identified by alkanes. Zhuliangyou 819 and Zaoixan 51-4 were distinguished through aldehydes. Zaoxian 51-4 and Zaoxian 24 were identified in accordance with heterocyclic substance.【Conclusion】There are significant differences in volatile compositions and concentrations among 12 varieties of indica rice. Principal component analysis can identify specific substances and distinct paddy varieties. Reference | Related Articles | Metrics

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Effects of Different Drying Methods on the Nutrition and Physical Properties of Momordica charantia DENG YuanYuan, TANG Qin, ZHANG RuiFen, ZHANG Yan, WEI ZhenCheng, LIU Lei, MA YongXuan, ZHANG MingWei Scientia Agricultura Sinica    2017, 50 (2): 362-371.   DOI: 10.3864/j.issn.0578-1752.2017.02.014 Abstract （466）   HTML （4）    PDF （2692KB）（1111）       Knowledge map    Save 【Objective】The objective of this study is to provide a theoretical basis for choose the optimal industrial production mode of drying process of Momordica charantiaL.by studying the effect of different drying methods on nutrition, antioxidant and physical properties. 【Method】Nutrition components (polysaccharide, Vc, total phenolics, total flavonoid, carotenoid ), oxygen radical absorbance capacity (ORAC), sensory evaluation (color and hardness) and microstructure were taken as evaluation indices. Vacuum freeze drying (VFD), sun drying (SD), heat pump drying (HPD), heat air drying (HAD), microwave drying (MD) and vacuum heat drying (VHD) were adopted to dry M. charantia, and then the effects of six drying methods on texture quality and related physicochemical indices during processing were studied. 【Result】For effects of different drying methods on nutritional ingredient and antioxidant, except for VFD, M. charantia processed by other methods had the same extract ratio of polysaccharide. M. charantia dried by HPD had the highest contents of polysaccharide of 29.22 mg·g-1 DW, while MD presented the lowest contents of 16.91 mg·g-1 DW. The contents of Vc, total phenolics, flavonoid, carotenoid and ORAC of different drying methods on M. charantia were reduced after processing. M. charantia dried by HPD had the highest contents of Vc (84.81 mg·100 g-1), while MD contained the lowest (6.64 mg·100 g-1). HAD had the highest contents of total phenolic and total flavonoid (32.04 mg GAE·g-1 and 7.44 mg CE·g-1, respectively), while VFD contained the lowest (14.14 mg GAE·g-1 and 0.36 mg CE·g-1, respectively). HPD had the highest contents of carotenoid (0.86 mg·g-1 DW), while SD contained the lowest (0.11 mg·g-1 DW). The highest ORAC was obtained from HPD, MD and VHD (226.44, 224.66 and 244.10 μmol TE·g-1, respectively), while the lowest was 113.23μmol TE·g-1, which observed in VFD. As forsense and physical properties, browning degree caused by thermal processing, but VFD presented the lowest browning degree. M. charantia dried by HPD had the highest contents of chlorophyll-a and chlorophyll-b, while SD contained the lowest. SD had the highest hardness, while VFD presented the lowest. As for microstructure, HAD, HPD and SD caused more shrinkage, and MD caused damage to structure, while VFD and VHD effectively retained the myosin integrity of M. charantia slices. 【Conclusion】The results indicated that there were significant differences in nutrition and physical properties of M. charantia among different drying methods. The best nutrition and antioxidant activity were found in HPD and HAD. The bright color and good texture profile were found inVFD. M. charantia dried by SD and MD had the poor quality. Reference | Related Articles | Metrics

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The Volatile Compositions from Rice Stored with Dynamic Temperature and Humidity Based on SPME-GC/MS and  Electronic Nose (e-nose) Technics CAO Jun, LIU Xin, CHEN WenRuo, DAI BingYe, DONG Wen, CHEN YinJi Scientia Agricultura Sinica    2017, 50 (1): 142-160.   DOI: 10.3864/j.issn.0578-1752.2017.01.013 Abstract （415）   HTML （5）    PDF （3218KB）（676）       Knowledge map    Save 【Objective】 Through laboratory simulation of dynamic temperature and humidity conditions, the volatile compositions of rice were studied to find out some characteristic volatiles closely related to the rice quality. The objective of this paper is to provide reference for the construction of dynamic storage and transportation of rice. 【Method】 According to the actual transportation conditions of rice, rice was stored by simulating dynamic temperature and humidity of storage and transportation. Rice samples with 5 moisture contents (14%, 16%, 18%, 20% and 22%) were stored and transported for two months, respectively, at low temperature, middle temperature and high temperature (respectively fluctuates around 10℃, 20℃, and 30℃, humidity fluctuates around 80%). All rice samples were tested by SPME-GC/MS and electronic nose (e-nose) in this study. Principal component analysis (PCA) was used to analyze the data. 【Result】 Under different temperature conditions, the radar graphs of different moisture contents and time of rice all were different. The response values of the same moisture content rice had obvious differences under the different temperature conditions at 15 day. With the time, the differences of 14%-18% moisture contents rice samples reduced. Principal component analysis of e-nose could significantly distinguish all rice samples during storage. There were 275, 262 and 215 kinds of volatile compositions of rice samples including alkanes, olefin or alkyne, aromatic compounds, glycol ether, aldehydes, ketones, acid esters, and heterocyclic were detected, respectively, under low, medium and high temperature conditions, but only 46 kinds of which were detected in the original samples. Alkanes showed a bigger difference under low temperature conditions, and followed by medium temperature, high temperature. Olefin or alkyne, aromatic compounds, glycol ether and heterocyclic showed greater difference with temperature rising, and aldehydes, ketones, acid esters showed the largest difference under medium temperature conditions. With the time, characteristic alkane transformed from straight-chain into cycloalkane under low temperature or moisture content conditions. Haracteristic olefin or alkyne were mainly oxygen-containing or ring-shaped material at the late stage of storage. The 2,6-Di-tert-butyl-4-methylphenol, octyl phenol, and cinnamonitrile were aromatic compounds of fresh rice. With the deterioration of rice quality, methoxy or naphthalene ring materials were main characteristic aromatic compounds in rice. The 2-methyl-1-hexadecanol, benzyl alcohol, decanal, and piperitone were main characteristic glycol ether, aldehydes or ketones and had special fruity or irritating smell. Methyl-2-aminobenzoate, methyl salicylate, dihydroactinidiolide were main characteristic acid esters and had a sweet taste at early stage or under low temperature conditions, and myristic acid, decanoic acid were found at later stage and were tasteless or offensive. Furan, quinolone were characteristic heterocyclic substances with special flavor.【Conclusion】 E-nose could quickly and effectively distinguish rice samples under different moisture contents and temperatures conditions. The types and content of volatile compositions are affected by moisture content and temperature conditions of rice. Low moisture contents of rice (14%-16%) and short-term storage (30 days) are conducive to control the change of volatile compositions, and high moisture contents (20%-22%) could speed up the change of volatile compositions in rice. Reference | Related Articles | Metrics

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Electronic Nose and Electronic Tongue Combined with Fuzzy Mathematics Sensory Evaluation to Optimize Bacon Smoking Procedure WANG Qiong, XU BaoCai, YU Hai, LI Cong Scientia Agricultura Sinica    2017, 50 (1): 161-170.   DOI: 10.3864/j.issn.0578-1752.2017.01.014 Abstract （414）   HTML （8）    PDF （408KB）（1152）       Knowledge map    Save 【Objective】Using Electronic Nose (E-nose), Electronic tongue (E-tongue) and Fuzzy Mathematics Sensory Evaluation to pick out a bacon smoked by a certain brand and concentration of smoking liquid which resembles the traditional wood chips smoking bacon in flavor, and study the feasibility and accuracy of optimizing the bacon smoking procedure with E-nose and E-tongue. 【Method】Bacons made with three brands and three concentrations of smoking liquid and traditional wood chips smoking were analyzed by E-nose and E-tongue and verified with fuzzy mathematics sensory evaluation.【Result】After analyzing the E-nose Principle Component Analysis (PCA) chart, the accumulating contribution of Principle Components (PC) 1 and 2 is 99.760%, much larger than 85%, which means PC1 and PC2 have contained enough information to reflect the whole sample information. The distribution areas of sample 4 (3‰ Minghua MH-SO152) and sample 1 (woodchips smoked) are obviously separated, which suggests that the odor of the two samples are clearly different. However, the distribution areas of sample 5 (1‰ Minghua SY-SO968), sample 7 (3‰ Minghua SY-SO968), sample 9 (2‰ Jinniushan Ⅱ), and sample 10 (3‰ Jinniushan Ⅱ) are close to that of sample 1, which means their smell is close to sample 1 as well. The distribution areas of sample 6 (2‰ Minghua SY-SO968) and sample 1 overlap partially, which means the smell of sample 6 (2‰ Minghua SY-SO968) and sample 1 (wood chips smoked) are basically the same, thus the bacon added with 2‰ Guangzhou Minghua SY-SO968 smoking liquid smells basically the same as the traditional one. By analyzing the E-tongue Principle Component Analysis (PCA) chart, the accumulating contribution of Principle Components 1 and 2 is 88.903%, larger than 85%, enough to reflect the general sample information. The distribution areas of sample 2 (1‰ Minghua MH-SO152), sample 3 (2‰ Minghua MH-SO152) and sample 4 (3‰ Minghua MH-SO152) are far away from sample 1, which shows that their taste can be effectively distinguished from woodchips smoked sample 1. And the distribution areas of sample 8 (1‰ JinniushanⅡ), sample 9 (2‰ Jinniushan Ⅱ) and sample 10 (3‰ Jinniushan Ⅱ) locate near sample 1, thus they taste relatively like sample 1. The distribution areas of samples 5 (1‰ Minghua SY-SO968), 6, and 7 (3‰ Minghua SY-SO968) are closest to sample 1, which means they taste closest to sample 1, thus the bacons added with Guangzhou Minghua SY-SO968 smoking liquid taste closest to the traditional one. In Fuzzy Mathematic Sensory Evaluation and flavor description, the comprehensive scores of samples 1, 6, 7 and 10 (3‰ Jinniushan Ⅱ) are close and higher than sample 8, and described as heavy smoking flavor and good taste. The Fuzzy Mathematic Sensory Evaluation score of sample 6 is closest to sample 1, and the difference is merely 0.05, which verifies the E-nose and E-tongue results.【Conclusion】After analyzing the E-nose and E-tongue Principle Component Analysis charts, the bacon added with 2‰ Guangzhou Minghua SY-SO968 smoking liquid smells basically the same as the traditional one, and tastes closest as well, which means it can be used to replace the traditional smoking technique. Fussy mathematics sensory evaluation scores verified the fact and proved E-nose and E-tongue can be used to optimize bacon smoking procedure efficiently, thus provides a reference method to optimize meat production technique from flavor perspective.  Reference | Related Articles | Metrics

