蛋白质磷酸化修饰对宰后肉品质有重要影响。三磷酸腺苷（ATP）是一种能量来源并且在蛋白激酶存在的条件下可将磷酸基团转移到蛋白质上发生磷酸化反应。但是在宰后肉中，ATP含量如何影响蛋白质磷酸化研究较少。本研究旨在探究ATP对羊肉糜中蛋白质磷酸化及蛋白降解的影响。通过向羊肉糜中添加/不添加ATP作为处理组和对照组，并贮藏在25°C和4°C条件下。ATP处理组和对照组中的pH变化不一致，且两个温度下ATP处理组中的肌原纤维蛋白磷酸化水平显著高于对照组中的肌原纤维蛋白磷酸化水平（P<0.05），表明ATP对宰后肉中蛋白质磷酸化水平起重要作用。ATP处理组中的μ-钙蛋白酶、肌间线蛋白和肌钙蛋白T降解慢于处理组中的μ-钙蛋白酶、肌间线蛋白和肌钙蛋白T降解，表明ATP与蛋白降解负相关。本研究阐明了ATP通过调控肌原纤维蛋白磷酸化及蛋白降解而影响肉品质的重要作用。

Ovine bones are the major by-products after slaughtered.  The present study was conducted to extract and characterize acid soluble collagens (ASC) and pepsin soluble collagens (PSC) from ovine bones (Ujumuqin sheep).  Ovine bones collagen were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) as type I collagen.  The results of Fourier transform infrared (FTIR) spectra analysis testified the existence of triple superhelical structure in both ASC and PSC, showing pepsin did not disrupt the triple helical structure of ovine bones collagen.  Glycine, accounting for one-third of total amino acids, was the major amino acid for ovine bones collagen.  Higher imino acid content was responsible for higher thermal denaturation temperature of ovine bones collagen compared to fish collagens.  The isoelectric point of ASC was lower than PSC due to the higher content of acidic amino acids.  Therefore, this study provides the potential reference for collagen extraction and application of ovine bones by-procduct.

This study investigated the influence of activities of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and lactate dehydrogenase-B (LDH-B) on the colour stability of mutton.  From 60 sheep (Bayannur mutton sheep), 15 longissimus dorsi (LD) muscles were selected on the basis of colour stability (R630/580 and a* value) during the storage and classified into three groups (5 for each group) as high colour stability (HCS), intermediate colour stability (ICS) and low colour stability (LCS).  The activities of GAPDH and LDH-B, muscle colour attributes, nicotinamide adenine dinucleuotide (NADH) concentration and lactate concentration were measured.  The samples in HCS had higher activities of GAPDH and LDH-B than the samples in the LCS, and the samples in the HCS group also possessed higher NADH and lower lactate concentration.  The higher activity of dehydrogenase enzyme may result in higher NADH concentrations and colour stability in muscle tissue.  The results suggest that the activity of GAPDH and LDH-B may also play a role in maintaining colour stability.

Fatty acid composition of neutral lipids (NLs), phospholipids (PLs) and free fatty acids (FFAs) from intramuscular fat (IMF), lipid oxidation and lipase activity in muscle Semimembranosus (SM) and msucle Biceps femoris (BF) of dry-cured Xuanwei ham during the 90-d salting stages were analysed. The salt content increased from 0.34 to 3.52% in BF and from 0.10 to 5.42% in SM during the 90 d salting stage, respectively. PLs of IMF in both BF and SM decreased 54.70% (P<0.001) and 34.64% (P<0.05), furthermore, the saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) of PLs in both muscles were hydrolysed almost isochronously. FFAs were increased from 0.46 g 100 g-1 lipids to 2.92 g 100 g-1 lipids in BF at the end of salting, which was lower than SM (from 1.29 g 100 g-1 lipids to 9.70 g 100 g-1 lipids). The activities of acid lipase, neutral lipase and acid phospholipase all remained active in the 90 d. The thiobarbituric acid reactive substances (TBARS) was slowly increased to 1.34 mg kg-1 muscle in BF and to 2.44 mg kg-1 muscle in SM during the salting stage. In conclusion, the controlled salting process prompted the hydrolysis of PLs of IMF notably and increased the lipid oxidation of muscles within some limits.