中国农业科学 ›› 2023, Vol. 56 ›› Issue (12): 2380-2394.doi: 10.3864/j.issn.0578-1752.2023.12.012

• 食品科学与工程 • 上一篇    下一篇

黑曲霉改性葛渣膳食纤维的工艺优化及其理化功能特性

符慧珍1,2(), 邓梅2, 张名位2, 贾栩超2, 董丽红2, 黄菲2, 马勤2, 赵东2, 张瑞芬2()   

  1. 1 海南大学食品科学与工程学院,海口 570228
    2 广东省农业科学院蚕业与农产品加工研究所/农业农村部功能食品重点实验室/广东省农产品加工重点实验室,广州 510610
  • 收稿日期:2022-09-25 接受日期:2023-04-04 出版日期:2023-06-16 发布日期:2023-06-27
  • 通信作者: 张瑞芬,E-mail:ruifenzhang@163.com
  • 联系方式: 符慧珍,E-mail:fuhuizhen1104@163.com。
  • 基金资助:
    国家自然科学基金(31972082); 广东省特支计划本土创新团队项目(2019BT02N112); 科技创新战略专项资金(高水平农科院建设)(R2020PY-JG011); 科技创新战略专项资金(高水平农科院建设)(202108TD); 广州市重点研发计划(2023B03J1371)

The Optimal Fermentation Technique of Radix puerariae Residues by Aspergillus niger for Dietary Fiber Modification and the Consequent Changes of Physicochemical and Functional Properties of Dietary Fibers

FU HuiZhen1,2(), DENG Mei2, ZHANG MingWei2, JIA XuChao2, DONG LiHong2, HUANG Fei2, MA Qin2, ZHAO Dong2, ZHANG RuiFen2()   

  1. 1 College of Food Science and Engineering, Hainan University, Haikou 570228
    2 Sericultural & Agri-Food Research Institute, Guangdong Academy of Agricultural Sciences/Key Laboratory of Functional Foods, Ministry of Agriculture and Rural Affairs /Guangdong Key Laboratory of Agricultural Products Processing, Guangzhou 510610
  • Received:2022-09-25 Accepted:2023-04-04 Published:2023-06-16 Online:2023-06-27

摘要:

【目的】筛选适宜粉葛渣膳食纤维(dietary fiber,DF)改性的微生物种类,优化建立其最佳改性条件,分析改性前后葛渣DF结构和理化功能特性差异,为粉葛加工副产物的综合利用提供理论依据和技术支撑。【方法】比较黑曲霉、米根霉、绿色木霉和枯草芽孢杆菌发酵对葛渣可溶性DF(soluble dietary fiber,SDF)得率的影响,确定最佳发酵菌种;以料液比、接种量、发酵时间、发酵温度和pH为条件进行单因素试验,以SDF得率为考察指标,通过Box-Benhnken中心组合试验设计优化葛渣DF的最佳改性工艺条件;通过酶解法从发酵改性前后的葛渣中提取不溶性DF(insoluble dietary fiber,IDF)和SDF,利用扫描电镜观察其微观结构,对比分析葛渣发酵改性对其IDF理化(持水力、持油力和溶胀力)和功能特性(葡萄糖、胆酸盐和胆固醇吸附能力)的影响。【结果】黑曲霉、米根霉和绿色木霉发酵葛渣均能不同程度地增加葛渣中SDF得率,其中黑曲霉效果最好,而枯草芽孢杆菌发酵对葛渣中SDF得率无显著影响。因此,本研究选定黑曲霉为葛渣DF微生物改性菌种。通过响应面优化确定黑曲霉最佳发酵条件为料液比1﹕5.8(m/v)、接种量4.9%(v/v)、发酵时间100 h、发酵温度24.9 ℃,在该条件下SDF得率由发酵前的6.34%增加到13.75%,IDF/SDF的比例由6.14下降至2.83。与发酵前相比,黑曲霉发酵后葛渣IDF和SDF呈现更为疏松多孔的微观结构。发酵后葛渣IDF的持水力和溶胀力均是发酵前的1.2倍,但持油力无显著变化。此外,发酵后葛渣IDF的葡萄糖吸附能力是发酵前的1.70倍,胆固醇吸附能力在pH 2.0和pH 7.0条件下分别是发酵前的1.44倍和1.28倍。【结论】4种受试菌株中,黑曲霉促进葛渣IDF转化为SDF的作用最显著,以SDF得率为指标优化建立了黑曲霉发酵改性葛渣DF的最佳工艺;发酵后葛渣SDF得率提高2.17倍,IDF的理化和功能特性均得到改善。

关键词: 葛渣, 黑曲霉, 不溶性膳食纤维, 可溶性膳食纤维, 理化功能特性

Abstract:

【Objective】 The objectives of the present study were to screen the microbial species suitable for modification of dietary fiber (DF) of Radix puerariae residues, to establish the optimum fermentation conditions, and to clarify the changes of microstructure, physicochemical and functional properties of Radix puerariae residues DF before and after fermentation modification.【Method】Aspergillus niger, Rhizopus oryzae, Trichoderma viride and Bacillus subtilis subsp were used to ferment Radix puerariae residues, respectively, and the most effective microbial strain was screened by comparing the SDF yield of Radix puerariae residues. The single factor experiments were carried out to screen the factors influencing DF modification. Then, the Box-Benhnken central composite experiment was designed to establish the optimum DF modification conditions of Radix puerariae residues with the SDF yield as the index of evaluation. The insoluble DF (IDF) and SDF of Radix puerariae residues before and after modification under optimal fermentation conditions were extracted by enzymatic hydrolysis method. The microstructures of IDF and SDF were observed by scanning electron microscope, and the physicochemical (water holding, oil holding, and water swelling capacity) and functional properties (adsorption capacity of glucose, sodium cholate and cholesterol) of IDF samples from unfermented and fermented Radix puerariae residues were analyzed.【Result】The fermentation of Radix puerariae residues, by A. niger, R. oryzae or T. viride all increased the SDF yield, and A. niger was the most effective species. However, the fermentation with B. subtilis subsp had no significant effects on the SDF yield. Therefore, A. niger was selected as the most suitable strain for Radix puerariae residues fermentation. The optimal fermentation condition determined by response surface optimization was as follows: The ratio of solid-liquid was 1:5.8 (m/v), the inoculation volume was 4.9% (v/v), the fermentation time was 100 h, and the fermentation temperature was 24.9 ℃. Under this condition, the yield of SDF increased from 6.34% to 13.75%, while the ratio of IDF/SDF decreased from 6.14 to 2.83. Both IDF and SDF extracted from fermented Radix puerariae residues by A. niger showed more porous microstructure than those from unfermented Radix puerariae residues. Fermentation of Radix puerariae residues increased the water holding and swelling capacity of its IDF by 20 percent approximately, while it showed no significant effects on the oil holding capacity. In addition, after fermentation, the adsorption capacity of IDF of Radix puerariae residues for glucose increased by 70%, and the adsorption capacity for cholesterol increased by 44% and 28% at pH 2.0 and pH 7.0, respectively. 【Conclusion】 A. niger could modify DF of Radix puerariae residues more effectively than other 3 microbial strains. Under the fermentation condition, the SDF yield of Radix puerariae residues increased by 2.17 times after modification by A. niger, and the physicochemical and functional properties of its IDF were also improved significantly.

Key words: Radix puerariae residues, Aspergillus niger, insoluble dietary fiber, soluble dietary fiber, physicochemical and functional properties