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Properties of the Extruded Products of Cereal Grains Compounded with Cordyceps militaris HU Qiu-hui, ZHONG Lei, YANG Wen-jian, PEI Fei, FANG Yong, MA Ning, TANG Xiao-zhi, ZHAO Li-yan, YANG Fang-mei Scientia Agricultura Sinica    2016, 49 (24): 4772-4784.   DOI: 10.3864/j.issn.0578-1752.2016.24.009 Abstract （352）   HTML （1）    PDF （754KB）（559）       Knowledge map    Save 【Objective】 Formulation of pre-blended powder from five cereal grains by adding Cordyceps militaris was performed by the twin-screw extrusion. The impact of addition of C. militaris on the characteristicsofextruded products was explored. The result of this study will provide technical supports for development of the nutritious and novel functional cereal products from cereal grains and edible fungi. 【Method】 The mixed ratio of five cereal grains was optimized by linear programming. The characteristic features of the extruded products from cereal grains compounded with C. militaris and non- supplemented cereal grains were assessed in terms of protein, fat, minerals , dietary fiber, hardness, colour difference, and amino acids content. The differences of volatile compounds between non-supplemented and supplemented cereal products were also detected by electronic-nose in macro respect and then analyzed by GC-MS. 【Result】 The mixed ratio for C. militaris and cereal grains was 1:10 by weight. The ratio of cereal grains including rice, adlay, red beans, glutinous rice, soybeans was 12﹕1﹕2﹕2﹕3. Addition of Cordyceps militaris could significantly reduceenergy, carbohydrate content, the degree of fracturability and L* value of the puffed products of cereal grains (P＜0.05), while other values such as springiness, adhesiveness and chewiness had no significant difference. Total essential amino acid content, a*, b*, △E, protein, ash, potassium, calcium, sodium and other minerals of extruded products from cereal grains compounded with C. militaris were markedly increased compared with that of extruded products from cereal grains, while the ratios between total essential amino acid content and total amino acid content, between total essential amino acid content and non total amino acid content, SRC, index of essential amino acid were 40%, 60%, 54%, and 1.08, and they met the requirements of FAO/WHO standard schemas, which indicated that C. militaris was not only able to affect organoleptic properties but also could improve the nutrition features for the final extruded products. Aroma characteristics of the extruded products supplemented with C. militaris or without could obviously distinguished by electronic-nose. GC-MS results revealed that there were 27 and 31 volatile compounds in the extruded products before and after adding C. militaris, andthe specific volatile components in the extruded product with C. militaris included esters, carbazoles, ethers, alkynes, pyrroles and paroxetine. The specific volatile components were mainly propyl isocyanate, 1,2:7,8-dibenzocarbazole, 2(2-Ethoxyethoxy)ethano, 5-methyl-1-hexynyl and N- methylpyrrole. The great contribution to volatile flavors was accounted for 2-pentylfuran, 3-octen-2-one, dodecane and tridecane of total flavor compounds, respectively. 【Conclusion】 C. militaris. added into the extruded products has a profound impact on the characteristic features such as texture, nutrition and flavors. The new composite products using cereal grains as the carrier will add values to traditional extruded products in amino acids content, taste, health protection. Reference | Related Articles | Metrics

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Effect of Modified Atmosphere Packaging on Postharvest Physiology and Quality of ‘Korla Xiangli’ Pears During Storage JIA Xiao-hui, WANG Wen-hui, TONG Wei, DU Yan-min, WANG Zhi-hua, JIANG Xiu-cheng Scientia Agricultura Sinica    2016, 49 (24): 4785-4796.   DOI: 10.3864/j.issn.0578-1752.2016.24.010 Abstract （462）   HTML （3）    PDF （1979KB）（655）       Knowledge map    Save 【Objective】 The objective of this study is to optimize packaging bags and provide a scientific foundation for exploring a simple and efficient new preservation technology of ‘Korla Xiangli’ pears during storage by studying the effect of modified atmosphere packaging on postharvest physiology and quality. 【Method】 Storage experiments were performed with commercially mature ‘Korla Xiangli’ pears using four packaging bags, including 0.02 mm thickness PE film bags, 0.04 mm thickness PE film bags, 0.05 mm thickness PE film bags and 0.04 mm thickness PVC film bags. The bags were sealed after the fruits were put into the bags. Theses fruits were stored under the conditions of temperature at (0±0.3)℃ and relative humidity at (RH) 90%-95%. The fruits of unsealed treatment were used as the control. The concentrations of O2, CO2 and ethylene in different packaging bags were monitored regularly. In business sales peak of ‘Korla Xiangli’ pears (refrigerated 180 d and 240 d), the changes of L and h values and chlorophyll fluorescence parameters of peel, relative electrical conductivity, malondialdehyde, ethanol, aldehyde, fruit firmness, total soluble solids, titratable acid, ascorbic acid and other physical and chemical indicators were determined, and the weight loss ratio, stalk preservation index, core browning index and sensory scores in different periods of storage were calculated. 【Result】The concentrations of O2 and CO2 in sealed bags reached equilibrium on the 30th day. The ability level of gas adjustment was 0.05 mm thickness PE film bags, 0.04 mm thickness PE film bags, 0.04 mm thickness PVC film bags and 0.02 mm thickness PE film bags from high to low in turn. The 0.04 mm thickness PVC film bags and 0.04 mm thickness PE film bags were optimum modified atmosphere packaging bags for ‘Korla Xiangli’ pears by two years tests. The results of indicators showed that the adopted packaging bags reduced weight loss ratio, slowed down the rise of L value of peel, relative electrical conductivity, malondialdehyde, ethanol, aldehyde, and core browning index, restrained h value, Fm and Fv and Fv/Fm of peel, improved stalk preservation index, fruit firmness, total soluble solids, titratable acid and ascorbic acid had a good effect of maintaining quality. On the 180 d, the L value, h value were significantly different between treatment and control groups (P＜0.05), and the stalk preservation index, core browning index and weight loss ratio were not significantly different (P>0.05), but in the late storage (240 d), the above indexes were significantly different between treatment and control groups (P＜0.05). The 0.04 mm thickness PE film bags and 0.04 mm thickness PVC film bags maintained sensory score of ‘Korla Xiangli’ pears, but the sensory scores of 0.05 mm thickness PE film bags were lowered significantly, and core browning was increased. 【Conclusion】‘Korla Xiangli’ pears more embodied in the storage period by using 0.04 mm thickness PE film bags and 0.04 mm thickness PVC film bags for modified atmosphere packaging, and the O2 and CO2 concentrations in bags played a main role, and when maintained O2 at 14.5% to 17.0% and CO2 at 2.5% to 3.0% had a good preservation effect. Ethylene concentration showed less effect on the preservation of ‘Korla Xiangli’ pear. Reference | Related Articles | Metrics

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Effect of Extrusion on Digestion Properties and Volatile Compounds in Germinated Brown Rice Compounded of Flammulina velutipes Flour FANG Yong, WANG Hong-pan, PEI Fei, MA Ning, TANG Xiao-zhi, YANG Wen-jian, HU Qiu-hui Scientia Agricultura Sinica    2016, 49 (23): 4606-4618.   DOI: 10.3864/j.issn.0578-1752.2016.23.013 Abstract （427）   HTML （1）    PDF （4413KB）（591）       Knowledge map    Save 【Objective】The objective of this study was to investigate the effect of extrusion process on digestion properties and volatile compounds in germinated brown rice compounded of Flammulina velutipes flour through the changes of starch, protein and volatile compounds, thus providing references for the analysis of extrudant digestion properties and flavor.【Method】 In order to study the effects of extrusion on digestion properties and flavor compounds, germinated brown rice compounded of Flammulina velutipes was extruded to investigate the particle microstructure of starch and protein, the protein molecular weight and protein secondary structure, the digestibility of starch and protein, and the volatile compounds using scanning electron microscope, SDS-PAGE electrophoresis, infrared spectroscopy, in vitro digestion method and gas chromatography-mass spectrography.【Result】The results showed that the granule shapes of extruded starch and protein were changed into irregular shape compared with the un-extruded compounded powder. Moreover, the starch content and protein content in germinated brown rice compounded of F. velutipes extrudant decreased by 8.26% and 1.00%, respectively. However, the reduced sugar content, the soluble sugar content, in vitro starch digestibility and in vitro protein digestibility increased by 1.35 times, 18.45%, 30.68% and 25.57%, respectively. The protein molecular weight mainly distributed in 50, 36, 33, 22, 19 and 13 kD in un-extruded compounded powder. However, the 50 kD molecular weight disappeared and the 36 kD molecular weight had no change in germinated brown rice compounded of F. velutipes extrudant. The infrared spectra of protein in extruded were similar to that of un-extruded powder, but the absorption peak intensity had significant difference between 1 645 and 1 544 cm-1. The contents of aldehydes, alcohols, pyrazines and ketones compounds in germinated brown rice compounded of F. velutipes extrudant were increased by 18.93%, 44.17%, 77.64% and 1.56 times, respectively. The aldehydes and alcohols compounds in extruded products of germinated brown rice showed a decline trend compared with un-extruded germinated brown rice. However, the increasing trend to that of the extruded products of germinated brown rice compounded of F. velutipes was exhibited, indicating the flavor enhancement of F. velutipes.【Conclusion】Extrusion technology could improve the digestion characteristics of germinated brown rice compounded of F. velutipes extrudant. Meanwhile, the mixture of F. velutipes could enhance the flavor of the product. Reference | Related Articles | Metrics

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Multiplex Enrichment Quantitative PCR Assays for the Detection of Vibrio alginolyticus, Vibrio parahaemolyticus, Vibrio vulnificus and Vibrio cholerae WEI Shuang, WANG Tian-jie, LONG Yang, ZHOU Guang-biao, LIN Chun-gui, HUANG Shuai, WU Xi-yang Scientia Agricultura Sinica    2016, 49 (23): 4619-4627.   DOI: 10.3864/j.issn.0578-1752.2016.23.014 Abstract （520）   HTML （2）    PDF （1388KB）（363）       Knowledge map    Save 【Objective】Vibrio parahaemolyticus, V. alginolyticus, V. cholerae and V. vulnificus have been recognized as the important foodborne pathogens causing human disease. It is important to establish a detection method to identify these 4 foodborne pathogenic Vibrio species in order to ensure food safety. To develop a multiplex enrichment quantitative PCR (ME-qPCR) assay that can simultaneously detect Vibrio parahaemolyticus, V. alginolyticus, V. cholerae and V. vulnificus in the presence of an internal amplification control (IAC), to make it possible for researchers and technical staff achieve simple detection of these 4 foodborne pathogens. 【Method】 Inner and outer species-specific PCR primers were designed based on gyrB gene for V. alginolyticus, collagenase gene for V. parahaemolyticus, vvhA gene for V. vulnificus and ompW gene for V. cholerae, 16S rRNA gene of bacteria as IAC primers was used to indicate false-negative results. All inner and outer primers were used in first round multiplex enrichment PCR with a small number of cycles so as to avoid competition between amplicons. Each gene has 4 types of probable products which can be the templates for the next nested real-time PCR. This can enrich the target genes from the genomic DNA template successfully. The reaction product was then diluted and analyzed individual real-time PCRs using inner primers. The results were analysed by amplification curve and melting curve. ME-qPCR method was developed after optimization of the first round multiplex enrichment PCR cycle numbers (10, 15 and 20 cycles). The specificity of ME-qPCR was validated by 14 bacteria standard strains. The sensitivity and quantitative capability of ME-qPCR were tested by using 10-fold serially diluted genomic DNA of 4 Vibrio strains. Strains as templates, and then, the ME-qPCR was used to detect 69 suspicious Vibrio strains and the results were compared with physiological and biochemical experiments. 【Result】 Fifteen cycles were determined to use in first round multiplex enrichment PCR in this study finally. The results showed that the ME-qPCR assay was rapid, high-throughput, sensitive and specificand the existence of IAC could successfully eliminate false-negative results. The sensitivity of ME-qPCR was 0.001ng per reaction, about 10 times higher than real-time PCR. The ME-qPCR was validated with 69 suspicious Vibrio strains. The result showed that 27 green bacteria colonies were V. parahaemolyticus, 22 yellow bacteria colonies were V. alginolyticus, 1 yellow bacteria colony was V. vulnificus, and V. cholerae was not detected. The results are consistent with physiological and biochemical experiments. 【Conclusion】 The ME-qPCR assay is specific, stable and reliable for the detection of V. parahaemolyticus, V. alginolyticus, V. cholerae and V. vulnificus. It’s sensitivity is high, and can effectively indicate the false negative of PCR reaction, the results without gel electrophoresis, and is suitable for the rapid screening of 4 common pathogenic vibrio. in food Reference | Related Articles | Metrics

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Effects of Controlled Freezing Point Storage on the Protein Phosphorylation Level ZHANG Yan, LI Xin, LI Zheng, LI Meng, LIU Yong-feng, ZHANG De-quan Scientia Agricultura Sinica    2016, 49 (22): 4429-4440.   DOI: 10.3864/j.issn.0578-1752.2016.22.015 Abstract （436）   HTML （1）    PDF （2001KB）（784）       Knowledge map    Save 【Objective】 The aim of this study was to investigate the effect of controlled freezing point on protein phosphorylation level, so as to provide a new theoretical basis for controlling meat quality by controlled freezing point. 【Method】 The longissimus doris (LD) of large tail×small tail crossed sheep were obtained and divided into two groups: refrigeration group and controlled freezing point group. Each LD was assigned to 6 storage times (0.5 h, 12 h, 24 h, 3 d, 5 d and 9 d). Kit for protein kinase activity measurement and enzyme linked immunosorbent assay were applied to detect protein kinase activity. A gel-based phosphoproteomic study was performed. And SDS-PAGE electrophoresis and fluorescence staining were applied to gain the protein bands of sarcoplasmic proteins and myofibrillar proteins stained by SYPRO Ruby and Pro-Q Diamond. A software named Quantity One was used to analyze the protein phosphorylation level by measuring the fluorescence intensity.【Result】 At 12 h, the protein kinase activity of controlled freezing point group significantly increased (P＜0.05) and that of refrigeration group significantly decreased. The protein kinase activity of the two groups were reduced from 12h to 9 d, which was significantly higher in controlled freezing group compared with refrigeration group (P＜0.05). Seventeen protein bands distributed from 15-250 kDa in each sarcoplasmic protein sample were analyzed and the results suggested that storage temperature influenced (P<0.001) the protein phosphorylation level of all sarcoplasmic proteins significantly. The total phosphorylation level of sarcoplasmic proteins in refrigeration group increased at first and then decreased while the sarcoplasmic proteins in controlled freezing point group showed an opposite variation trend. The phosphorylation level of 3 d was the highest, while the lowest was 24 h. Globally, the sarcoplasmic proteins of refrigeration group had the higher total phosphorylation level than controlled freezing point group during 12 h to 3 d. However, the total phosphorylation level of the sarcoplasmic proteins of controlled freezing point was higher than refrigeration group on 9 d. Twenty protein bands distributed from 15-250 kDa in each myofibrillar protein sample were analyzed and the results suggested storage temperature influenced the protein phosphorylation level of all myofibrillar proteins very significantly (P<0.001). The total phosphorylation level of myofibrillar proteins increased firstly and then decreased in two groups. And the highest phosphorylation level of 24 h in refrigeration group and 12 h in controlled freezing point group was the highest. Total phosphorylation level of myofibrillar protein had no significant difference between two groups from 0.5 h to 12 h. However, total phosphorylation level of myofibrillar protein was higher in refrigeration group compared with controlled freezing group from 24 h to the end of storage.【Conclusion】 The controlled freezing point storage regulated the phosphorylation level of protein by affecting the activity of protein kinase, which can indirectly regulate the meat quality by influencing the glycometabolism, muscle contraction and degradation of skeleton protein. Reference | Related Articles | Metrics

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Separation and Antioxidant Activity of Different Phenolic Compound Fractions from Litchi Pulp DONG Li-hong, ZHANG Rui-fen, XIAO Juan, DENG Yuan-yuan, ZHANG Yan, LIU Lei, HUANG Fei, WEI Zhen-cheng, ZHANG Ming-wei Scientia Agricultura Sinica    2016, 49 (20): 4004-4015.   DOI: 10.3864/j.issn.0578-1752.2016.20.014 Abstract （455）   HTML （3）    PDF （501KB）（655）       Knowledge map    Save 【Objective】The total phenolics, total flavoniods and tannin content and antioxidant activity of different phenolic compound fractions from litchi pulp were compared to clarify the effective phenolic compounds of antioxidant activity from litchi pulp. The results of research will provide a basis for revealing the main compounds from litchi pulp to human health.【Method】Litchi pulp polyphenol extracts were divided into four phenolic compound fractions (F1, F2, F3 and F4) by C18 silica gel column. Then the total phenolics, total flavonoids and tannin content and the compositions of free phenol of four compound fractions were determined. Also, the FRAP, DPPH, ORAC and CAA antioxidation indexes were adopted to evaluate the antioxidant capacities of four different compound fractions.【Result】The results showed that litchi pulp polyphenol extracts were well-divided into four phenolic compound fractions. Among them, the yield of F2 was as high as 36%, and others’ were 18.71%, 16.79% and 21.12%, respectively. Total phenolics, total flavonoids and tannin content of four phenolic compound fractions ranged from 218.86 to 499.78 mg GAE/g DW, 414.94 to 1 285.45 mg RE·g-1 DW and 83.35 to 483.43 mg CE·g-1 DW, respectively. Among the four compound fractions tested, F2 exhibited the highest total phenolics, total flavonoids and tannin content with their corresponding percentage contribution as high as 50.31%, 54.24% and 72.06% to litchi pulp polyphenol extracts, followed by F3, F4, and finally F1. Procyanidin B2 and epicatechin in F2, quercetin-3-O-rutinoside-7-O-α-L-rhamnoside in F3 and rutin in F4 were identified by HPLC. The results of antioxidation indexes showed that FRAP values of four compound fractions were F2＞F3＞F4＞F1. The IC50 values of DPPH free radical scavenging were 27.00, 9.76, 19.41 and 16.25 μg·mL-1, respectively, then F2 exhibited the strongest DPPH free radical scavenging ability with minimum IC50 value among the four compound fractions, followed by F4, F3, and finally F1. Also, the ORAC values of them were F2＞F3＞F4＞F1 and the CAA values were F2＞F3＞F4, F1. Among them, F2 exhibited the highest ORAC and CAA values as 8.36 mmol TE·g-1 DW and 190.71 μmol QE·g-1 DW with the percentage contribution as high as 50.42% and 84.91% to total ORAC and CAA values of litchi pulp polyphenol extracts, respectively.【Conclusion】These results indicated that there were significant differences in total phenolics, total flavonoids and tannin content and antioxidant activity among the four phenolic compounds fractions from litchi pulp. The compositions of each phenolic compound fraction were also different. What’s more, F2 exhibited the highest yield, total phenolics, total flavonoids and tannin content with the best antioxidant capacities. Interestingly, the phenolics in F2 may be the most main active compounds of antioxidant activity from litchi pulp. Reference | Related Articles | Metrics Cited: Baidu(1)

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The Sensory Evaluation Methods of Production Process and Product of Lanzhou Hand-Extended Noodles WEI Yi-min, XING Ya-nan, ZHANG Ying-quan, KONG Yan, LI Ming, ZHANG Bo, TANG Na Scientia Agricultura Sinica    2016, 49 (20): 4016-4029.   DOI: 10.3864/j.issn.0578-1752.2016.20.015 Abstract （562）   HTML （3）    PDF （335KB）（954）       Knowledge map    Save 【Objective】 Experiment, verification and statistical analysis were combined in this study to establish a set of scientific and rational sensory evaluation attributes for Lanzhou hand-extended noodles (LZHEN), in order to provide methods for noodle quality evaluation, developing specific flour, and breeding special wheat varieties, also providing reference or case for the establishment of the traditional food sensory evaluation methods. 【Method】 Eight kinds of commercial wheat flours and two kinds of wheat flours with large differences in the quality premixed in a certain ratio were used as raw materials to make noodles by professional masters in laboratory. Using a preliminary method, masters evaluated the process procedure and panelists evaluated the cooked noodles. Then analyze, improve, and test the accuracy and precision of sensory evaluation methods on process procedure and the cooked noodles of LZHEN. 【Result】 The experiments of eight kinds of wheat flours processed by one master and six kinds of premixed wheat flours processed by three masters were made in triplicate. The results showed that the sensory evaluation methods established in this study had less significant difference in different evaluation times, fitting line, high accuracy, which means that the methods could be used to evaluate LZHEN. 【Conclusion】 By design, implementation and verification, the main quality attributes finalized for the process procedure and cooked noodles quality of LZHEN were as follow: 1) degree of mixing and hardness of dough, fracture and homogeneity of strips, slitting effort by hand and stickiness, dough color after resting and extending force were decided to assess the processing procedure quality attributes. 2) color, surface appearance, hardness, stickiness, elasticity, smoothness and flavor were decided to assess the cooked noodles quality attributes. Reference | Related Articles | Metrics

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Separation and Purification of Polyphenols in Rice Bran by Macroporous Resins TONG Xin, ZHANG Rui-fen, DENG Yuan-yuan, XIAO Juan, LIU Lei, ZHANG Yan, WEI Zhen-cheng, ZHANG Ming-wei Scientia Agricultura Sinica    2016, 49 (19): 3818-3830.   DOI: 10.3864/j.issn.0578-1752.2016.19.013 Abstract （434）   HTML （2）    PDF （712KB）（544）       Knowledge map    Save 【Objective】The objective of this study is to screen a resin with a good adsorption and desorption performance to rice bran polyphenols (RBP) and optimize the purification technique, to compare the total phenols, total flavonoids content and antioxidant activity before and after purification, thus providing a theoretical basis for the deep processing and utilization of rice bran.【Method】The behavior of static adsorption and desorption, dynamic adsorption and desorption of 9 macroporous resins (HPD-100, HPD-200A, HPD-300, HPD-700, D101, HPD-722, AB-8, ADS17, and HPD-826) with different polarities to RBP was determined. Kinetic characteristics of static adsorption of the preferred resin were analyzed. The purification technique of macroporous resin to RBP was developed through the dynamic adsorption and desorption curves under different loading and elution conditions, including phenolic concentrations in loading samples, sampling rates, sampling volumes and ethanol concentrations in eluent. The phenolic profiles in RBP before and after resin purification were analyzed by HPLC analysis. Their total phenolic and flavonoid contents, oxygen radical absorption capacity (ORAC) and cellular antioxidant activity (CAA) were also estimated. 【Result】HPD-300 exhibited the best capability of adsorption and desorption to RBP among the 9 selected macroporous resins. The saturated absorption quantity of HPD-300 resin to RBP was 9.04 mg GAE·g-1, and the desorption rate was 82.62%. It took 6 h for HPD-300 resin to reach absorption equilibrium. The optimized purification parameters were as follows: the phenolic concentration of loading sample is 1 mg GAE·mL-1, sampling rate is 3.0 BV·h-1, sampling volume is 3.5 BV, eluent is 70% ethanol, flow velocity is 3.0 B V·h-1. After HPD-300 resin purification, the total phenolic content increased by 2.6 times from 88.07 µg GAE·mg-1 to 320.72 µg GAE·mg-1, and the total flavonoids content increased by 3.4 times from 30.04 µg CE·mg-1 to 133.67 µg CE·mg-1. Ten phenolic compounds were identified from rice bran phenolic extract, which were gallic acid, protocatechuic acid, vanillic acid, p-hydroxy benzoic acid, caffeic acid, clove acid, epicatechin, catechins, vanillic aldehyde, p-coumaric acid and ferulic acid by HPLC analysis. The phenolic profiles of the extract were not changed after HPD-300 resin purification, but the concentrations of 10 phenolic compounds increased by 0.4-2.4 times. The ORAC and CAA antioxidant activity of the extract changed from 1 327.51 µmol TE·g-1 and 29.19 µmol QE·g-1 before purification to 3 248.21 µmol TE·g-1 and 95.24 µmol QE·g-1 after purification, and increased by 1.4 and 2.2 times, respectively.【Conclusion】The total phenolic and flavonoid contents and antioxidant activity increased by 1-3 times after HPD-300 resin purification. The individual phenolic compounds in the extract were not lost significantly during purification. Therefore, HPD-300 macroporous resin was suitable to purify rice bran phenolic extract. Reference | Related Articles | Metrics

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Effect of Fermentation on the Polysaccharides Processing Characteristics in Apple Pomace JIA Feng,GUO Yu-rong, LIU Dong, YANG Xi, DENG Hong, MENG Yong-hong Scientia Agricultura Sinica    2016, 49 (19): 3831-3844.   DOI: 10.3864/j.issn.0578-1752.2016.19.014 Abstract （508）   HTML （5）    PDF （1192KB）（563）       Knowledge map    Save 【Objective】The output of apple in China accounts for over 50% of the world annually. Among those apples, there are about 20% of apple fruits are used as raw materials to produce deep-processed products. As a result, apple pomace of thousands of tons are produced each year, which has caused the tremendous waste of apple recourse because these pomace are generally sold as a cheap fertilizer or are discarded directly as junks. The difference of physical and rheological property, viscosity-average molecular weight, and basic structure of polysaccharides between raw pomace and fermented apple pomace was studied in order to provide innovative thoughts and a theoretical basis for the exploitation of apple polysaccharides.【Method】Apple pomace (AP), wine fermented apple pomace polysaccharides (WFP), vinegar fermented apple pomace polysaccharides (VFP) were used as experimental materials, the paper investigated overall the processing properties of polysaccharides in fermented apple pomace through comparing with the extract ratio, solubility, hygroscopicity, moisture retention, and emulsifiability, foaming capacity and stability among AP, WFP and VFP. Besides, the rheological properties, microstructure, viscosity-average molecular weight were determined by using rheometer, desktop scanning electron microscope (DSEM), ubbelohde viscometer, respectively.【Result】The extraction ratio of AP was 5.68%, while that of polysaccharide in fermented apple pomace was 6%-7%, both of which had a significant difference (P＜0.05). The solubility of VFP and WFP were, respectively, 0.1405 g·mL-1 and 0.0771 g·mL-1, and significantly higher (P＜0.05) than AP (0.0283 g·mL-1). Compared to AP, the stability of foaming, hygroscopicity, moistureretention of polysaccharides, fermented apple pomace were significantly increased (P＜0.05), while oil absorption, emulsifiability and its stability obviously decreased (P＜0.05). According to analysis on rheological property, AP, WFP, VFP could be attributed to typical non-Newtonian fluid, and the apparent viscosity showed obvious dependent-characteristic of concentration. Besides, VFP and WFP had great resistance against temperature change. The findings of analysis of viscosity-average molecular weight and DESM indicated that the viscosity-average molecular weight of AP, WFP, VFP all distributed in the range of 15-130 kDa, and AP＞WFP＞VFP. Additionally, the microstructure analysis showed that AP consisted of band, bar and flake, twining with each other and forming firm network. WFP contained dentation, bar and flake, so its cross-linking was comparatively lower. But VFP mainly consisted of flake, overlapping with one another, and cross-linking was the lowest.【Conclusion】WFP, VFP were greatly improved in physicaland rheological properties, microstructure and viscosity-average molecular weight, indicating the processing property of polysaccharides in fermented apple pomace was superior to AP. Reference | Related Articles | Metrics Cited: Baidu(1)

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Thermal Transition Properties of Soybean Protein Isolate-Corn Starch-Wheat Gluten Mixtures SU Xiao-fang, LI Shu-jing, ZHANG Bo, ZHANG Jin-chuang, ZHANG Wei Scientia Agricultura Sinica    2016, 49 (18): 3618-3627.   DOI: 10.3864/j.issn.0578-1752.2016.18.016 Abstract （436）   HTML （2）    PDF （801KB）（665）       Knowledge map    Save 【Objective】 Thermal transition properties of protein-starch mixtures, which are not fully understood, are important for the food processing, such as optimizing the thermal treatment parameters, controlling final product quality and even saving the processing energy.【Method】 Soybean protein isolate (SPI), corn starch (CS) and wheat gluten (WG) were selected as raw materials. The mixtures of SPI-CS, SPI- WG, WG-CS, SPI-CS-WG were blended at the range of 0-100%. Their thermal transition properties were determined using differential scanning calorimetry (DSC),with water content of 50% and heating rate of 10℃·min-1 over 20 to 130℃.【Result】 With an increase at the water content from 30 to 70%, onset temperature (To) and peak temperature (Tp) of SPI 11 S subunits decreased from 105℃ to 95℃ and from 114℃to 99℃, respectively, meanwhile, thermal transition enthalpy (△H)of 11 S subunit increased from 2.8 to 6.2 J·g-1.△H of CS increased from 3.6 to 14.1 J·g-1. No thermal transition was observed in WG at 20 to 130℃. It was probably due to the high moisture increasing the molecular mobility of protein or starch. When the moisture was 50%, compared with 100% ingredient, △H of 11 S subunit in SPI-CS mixtures significantly decreased by about 1.41 J·g-1 in average, meanwhile, To and Tp of CS remarkably increased by about 14℃ and 13℃, respectively. Only thermal transition of SPI was observed in SPI-WG mixtures. To and △H of 11 S subunit decreased by 2.40 J·g-1 in SPI-WG mixtures compared with those of 100% SPI. Similarly, only thermal transition of CS was observed in CS-WG mixtures. In WG-CS mixtures, Tp of CS dramatically increased by about 12℃ compared with 100% CS. In SPI-CS-WG mixtures, when CS:WG was 1﹕1, To, Tp and △H of 11 S subunit obviously decreased by about 4℃, 5℃ and 1.64 J·g-1, respectively, compared with 100 % SPI. Competition between protein and starch for absorbing water was probably the reason for the increasing of thermal transition temperature of CS, and steric hindrance of WG or CS may be the reason for the decreasing thermal transition enthalpy of 11 S subunit.【Conclusion】Addition of wheat gluten or corn starch could decrease thermal transition enthalpy of soybean protein and addition soybean protein isolate or wheat gluten could increase thermal transition temperature of corn starch. Reference | Related Articles | Metrics

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Effects of High Oxygen Modified Atmosphere Packaging on Protein Oxidation, Calpain Activity and Protein Proteolysis of Pork During Postmortem Refrigerated Storage CHEN Lin, ZHOU Guang-hong, XU Xing-lian, ZHANG Wan-gang Scientia Agricultura Sinica    2016, 49 (18): 3628-3638.   DOI: 10.3864/j.issn.0578-1752.2016.18.017 Abstract （427）   HTML （4）    PDF （3084KB）（839）       Knowledge map    Save 【Objective】 The objective of this study was to investigate the effect of high oxygen modified atmosphere packaging (HiOx, 80% O2/20% CO2）on protein oxidation, calpain activity and protein proteolysis of pork during refrigerated storage. This could help explaining the mechanism of regulation behind HiOx in pork quality. 【Method】 Twelve longissimus dorsimuscles of Duroc × Landrace × Yorkshire crossbred pork were precooled at 4℃ for 24 h, and then randomly assigned to either HiOx or vacuum packaging (VP) and stored for 1, 4 and 6 d at 4℃. The carbonyl content and distribution, sulfhydryl content, sarcomere changes, calpain activity, titin and troponin-T degradation were determined, respectively. 【Result】 Carbonyl content of samples from HiOx was significantly higher than the samples from VP at 4 and 6 d of storage (P＜0.05). HiOx samples showed fluorescence signal in the peripheral area of cell membrane and then the fluorescence signal spread to the internal cellular environment at 1 and 4 d of postmortem refrigerated storage. At 6 d of postmortem refrigerated storage, samples under HiOx presented a strong fluorescence light, with a glaring fluorescence intensity more pronounced in a peripheral area corresponding to the cell membrane and to a region in close contact with the cell membrane, while VP samples presented weaker fluorescence signal. Sulfhydryl content of HiOx samples was significantly lower compared with VP samples at 6 d of postmortem storage (P＜0.05). Samples from VP showed weakening M line, blurry A band as well as broken Z line during postmortem refrigerated storage, whereas samples under HiOx remained less affected. μ-Calpain activity was less in samples from HiOx compared with that from VP at 1 d of storage (P＜0.05). Titin and troponin-T showed less proteolysis in samples from HiOx than that from VP at 4 and 6 d of postmortem refrigerated storage (P＜0.05). 【Conclusion】 Increased protein oxidation under HiOx could inhibit μ-calpain activity and protein proteolysis of pork during postmortem refrigerated storage. Reference | Related Articles | Metrics Cited: Baidu(7)

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Analysis and Comparison of Calpain in Mutton with Different Levels of Tenderness DU Man-ting, LI Xin, LI Zheng, GAO Xing, ZHANG Cai-xia, ZHANG De-quan Scientia Agricultura Sinica    2016, 49 (17): 3425-3432.   DOI: 10.3864/j.issn.0578-1752.2016.17.015 Abstract （347）   HTML （2）    PDF （599KB）（371）       Knowledge map    Save 【Objective】Calpain plays an important role in postmortem tenderization through the proteolysis ability. The activity of calpains, especially μ-calpain, is closely related to the tenderness of muscles. The objective of this study was to investigate the activation process and the autolysis rate of μ-calpain in mutton during postmortem aging by analyzing and comparing the differences of calpain in mutton with different levels of tenderness, thereby provide a theoretical basis for regulating tenderness through regulating calpain activity. 【Method】 The longissimus dori of WuZhuMuQin Fat Tailed sheep were divided into tender group and tough group based on myofibrillar fragmentation index, then the pH value, the existent state of μ-calpain large subunit and the content of native μ-/m-calpain during postmortem were analyzed. 【Result】The variation trend of pH at postmortem in tender/tough group was identical, all the pH values in two groups at the same postmortem time showed no difference. The 80 kDa subunit of μ-calpain degraded gradually after slaughter. The content of μ-calpain 80 kDa subunit of tender group was significantly higher than tough group at 30 min postmortem. The intact 80 kDa subunit of μ-calpain could not be detected after 48 h in tender group, while it could be detected until 5 d postmortem in tough group. The content of native μ-calpain was decreased gradually, and this content of tender group was significantly higher than tough group at 30 min, 2 h postmortem, however, at 12 h, 5 d, and 7 d postmortem the tough group was significantly higher than the tender group. The autolysis and degradation of μ-calpain in tender group was apparent at 6 h postmortem.【Conclusion】Compared with tough group, tender group had a higher initial μ-calpain content, but the autolysis and degradation rate of μ-calpain in tender group was much faster, leading higher autolysis and degradation degree in tender group. The results indicated that meat tenderness during the postmortem was directly affected by μ-calpain expression quantity and autolysis. In addition, changes of μ-calpain during 24 h postmortem, especially 12 h, had the most impact on mutton tenderness. Reference | Related Articles | Metrics

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The Mechanism of Myosin Phosphorylation Regulating Actomyosin Dissociation of Skeletal Muscle During Postmortem GAO Xing, LI Xin, LI Zheng, DU Man-ting, ZHANG Cai-xia, ZHANG De-quan, DING Wu Scientia Agricultura Sinica    2016, 49 (16): 3199-3207.   DOI: 10.3864/j.issn.0578-1752.2016.16.013 Abstract （373）   HTML （1）    PDF （2698KB）（497）       Knowledge map    Save 【Objective】The aim of this study was to investigate the effect of myosin phosphorylation modification on actomyosin dissociation by analyzing the correlation between myosin phosphorylation and actomyosin dissociation, and then reveal the function of myosin phosphorylation to sarcomere length and tenderness during postmortem.【Method】Samples of ovine longissimus dorsi after storage at 4℃ for 6, 24, 48, 72 h were collected for myosin phosphorylation and actomyosin dissociation by SDS-PAGE, Pro-Q Diamond staining and western blotting, actomyosin ATPase activity. And sarcomere length was measured by transmission electron microscope.【Result】The phosphorylation level of myosin light chain 2 decreased sharply from 0.5-48 h (P＜0.05), then it increased from 48-72 h, and the final value was lower than the initial phosphorylation value. While to the dissociation of actomyosin, it displayed a gradual decrease from 0.5-6 h and then increased from 6-48 h (P＜0.05), finally kept stable during 48-72 h postmortem, and the final dissociation degree was significantly higher than 0.5 h. The actomyosin ATPase activity increased to the highest value at 24 h, followed by gradual decrement from 24 to 72 h. On the contrary, the sarcomere length decreased to the shortest value at 24 h, followed by gradual sarcomere relaxation from 24 to 72 h.【Conclusion】The phosphorylation level of myosin light chain 2 had a great influence on myosin and actin interaction, in addition, the sarcomere contraction (myosin and actin interaction force) and the dissociation of actomyosin (myosin and actin interaction amount) happened out of sync during postmortem. Phosphorylation modification of myosin light chain 2 caused the sarcomere shrinkage and relaxation by negative regulating actomyosin dissociation and actomyosin ATPase activity negatively, which could control the final meat tenderness. Reference | Related Articles | Metrics

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The Odor of Rabbit Meat Extracted by Supercritical Carbon Dioxide Fluid Extraction XIE Yue-jie, HE Zhi-fei, LI Hong-jun Scientia Agricultura Sinica    2016, 49 (16): 3208-3218.   DOI: 10.3864/j.issn.0578-1752.2016.16.014 Abstract （337）   HTML （2）    PDF （593KB）（697）       Knowledge map    Save 【Objective】The aim of this study was to explore the conditions for extracting the odor of rabbit meat by supercritical carbon dioxide fluid extraction (SFE-CO2), to determine the species, components and contents of rabbit meat odor and to provide the database for further deodorization and processing industry. 【Method】 SFE-CO2 technology was employed to extract the odorants in rabbit meat with Box-Behnken response surface analysis based on single factor experiments, using extraction yield as a target. The odorants of rabbit meat were detected by gas chromatograph in tandem with mass spectrum, with 2, 4, 6-trimethylpyridine (TMP) as an internal standard. Calculating odor active value (OAV) of the detected matters, and combining with gas chromatography olfactory (GC-O) and sensory evaluation, the main contents of rabbit meat odor was determined.【Result】The results of single factor experiment indicated that the extraction yield could reach 97.91% and the peak areas were 1.58×109 when the extraction temperature was 40℃. When the extraction time was 4 hours, the extraction yield and peak areas were 97.83% and 2.42×109, respectively. The extraction rate reached 97.78% with peak areas of 3.78×108 when the extraction pressure was 25 MPa. Among the three factors, the extraction temperature and extraction pressure not only affected the solute diffusion coefficient, but also the density of CO2 fluid. The diffusion coefficient increased when the extraction temperature was raised, but the extraction yield decreased due to the decreased CO2 fluid density. Although the density of CO2 fluid was larger at higher extraction pressure, the compressibility decreased. Hence, the extraction yield decreased due to the reduction of diffusion coefficient and solubility. When the extraction time was too long, the proportion of the odorants was reduced, for some non-volatile compounds were extracted, with the total amount increased. According to the response surface analysis, it was concluded that the optimal extraction temperature, extraction pressure and extraction time were 40.67℃, 25.67 MPa and 3.13 h, respectively, with extraction yield reached 98.01%. And the actual operation showed that the extraction temperature, extraction pressure and extraction time were 40℃, 25 MPa and 3 h, respectively. Under these conditions, the extraction yield was 98.11%. Through quantitatively adding internal standard substance TMP, GC - MS quantitatively analyzed for rabbit meat volatile flavour compounds of five classes, including aldehydes, acids, esters, heterocyclic compounds and hydrocarbons, a total of 38 kinds of flavor compounds. Comparing the five types of matter content: acids ((1 394.25±3.45) μg·kg-1) > esters ((569.26±1.23) μg·kg-1) > hydrocarbon ((471.82±1.11) μg·kg-1) > aldehyde ((168.46±0.97) μg·kg-1) > heterocyclic ((86.71±0.64) μg·kg-1). The key odorants of rabbit meat odor were pentanal, hexanal, hexanoic acid and 2-pentyl furan via calculating OAV. Those four materials with liver off-flavor, grass odor, muttony odor and beany odor respectively were regarded as the main bodies of odor in rabbit meat by GC-O. In addition, the extractant showed rabbit meat odor obviously through sensory evaluation.【Conclusion】The method of SFE-CO2 which provides a new extraction way for researching rabbit meat odor is feasible. The optimal extraction temperature, extraction time and extraction pressure was 40℃, 3 h, 25 MPa. Pentanal, hexanal, hexanoic acid and 2-pentyl furan were preliminarily regarded as the main bodies of rabbit meat odor. Reference | Related Articles | Metrics

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Preparation and Antimicrobial Activity of Cottonseed Protein Hydrolysate HAN Xiao-yan, BAO Yu-ming, XIN Feng-jiao, KONG Zhi-qiang, Christophe Blecker, DAI Xiao-feng Scientia Agricultura Sinica    2016, 49 (15): 3019-3029.   DOI: 10.3864/j.issn.0578-1752.2016.15.016 Abstract （491）   HTML （3）    PDF （3211KB）（917）       Knowledge map    Save 【Objective】 In order to provide a theoretical basis and technical support for efficient utilization of cottonseed protein, two methods were used to prepare cottonseed protein, then the isolated proteins were compared and digested in vitro by pepsin and trypsin, lastly the hydrolysates were detected and selected in antibacterial activity. 【Method】 In this paper, cottonseed protein isolate was prepared by the traditional method which is alkali extraction and acid precipitation and Osborne fractionation method. The protein content and molecular weight of the obtained proteins were determined by the Kjeldahl method and Tricine-SDS-PAGE respectively, microstructure of the proteins were examined by scanning electron microscopy. Amino acid composition of cottonseed proteins were analyzed by automatic amino acid analyzer (L-8900). And then proteins were digested by pepsin and trypsin in vitro in the process of digestination, the degree of hydrolysis (DH) of cottonseed protein isolate (CPI) and cottonseed globulin (CPG) hydrolysates were determined by ortho-phthalaldehyde (OPA), and then kanamycin (Kan) and protein solution without hydrolysis were used as control to determine the antibacterial activity of protein hydrolysates with Staphylococcus aureus and Escherichia coli bacteria. Meanwhile, the molecular weight distribution of the hydrolysis products were detected by high performance liquid chromatography (HPLC). 【Result】The extraction rate of CPI by the method of alkali extraction and acid precipitation was (70.52±2.40)% and its protein content reached (89.53±0.66)%. While the albumin, globulin, prolamin and glutelin were classified by Osborne fractionation method, and compared with the other three proteins, cottonseed globulin got the highest protein content that was (82.57±1.02)%. And there was no significant difference (P＞0.05) in protein extraction rate between the two preparation methods for the proteins extraction rate of Osborne fractionation method was (67.55±1.16)%. The Tricine-SDS-PAGE pattern showed that the subunits composition of CPG was more closely to CPI, compared to the other obtained proteins by Osborne fractionation method. The microstructures of the obtained proteins were different from each other. The structure of CPI showed a neat honeycomb structure, which was similar to glutenins’ microstructure, while the CPG showed a uneven granulated one. Amino acid composition analysis indicated that the amino acids of CPG were well maintained by Osborne method, compared to CPI. Cottonseed proteins were hydrolyzed by pepsin and trypsin simulated the digestive system in vitro. The hydrolysis degree of cottonseed protein hydrolysates was determined by microplate reader, and the result showed that the degree of hydrolysis of CPI hydrolysates was higher than CPG at the same amount of added enzyme, which indicated that CPI was easier to be hydrolysed than CPG. The molecular weight of cottonseed protein hydrolysates was measured by HPLC, and the result showed that the content of peptides (MW≤0.8 kDa) of CPI hydrolysates was significantly higher than CPG with the content of 70%-85% and 40%-60%, respectively. Results of antibacterial activity analysis showed that the antibacterial ability of these protein hydrolysates were strongest when the amount of pepsin-trypsin in digestion simulation system was 5 000-5 000 U (2-2), and the degree of hydrolysis of these protein hydrolysates were (24.72±1.07)% and (19.26±0.39)%, respectively, under such digested conditions, and the ability of both digestions to against E. coli were higher than S. aureus. CPI was higher than CPG in antibacterial activity, while both of the original protein without digestion treatment showed no antibacterial ability. The molecular weight determination results showed that the molecular weight of antibacterial activity peptides of cottonseed protein isolate should be in 0.57-0.75 kDa while cottonseed globulins’ were in 0.66-0.78 kDa.【Conclusion】 There was no significant difference between the two methods in the extracted yield of protein (P＞0.05), proteins classified by Osborne fractionation method showed an obvious difference in subunit composition, but the CPG and CPI showed a similarity. CPI is easier to be digested compared to the CPG and both of these two proteins’ hydrolysates showed an antibacterial activity, the hydrolysates of CPI is higher than CPGs’ in antibacterial activity. Reference | Related Articles | Metrics

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Profile Analysis of the Volatile Flavor Compounds of Quantitative Marinated Chicken During Processing SUN Zhen, HAN Dong, ZHANG Chun-hui, LI Hai, LI Xia, LIU Zhi-bin, XU Shi-ming Scientia Agricultura Sinica    2016, 49 (15): 3030-3045.   DOI: 10.3864/j.issn.0578-1752.2016.15.017 Abstract （536）   HTML （9）    PDF （2248KB）（695）       Knowledge map    Save 【Objective】This research was conducted to study the compositions and contents of volatile flavor compounds during quantitative marinating process and the taste characteristics of flavor substances in detail. The study was expected to provide theoretical supports to the flavor control technology of quantitative marinating.【Method】 The headspace-solid phase micro- extraction combined with gas chromatography-mass spectrometry (HS-SPME/GC-MS) was used to determine the components and contents of volatile flavor compounds from raw chicken meat, four stages of quantitative marinating process (tumbling, baked 1, steamed, baked 2) and traditional marinating by qualitative and quantitative methods, to calculate odor activity values of the volatile flavor substances by the odor threshold in the water, to determine characteristic flavor substances, main flavor substances and modify flavor substances, then the odor activity value of volatile compounds was analyzed by principal component analysis (PCA) and cluster analysis (CA) procedures.【Result】The results indicated that 54, 60, 60, and 60 kinds of volatile flavor compounds were identified from quantitative marinating process, which were higher than 9 kinds of volatile flavor compounds in the raw and 44 kinds of volatile flavor compounds from traditional marinating. Quantitative analysis revealed that the volatile flavor compounds at tumbling phase mainly from spice liquid. Chicken thigh at baked 1 stage began to appear characteristic flavor substances trans, trans-2,4-decadienal, 1-octene-3-ol and so on, the contents of volatile flavor compounds were the highest at steaming stage, and chicken thigh meat was matured by steaming at this stage, the main stage for the formation of flavor. The contents of total volatile flavor compounds of chicken thigh quantitative marinated at baked 2 stage was much higher than traditional marinating, explaining that quantitative marinating is more intense than traditional marinating in flavor presenting. The characteristic flavor compounds were mainly hexanal, octanal, nonanal, (E)-2-nonenal, (E, E)-2,4-decadienal, (E,E)-2,4-nonadienal, benzeneacetaldehyde, eucalyptol and β-myrcene from quantitative marinated chicken thigh during processing, and the odor activity value of them were significantly higher than that of raw meats and traditional marinated chicken. The main flavor compounds were mainly octanal, (E)-2-decenal, (E, E)-2,4-decadienal, 1-octen-3-ol and β-linalool from quantitative marinated chicken thigh during processing. The modified flavor compounds were mainly ketones, esters and alcohols from quantitative marinated chicken thigh during processing. By principal component analysis and clustering analysis, there were significant differences in odor outline from raw chicken meat, four stages of quantitative marinating process and traditional marinating, and the main flavor compounds clustered into four categories, and each category has characteristic flavor compounds represented quantitative marinating process.【Conclusion】 The flavor profile results showed that compositions and development laws of flavor active substances stewed chicken, comparing with traditional marinating, quantitative marinating can present volatile flavor compounds better. Reference | Related Articles | Metrics Cited: Baidu(2)

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Gel Model and Mechanism of Low-Methoxyl Apple Pectin for Various pH HAN Wan-you, DONG Gui-ru, QU Yu-ling MENG Yong-hong, GUO Yu-rong, DENG Hong Scientia Agricultura Sinica    2016, 49 (13): 2603-2611.   DOI: 10.3864/j.issn.0578-1752.2016.13.016 Abstract （478）   HTML （1）    PDF （2025KB）（578）       Knowledge map    Save 【Objective】The mathematical model of LM apple pectin gel strength which were prepared by citric acid - disodium hydrogen phosphate buffer solution were established with pH 1.78-6.62 and the mechanism of gelling was analyzed by data of rheology. The results of this study will provide a theoretical reference for the application of LMP in different pH environments. 【Method】Gel strength, rupture strength and rheological properties were measured by texture analyzer and rheometer, respectively. A model was established with Mate lab 10.0. According to the sol-gel transition point in graphs which was combined with storage shear modulus and loss shear modulus intersections in the graph, the pH range of gels could be determined. The mechanism of gels under different pH was analyzed on the basis of changes in storage shear modulus and loss shear modulus in the graph and the structure characteristics.【Result】The model of gel strength was followed by the polynomial law. In the range of pH 1.78-3.10, hydrophobic interactions between methoxyl ester groups and hydrogen bonds among undissociated carboxyl groups were formed which resulted in the sol to gel transition and gel strength to 21.19 g. When the pH of pectin solution was about 3.10, hydrophobic interactions between methoxyl ester groups and hydrogen bonds between undissociated carboxyl groups were formed. So that the elastic modulus increased significantly, the gel strength was about 21.00 g. In this pH range, although the pectin charge density was low, Ca2+ was still promoted the gel. However, the dissociation of carboxyl anion concentration could not reach the optimal amount of electronegativity carboxyl to form a stable “egg box”, gels were not so stable. In the range of pH 3.10-4.20, Calcium Bridge were formed between galacturonic acid residues and Ca2 +, which made gel tend to be stable and gel strength near to 22.00 g. In the range of pH 4.20-6.62, the electrostatic repulsion was predominant between pectin chains, which generated pectin gradually depolymerization because of free dissociated -COO- reached a maximum.【Conclusion】In the pH range of 1.78-6.30, LMP could form gels. When pH was in the range of 1.78-3.10, the pectin could be used at strongly acidic conditions and suitable for higher acidity of foods and medicines. When pH was in the range of 3.10-4.20, the stable gels could meet the food requirements of higher food gel texture. The results of this study have practical significance for the application of low methyl ester pectin in food with different pH ranges. Reference | Related Articles | Metrics

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The Preparation Process for Isolation of a Highly Active Antioxidant Peptide Derived from Wheat Germ Albumin CHEN Si-yuan, LIU Yong-xiang, CAO Xiao-zhou, ZHANG Yi-jing, CHEN Hai-juan, SHEN Xin-chun Scientia Agricultura Sinica    2016, 49 (12): 2379-2388.   DOI: 10.3864/j.issn.0578-1752.2016.12.013 Abstract （399）   HTML （2）    PDF （808KB）（550）       Knowledge map    Save 【Objective】 The aim of this study is to develop an effective preparation process for obtaining highly active antioxidant peptide derived from wheat germ albumin using two-step dual-enzymatic hydrolysis. 【Method】 A two-step dual-enzymatic hydrolysis and separation were employed to screen the antioxidant peptide (AOP) from wheat germ albumin. The in vitro AOP’s antioxidant activity was evaluated by DPPH radical scavenging activity and Fe2+ chelating ability assays. The hydrolysate derived from tryptic hydrolysis of wheat germ albumin was fractionated by ultrafiltration according to molecular weight; then the fractions with high antioxidant capacity were further isolated by gel filtration chromatography (Sephadex G-75). After that, the fraction with higher antioxidant activity was further hydrolyzed by an alcalase, and the hydrolysate was subjected to purification by Sephadex G-15 gel filtration chromatography and reversed-phase HPLC (RP-HPLC), respectively. The highest antioxidant fraction was achieved and the structure was identified by ESI-TOF MS/MS. 【Result】 Hydrolysate derived from tryptic hydrolysis of wheat germ albumin was fractionated by ultrafiltration according to molecular weight. Three fractions, Pa, Pb and Pc were obtained from the fraction with high antioxidant capacity. The fraction Pb showed the strongest antioxidant activity evaluated by DPPH radical scavenging activity and Fe2+ chelating ability assays and its extraction yield was 23.1%. The fraction Pb which had the highest antioxidant activity was further hydrolyzed by an alcalase, and the hydrolysate was subjected to gel filtration chromatography (Sephadex G-15) and two more groups, Pd and Pe were obtained. The extraction yield of fraction Pd which had higher antioxidant capacity was 52.1%. After further purification by RP-HPLC, five fractions, P1, P2, P3, P4 and P5 were separated from the fraction Pd, and the fraction P3 exhibited the highest antioxidant activity with the in vitro EC50 values of DPPH radical scavenging activity at 1 mg/ml and Fe2+ chelating ability at 0.6 mg/ml, respectively. The extraction yield of the fraction P3 was 7.3% in RP-HPLC step. Finally, employing the electrospray ionization-time-of-flight mass spectrometer (ESI-TOF MS/MS), the structure of the fraction P3 was identified. Its amino acids sequence, molecular weight and purity were AREGETVVPG, 1013.51Da and 85%, respectively. Consistently, the antioxidant capacity of the synthetic peptide with the same sequences ( purity ≥95%) showed the similar activity to the fraction P3 (P>0.05). 【Conclusion】 The preparation process of a two-step dual-enzymatic hydrolysis in combination with ultrafiltration, gel filtration chromatography, and RP-HPLC was effective in separation, screen and purification of a highly active antioxidant peptide. Reference | Related Articles | Metrics Cited: Baidu(1)

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Investigation and Analysis of Main Antinutritional Factors in Soybean and Extruded Soybean YAO Yi-sha, GU Xu, SHANG Fang-fang, QIU Jing, LI Jun-guo1, LI Jun Scientia Agricultura Sinica    2016, 49 (11): 2174-2182.   DOI: 10.3864/j.issn.0578-1752.2016.11.013 Abstract （594）   HTML （9）    PDF （390KB）（1526）       Knowledge map    Save 【Objective】Soybean is an important food material as well as feed material for its abundant nutriments, but some antinutritional factors (ANFs) in soybean limit its application in the food and feed industries. As a widely used processing technique, the extrusion process can reduce the side-effect of ANFs in soybean to human and animals causing the content of ANFs to decrease while the content of nutrient composition remains about the same. This research is aimed at investigating and analyzing the difference of main antinutritional factors in soybean and extruded soybean and discussing the effect of the extrusion process to these ANFs in soybean, so as to provide a reference for expanded enterprises to choose high quality raw materials and optimize the processing technique in the actual production, and provide some guidance to the design of animal feed formula. 【Method】In this research, 20 batches of soybean and 19 batches of extruded soybean from different areas of the manufacturer were collected, and the content or activity of the main anti-nutritional factors, including trypsin inhibitor, antigenic protein (glycinin and β-conglycinin), oligosaccharide (raffinose and stachyose) and urease, were detected. And these results were compared with 2 batches of soybean and 8 batches of extruded soybean that were produced in one manufacturer. The concentrations of trypsin inhibitor and antigenic protein were analyzed using ELISA. The concentrations of oligosaccharide were determined by HPLC with a differential detector. At the same time the extraction methods of oligosaccharides were optimized. Single factor optimize experiments were the way of extraction, the dosage of activated carbon, volume percentage of ethanol, and solid-liquid ratio. The solution was detected by HPLC after through filter membrane. Through comprehensive analysis of the data, the effect of extrusion technology on the content or activity of main antinutritional factors in soybean was studied. 【Result】 The extraction method is as follows: adding 70% ethanol solution to the samples (solid-liquid ratio: 1﹕25), and then centrifuging and concentrating the extracting solution after using microwave assisted extraction, diluting the concentrated solution with water to 25 mL, centrifuging the solution (2 mL) after blending. In comparison the content of the main antinutritional factors in soybean (22 batches) with the content in extruded soybean (27 batches), the content of trypsin inhibitor and antigenic protein and urease activity in soybean is significantly lower than those in extruded soybean while the content of oligosaccharides has no significant difference between them. The urease activity of most of extruded soybeans is near zero and lower by 99% than the activity of soybeans. The content of trypsin inhibitor, glycinin and β-conglycinin decreased respectively in 66%, 67% and 90%, while the content of raffinose and stachyose remained largely unchanged. From this research the content or activity of trypsin inhibitor, glycinin, β-conglycinin, raffinose, stachyose and urease in the soybean is respectively 32.5-89.6 mg·g-1, 91.0-143.1 mg·g-1, 161.1-268.7 mg·g-1, 3.3-8.78 mg·g-1, 21.4-34.16 mg·g-1 and 3.6-9.42 U·g-1, in the extruded soybean is respectively 10.7-31.1 mg·g-1, 17.7-64.5 mg·g-1, 9.3-57.5 mg·g-1, 4.25-10.21 mg·g-1, 17.68-34.15 mg·g-1 and 0.00-0.02 U·g-1. 【Conclusion】 The extrusion process can significantly reduce the content of the main antinutritional factors in soybean and side effects caused by these factors and can improve the utilization rate of nutrition. This study presents the reference range of the main ANFs in content or activity in soybean and extruded soybean. Reference | Related Articles | Metrics Cited: Baidu(6)

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Chemical Compositions and Physicochemical Properties of Milk Fat and Fractions Obtained by Short-Path Distillation GAO Xi-xi, ZHANG Shu-wen, LU Jing, LIU Lu, PANG Xiao-yang, YUE Xi-qing, Lü Jia-ping Scientia Agricultura Sinica    2016, 49 (11): 2183-2193.   DOI: 10.3864/j.issn.0578-1752.2016.11.014 Abstract （447）   HTML （3）    PDF （1521KB）（275）       Knowledge map    Save 【Objective】Milk fat is not suitable for some food applications and has limited functionality because of its complex compositions, structures and processing properties. The objective of this study is to provide a technical method and theoretical reference for fractionation of milk fat through studying the chemical compositions and physicochemical properties and its correlation of milk fat and fractions obtained by short-path distillation in different distillation temperatures.【Method】Commercial milk fat was fractionated by short-path distillation at 150℃, 165℃, 180℃, 190℃, 200℃, 210℃, 225℃, and 240℃, respectively, and the relationship of distillation temperature and yield of distillate was analyzed. Fatty acid composition was determined by gas chromatography to study the effect of distillation temperature on the composition and properties of milk fat and its fractions. Acid value, iodine value, peroxide value, slipping melting point, DSC thermograms of melting and crystallization and polarized light micrographswere also measured.【Result】The lowest temperature that milk fat could be fractionated was 165℃. Distillate yield increased from 1.19% to 36.89% with the distillation temperature increased from 165℃ to 240℃. Acid and peroxide value of distillate and retentate obtained by short-path distillation had different changes with no regularity, while the iodine value of retentate was generally higher than that of distillate. Short-path distillation did not change the kinds of fatty acids in the fractions, but the concentration of certain fatty acid presented substantial differences: the distillate was enriched in short- and medium-chain fatty acids (40%-60%), while the retentate was enriched in long-chain fatty acids (65%-75%) and unsaturated fatty acids (about 30%), which was consistent with the result of iodine value. Distillation temperature had a significant effect on the content of fatty acids in the fractions and the concentration of all kinds of fatty acids showed a trend of approaching to milk fat with the increase of distillation temperature. Relative to milk fat, the slipping melting point of the distillate was depressed and that of the retentate was augmented, while both of them showed an increasing trend as the distillation temperature increased. There was a significant positive correlation (P＜0.01) between the concentration of long-chain fatty acids in the fractions and their slipping melting point, r=0.977. DSC results showed that the melting and crystallization peaks of fractions were offset to the high temperature area as the increase of distillation temperature which indicated that the melting and crystallization properties of fractions were different but changed regularly. Polarized light micrographs showed that the distillate and retentate had different fat crystals, the crystals formed on cooling at 5℃ for 24 h corresponded to spherulites for the retentate whereas the solid fat phase of the distillate corresponded to needle-shape crystals. 【Conclusion】 Milk fat could be fractionated effectively by short-path distillation and distillation temperature had a significant effect on the resulting fractions. Fractionation of milk fat by short-path distillation at different distillation temperatures is able to change the chemical compositions, physicochemical properties and processing properties of the fractions. Reference | Related Articles | Metrics

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Influence of Addition of Unsaturated Fatty Acids on Fatty Acid Composition of Saccharomyces cerevisiae and Wine Aroma Compounds DUAN Liang-liang, PAN Qiu-hong, WANG Ya-qin, YE Dong-qing, DUAN Chang-qing, YAN Guo-liang Scientia Agricultura Sinica    2016, 49 (10): 1960-1978.   DOI: 10.3864/j.issn.0578-1752.2016.10.012 Abstract （546）   HTML （4）    PDF （900KB）（1550）       Knowledge map    Save 【Objective】To provide a theoretical basis for improving the quality of wine, the effect of different concentrations of unsaturated fatty acids (UFAs, including oleic acid, linoleic acid, and α-linolenic acid) in grape juice on the intracellular fatty acid composition of yeast and volatile profile in wine were investigated in this study.【Method】 Different concentrations of mixed UFAs were initially added into ‘Merlot’ (Vitis vinifera L.) juice including the control without UFAs addition (CK),low concentration of UFAs addition (LFG) and high concentration of UFAs addition (HFG). The growth of yeast (Saccharomyces cerevisiae EC1118) growth (OD600), intercellular fatty acid composition and wine volatile aroma compounds among the three treatments during alcoholic fermentation were compared.【Result】The increase of UFAs can accelerate yeast growth and promote UFAs absorption by yeast, while suppress yeast saturated fatty acids (C4:0-C24:0) synthesis. The influence of UFAs on wine aroma showed that the increase of UFAs can stimulate the production of higher alcohols and ethyl esters by yeast, such as ethyl hexanoate, ethyl octanoate and ethyl decanoate, but inhibit the generation of medium-chain fatty acids (MCFAs, C4:0-C12:0). The influence on grape-derived aldehydes, monoterpenes and norisoprenoids volatiles were little. 【Conclusion】 Increasing UFAs in grapes can considerably improve yeast growth and the wine fermentation rate, more importantly, it can promote yeast-derived ethyl esters volatiles production, which intensifies the fruity, flowery and sweet odors of wine. Therefore, manipulation of initial UFA contents in grapes or grape juice is a potential way to regulate wine aroma quality. Reference | Related Articles | Metrics

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Effect of Lactic Acid Bacteria Fermentation on Phenolic Profiles and Antioxidant Activity of Dried Longan Flesh LAI Ting, LIU Lei, ZHANG Ming-wei, ZHANG Rui-fen, ZHANG Yan, WEI Zhen-cheng, DENG Yuan-yuan Scientia Agricultura Sinica    2016, 49 (10): 1979-1989.   DOI: 10.3864/j.issn.0578-1752.2016.10.013 Abstract （640）   HTML （3）    PDF （403KB）（1106）       Knowledge map    Save 【Objective】 The effect of lactic acid bacteria fermentation on free and bound phenolics and flavonoids and on antioxidant activity of dried longan flesh was investigated, with the purpose of giving some technical guidance for the deep processing of dried longan, and the development of new nutrition and health products fermented by lactic acid bacteria. 【Method】The culture medium was longan fruit pulp (the dried longan flesh: water=1:1.5), which then was inoculated by seven strains (Lactobacillus acidophilus GIM 1.731, Leuconostoc mesenteroides GIM 1.473, Lactobacillus casei GIM 1.411, Pediococcus pentosaceus GIM 1.428, Lactobacillus plantarum subsp. plantarum GIM 1.380, Lactobacillus delbrueckii subsp. lactis GIM 1.407, Lactobacillus bulgaricus GIM 1.155, bacteria concentration: 8.0-9.0 lg CFU/mL) with 1% at 37℃ for 48 hours. The contents of free and bound phenolics and flavonoids in dried longan flesh were determined. A high performance liquid chromatography (HPLC) method was used to measure the compositions and contents of phenolics in dried longan flesh. The antioxidant activity was analyzed using the ferric reducing ability of plasma (FRAP) and Oxygen Radical Absorption Capacity (ORAC). 【Result】 Seven lactic acid bacterias can increase, to different extents, the content of free phenolics and flavonoids in dried longan flesh (P＜0.05), and reduce the content of bound phenolics and flavonoids (P＜0.05). Compared to the no fermentation group, the content of free phenolics increased by 0.4%-11.9%, the content of bound phenolics decreased by 14.4%-41.4%; the content of free flavonoids increased 2.8%-19.6%, and the content of flavonoids decreased by 19.6%-70.6%. Lactobacillus plantarum subsp. plantarum GIM 1.380 had more advantages than other lactic acid bacteria on the ability of releasing bound phenolics, The content of free phenolics increased by 11.9%, the content of bound phenolics decreased by 41.4%, the content of free flavonoids increased by 19.6%, and the content of flavonoids decreased by 70.6%. Different lactic acid bacteria had different influence on phenolics compositions in dried longan flesh (gallic acid, syringic acid, (-)-Epicatechin, 4-methylcatechol, protocatechuic acid, p-coumaric acid, and isoquercetin). Compared to the no fermentation group, the content of free gallic acid and 4-methylcatechol were increased by 8.6%-69.8% and 0.4%-29.5%, and the content of bound gallic acid, vanillic acid and 4-methylcatechol were decreased by 80.0%-88.3% and 45.6%-73.9%. After fermentation, the free FRAP value and ORAC value were obviously increased (P＜0.05), compared with the no fermentation group. 【Conclusion】 Lactic acid bacteria fermentation could increase the content of free phenolics in dried longan flesh, and reduce the content of bound phenolics, as well as improve its free antioxidant activity. Different lactic acid bacteria fermentations had differently effects on the total phenolic contents and antioxidant capacity and phenolic compositions in dried longan flesh. The result indicated that Lactobacillus plantarum subsp. plantarum GIM 1.380 had more advantages than the other lactic acid bacteria in the ability of releasing bound phenolics and improving antioxidant ability. Reference | Related Articles | Metrics Cited: Baidu(1)

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Present Situation and Prospect of Potato Processing in China MU Tai-hua, CHEN Jing-wang Scientia Agricultura Sinica    2016, 49 (9): 1744-1745.   DOI: 10.3864/j.issn.0578-1752.2016.09.010 Abstract （764）   HTML （28）    PDF （222KB）（1703）       Knowledge map    Save Reference | Related Articles | Metrics

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Domestic and Abroad Research Progress of Potato Tuber-Specific Storage Protein Patatin ZHANG Du-qin, MU Tai-hua, SUN Hong-nan Scientia Agricultura Sinica    2016, 49 (9): 1746-1756.   DOI: 10.3864/j.issn.0578-1752.2016.09.011 Abstract （658）   HTML （15）    PDF （446KB）（819）       Knowledge map    Save Potatoes are the fourth main crops after wheat, rice, and corn. China is the world’s largest potato production country. Along with the development of the potato processing industry, studies on potatoes are going on gradually. Patatin is the potato tuber-specific storage protein, as well as the main part of the potato protein. In addition to its Lipid acyl hydrolase (LAH) and antioxidant activity, Patatin has excellent physico-chemical and functional properties such as solubility, emulsifying, foaming, and gelling properties, and is one of the most popular vegetable proteins. However, no overviews about the physico-chemical properties, the isolation, extraction and purification methods, the application in the food industry, and the future research hotspots of patatin were found up to now. In this paper, the molecular weight, structural characteristics, and physico-chemical properties of patatin were introduced, the method of isolation, extraction, and purification methods of patatin were summarized, and the advantages and disadvantages of each method were compared in order to provide a theoretical reference for the further application, research, and exploitation of patatin in the food industry. The content of patatin in potato protein ranged from 5.4% to 38.0%, relating to the cultivars and metabolic physiology of potato. The molecular weight of patatin varied from 39 kDa to 45 kDa, depending on the degree of glycosylation. Patatin is a kind of globulin with compact structure, and the primary structure contains more than 360 amino acid residues and remained unaffected by the surrounding elements, while the advanced structures were affected by temperature, pH, and so on. Patatin has excellent physico-chemical and functional properties such as solubility, emulsifying, foaming, and gelling properties, which were affected by surrounding elements. Gel chromatography and ion-exchange chromatography are the most common methods to isolate and purify patatin from potato protein, the reversed-phase chromatography (RPC), immunoaffinity chromatography, and gene expression can produce highly purified patatin. Although not suitable for large-scale production, expanded bed adsorption (EBA) chromatography can prepare large amount of patatin with low purity. Research studies on the application of patatin in the food industry are scarce. Patatin has great potential as food ingredients in the food industry, further research studies on Patatin will continue progress toward simplifying extraction methods, cutting the extraction cost, and developing foods, health products, and drugs with high-functional value. Reference | Related Articles | Metrics Cited: Baidu(11)

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Establishment of a Viscosity Reduction Process by Enzymatic Pretreatment and Its Application in Ethanol Fermentation from Fresh Sweet Potato Without Adding Water YUE Rui-xue, NIU Fu-xiang, SUN Jian, XU Fei, WANG Hong-yun, ZHU Hong, ZHANG Yi Scientia Agricultura Sinica    2016, 49 (9): 1757-1766.   DOI: 10.3864/j.issn.0578-1752.2016.09.012 Abstract （395）   HTML （12）    PDF （404KB）（342）       Knowledge map    Save 【Objective】 The objective of this research was to establish a viscosity reduction process for fresh sweet potato (FSP) mash by enzymatic pretreatment before liquification and use it for direct ethanol fermentation from FSP without adding additional water. 【Method】 A total of 12 kinds of starch-type sweet potatoes (SP), widely cultured in China, were selected for this research. The main components of SP, such as dry matter, starch, protein, soluble sugars, pectin, hemicellulose, cellulose, and lignin, were detected and the correlation between these components and viscosity of FSP were analyzed. Based on the results, proper enzymes, cellulase and pectinase, were selected for viscosity reduction. Effects of some key factors of enzymatic pretreatment on viscosity reduction were investigated, including the ratio of substrate to water (1:0, 2:1, 3:2, 5:4, and 1:1), enzymatic pretreatment time (1, 2, 3, 4, and 5 h), enzymes doses (cellulase: 1.0, 1.5, 2.0, 2.5, and 3.0 GCU·g-1 and pectinase: 1.0, 1.5, 2.0, 2.5, and 3.0 U·g-1), and enzymatic pretreatment temperatures (30℃, 40℃, 50℃, 60℃, and 70℃). The optimum enzymatic pretreatment conditions were determined by orthogonal experiment design and the effects of enzymatic pretreatment on the following ethanol fermentation performance from FSP were also investigated. 【Result】 For 12 kinds of tested starch-type sweet potato varieties, except for hemicellulose (r=-0.239) and lignin (r=-0.069), all the components were positively correlated to the viscosity (dry matter content, r=0.356; starch, r=0.211, soluble sugar, r=0.307; protein, r=0.266; pectin, r=0.526; cellulose, r=0.600). Wherein the pectin (P＜0.01) and cellulose (P＜0.05) were significantly positively correlated to the viscosity. According to the range analysis, the factors affecting enzymatic treatment effects from high to low were enzyme dosage, the ratio of substrate to water, enzymatic treatment time, and temperature. Based on the experiment results and the consideration on the industrial application, the optimum enzymatic pretreatment conditions were determined as: the ratio of substrate to water 1﹕0, cellulase 1.5 GCU·g-1, pectinase 1.5 U·g-1, and 50℃ for 3 h. Besides Wansu 178, mash viscosity from other varieties after enzyme treatment was lower than 3 000 cp, and the viscosity reduction rate was 95.07%-99.31%. At the end of fermentation, the ethanol concentration from 11 kinds of SP varieties was higher than 12% (v/v), and the fermentation efficiency of 9 varieties reached more than 90%. 【Conclusion】 Pectin and cellulose are the main factors affecting the viscosity of SP mash. Fresh SP mash can be directly used for ethanol fermentation after enzymatic pretreatment without adding water. Reference | Related Articles | Metrics

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Lactic Acid Fermentation by Lactobacillus rhamnosus from Sweet Potato Residue LIU Yu-ting, WU Ming-yang, JIN Yan-ling, SHEN Wei-liang, FANG Yang, ZHAO Hai Scientia Agricultura Sinica    2016, 49 (9): 1767-1777.   DOI: 10.3864/j.issn.0578-1752.2016.09.013 Abstract （516）   HTML （10）    PDF （566KB）（715）       Knowledge map    Save 【Objective】Lactic acid fermentation process by Lactobacillus rhamnosus using sweet potato residue was studied in this paper in order to provide new technical strategy for utilization of sweet potato dregs.【Method】Firstly, the major elements of sweet potato starch residue were measured by elemental analyzer, meanwhile, there were four fermentation groups carried out with four different time points during the logarithmic growth phase of L. rhamnosus which was identified through OD value of bacteria, the optimal seed age was confirmed taking the fermentation efficiency of lactic acid production using liquid glucose culture as index of investigation. Then on this basis, the sweet potato dregs were used by L. rhamnosus through solid state fermentation (SSF) in the following research: firstly, the effects of inoculation amount,temperature, CaCO3 quantity, nitrogen sources on lactic acid production were investigated through single factor experiments. In addition, the effects of nitrogen sources on viable bacteria counts in fermenting mash after fermentation were studied also. Then the optimal combination was established by further orthogonal design.【Result】Element analysis results showed that sweet potato starch residue was full of C and H, with weight percentage content of 40.34% and 6.16%, respectively. The content of N was only 0.32%. Although C was quite rich in sweet potato starch residue, N was deficient comparatively, it was necessary to add N source to promote growth and metabolism of L. rhamnosus furthermore. The growth curve of L. rhamnosus identified by ODvalue showed that the OD value of L. rhamnosus increased rapidly after inoculated for 2 h, which means that the logarithmic growth phase began. The OD value wasn’t change approximately after 8 h, which means that the stationary growth stage began. It was confirmed that the logarithmic growth phase of L. rhamnosus was 2 h to 8 h. The fermentation efficiency was the highest, reached 92.39%, when the seed age got to 4 h, and the content of residual glucose was the lowest, reached 0.59 g·L-1, it was confirmed that the optimal seed age of lactic acid fermentation was 4 h. The results of batch single factor experiment through SSF showed successively: The highest fermentation efficiency of 83.87% reached at 10%. The highest fermentation efficiency of 85.55% reached at 37℃, when CaCO3 quantity ranged from 1% to 7%, the highest fermentation efficiency of 90.24% reached at 5%; the fermentation efficiency of urea group reached 91.01% among 4 kinds of inorganic nitrogen source; when urea quantity ranged from 0.4% to 1.6%, the highest fermentation efficiency of 94.13% reached at 0.8%, the viable bacteria counts were 4.32×108 cfu/g. Based on the results of single factor experiments above, the optimal CaCO3 quantity of 5% was suitable for neutralizing the lactic acid produced by initial sugar in fermentation system of 10%, so it was unnecessary to change the optimal CaCO3 quantity, and it wasn’t investigated in the next orthogonal design. Besides, adding cellulase as investigation factor, designing the orthogonal experiment with four factors and three levels. Then, the fermentation optimum conditions were obtained, which were: the inoculation size 10%, urea amount 0.8%, cellulose amount 0.4%, temperature 35℃, CaCO3 quantity 5%, fermentation efficiency and viable bacteria counts, respectively, reached (96.55±0.866)% and 3.04×108 cfu/g under these conditions. 【Conclusion】A low-cost, simple-process, high-efficiency process condition was established which was not only suitable for lactate industry but also beneficial to sweet potato starch processing farmers. Reference | Related Articles | Metrics

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Effects of NaCl Concentration and pH Value on the Emulsifying Properties of Sweet Potato Peptides CUI Shan-shan, MU Tai-hua, SUN Hong-nan, ZHANG Miao, CHEN Jing-wang Scientia Agricultura Sinica    2016, 49 (9): 1778-1786.   DOI: 10.3864/j.issn.0578-1752.2016.09.014 Abstract （412）   HTML （12）    PDF （745KB）（545）       Knowledge map    Save 【Objective】 The study aims to clear the effects of different NaCl concentrations and pH values on the emulsifying properties of sweet potato peptides and provide a theoretical basis for the application of sweet potato peptides in the food industry. 【Method】Microstructure, average particle size (d4,3), emulsifying activity, emulsifying stability, rheological property of emulsion and hydrophobicity of sweet potato peptides with different NaCl concentrations (0.2, 0.4, 0.6, 0.8 and 1.0 mol·L-1) and different pH values (3, 5, 7 and 9) were measured. 【Result】Compared with the sweet potato peptide emulsion without NaCl, when 0.2 mol·L-1 NaCl was added into the sweet potato peptide emulsion, d4,3 was increased from 54.19 μm to 59.70 μm, the emulsifying activity index was decreased significantly from 86.29 m2·g-1 to 56.35 m2·g-1 (P＜0.05), and the emulsion stability index was decreased from 14.84 min to 13.19 min. However, with the increase of NaCl concentration, the uniformity of sweet potato peptide emulsion was decreased, d4,3 was further increased from 59.70 μm to 69.72 μm, the emulsifying activity was decreased from 56.35 m2·g-1 to 32.32 m2·g-1, emulsifying stability was firstly increased and then decreased, reached a maximum of 15.55 min at 0.04 mol·L-1, the initial apparent viscosity was increased and exhibited shear-thinning phenomenon, and surface hydrophobicity activity was decreased. In addition, with the increase of pH value, the uniformity of emulsion was increased, d4,3 was decreased from 64.45 μm at pH 3 to 51.21 μm at pH 9, the emulsifying activity was increased from 3.99 m2·g-1 at pH 3 to 120.47 m2·g-1 at pH 9, the emulsifying stability was firstly increased and then decreased, reached a maximum of 29.13 min at pH 3, initial apparent viscosity was reduced and exhibited shear-thinning phenomenon, and the activity of surface hydrophobicity was increased. 【Conclusion】 Emulsifying properties of sweet potato peptides are closely related to the NaCl concentration and pH value. Addition of NaCl (≥0.2 mol·L-1) reduced the emulsifying activity and stability of sweet potato peptides, while the increase of pH value could effectively improve the emulsifying activity of sweet potato peptides. Reference | Related Articles | Metrics

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Identification of Purple Sweet Potato Color of Cultivar Ningzi No. 1 by HPLC-QTOF/MS and Its Effect on Preventing Obesity in High-Fat-Diet-Treated Rats ZHANG Yi, WANG Hong-yun, NIU Fu-xiang, SUN Jian, XU Fei, ZHU Hong, YUE Rui-xue Scientia Agricultura Sinica    2016, 49 (9): 1787-1802.   DOI: 10.3864/j.issn.0578-1752.2016.09.015 Abstract （492）   HTML （14）    PDF （1719KB）（480）       Knowledge map    Save 【Objective】Purple sweet potato are the main source for natural antioxidants. This study aims to identify the components of purple sweet potato color of cultivar Ningzi No. 1, and investigate the effectiveness of PSPC for the prevention of obesity and the regulatory mechanism of PSPC in obesity prevention.【Method】 Purple sweet potato color was analyzed using an Agilent 1290 series high-performance liquid chromatography connected to an Accurate-Mass Quadrupole Time-of-Flight/MS (HPLC-QTOF/MS). A pH-differential method was used to determine the total PSPC content. Eight-week-old male Sprague Dawley strain rats were fed on either a normal diet containing 11.4% fat, or a HFD containing 40% fat and intragastrically administered PSPC once a day. Body weights of the rats were measured every week after 6 h of fasting. Activities of serum glucose, triglyceride, and total cholesterol were determined using commercial kits. Serum leptin levels were measured using enzyme-linked immunosorbent assay kits. Expression of leptin and leptin receptor mRNAs in the hypothalamus were detected using Real-time Quantitative PCR. Expression of leptin and its downstream proteins in the hypothalamus were analyzed using Western blotting.【Result】Eleven constituents were separated. Based on previous reports, ten constituents were identified and Peak 1 was newly reported herein. The cyanidin 3-glucoside content of PSPC was 17.4%. After 6 weeks, we first examined the changes in body weight. Our data showed that the effect of middle-dose PSPC (371.6±16.3) g was better than low-dose PSPC (384.0±7.2) g, and the effect of high-dose PSPC (358.2±20.1) g was best. Obesity was prevented and glucose, triglyceride, and total cholesterol induced by the HFD were restored to near-normal levels. Compared with control group rats (2.29±0.28) ng·mL-1, the levels of serum leptin in HFD group rats significantly increased by 65.50%. Compared with HFD group rats (3.79±0.24) ng·mL-1, the levels of serum leptin in low (3.13±0.05) ng·mL-1, middle (2.84±0.12) ng·mL-1, and high-dose (2.64±0.06) ng·mL-1 PSPC group rats were significantly decreased. Both of leptin and leptin receptor mRNAs expression in the hypothalamus was upregulated in the different-dose PSPC group compared with that in the HFD group. High-dose PSPC preserved the leptin signaling capability, leading to a decrease in hypothalamic AMPK α activity.【Conclusion】The anti-obesity effects of high-dose PSPC were mediated via a regulation of leptin/AMPKα signaling in the hypothalamus. Reference | Related Articles | Metrics

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Effects of Sodium Carboxymethyl Cellulose on Adhesion Properties of Soybean Protein Isolate onto Porcine Bones ZHANG Yi-jing, CHEN Hai-juan, Lü Yi, LIU Yong-xiang, TANG Xiao-zhi, SHEN Xin-chun Scientia Agricultura Sinica    2016, 49 (8): 1550-1558.   DOI: 10.3864/j.issn.0578-1752.2016.08.012 Abstract （419）   HTML （1）    PDF （1090KB）（566）       Knowledge map    Save 【Objective】The effects of sodium carboxymethyl cellulose (CMC-Na) on the adhesion properties of soybean protein isolate (SPI) onto porcine bone were investigated by studying tensile bond strength, zero shear viscosity, secondary structure, hydrophobicity and scanning electronic microscopy (SEM) images. The aim of the research was to provide a basis for utilization of SPI adhesive in biomedical fields. 【Method】SPI adhesive prepared with/without CMC-Na was used to bond porcine bones in vitro and the effect of CMC-Na on tensile bond strength of SPI adhesive was measured using a tensile strength testing machine. The influence of CMC-Na on zero shear viscosity of the SPI adhesive was measured using a rheometer. The SPI adhesive with CMC-Na secondary structure was measured using circular dichroism spectra to determine the content of α-helix, β-sheet, β-turn and random coil. The influence of CMC-Na on hydrophobicity and surface morphology of SPI adhesive was measured using ANS (1-anilino-8-naphthalene sulfonate) fluorescent probe method and scanning electron microscopy (SEM), respectively. 【Result】 The tensile bond strength of the SPI adhesive increased with the increase of its concentration and reached a peak at a SPI adhesive concentration of 10%, then began to decline. The adhesive strength of 2% SPI with addition of a trace amount of CMC-Na (at 0.01%) was increased 2.4 fold (P<0.01) in comparison with the control. There was a significant positive correlation (r=0.815, P<0.05) between adhesive strength and zero shear viscosity. The addition of trace CMC-Na influenced significantly the secondary structure of the SPI adhesive. The β-sheet and β-turn content increased from 42.2% to 49.1% and from 2.1% to 7.3%, respectively, while the α-helix and random coil content declined from 28.0% to 19.7% and from 27.7% to 23.9%, respectively. The hydrophobicity of the SPI adhesive with CMC-Na was increased significantly; even moderate hydrophobic modification of the SPI adhesive with CMC-Na benefited the increase of its adhesive strength. SEM showed that particles on the surface of the SPI adhesive with addition of CMC-Na arrayed more uniformly and compact than the control, which was beneficial for its adhering to the bones. 【Conclusion】The addition of a trace amount of CMC-Na caused significant changes in the secondary structure of the SPI adhesive, the decline in α-helix content and an increase in β-sheet content, all of which indicated the unfolding of protein molecules and the aggregation of unfolding protein molecules. The increase in the hydrophobicity and zero shear viscosity of the SPI adhesive resulted in the significant increase of bond strength of low concentration SPI adhesive onto porcine bone. Since low concentration SPI might be easier to be absorbed by bodies than at a high concentration, our results after the addition of CMC-Na suggest that SPI adhesive has a great potential to be utilized as an adhesive in medical fields. Reference | Related Articles | Metrics Cited: Baidu(3)

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