干腌牛肉加工过程中蛋白质变化对品质的影响

The effect of protein changes on the quality of dry-cured beef during processing

以原料期、腌制期、风干期、发酵中期、发酵后期、成熟期的干腌牛肉为研究对象,对产品色泽、质构、游离氨基酸含量及蛋白质变化进行测定,以期明确干腌牛肉加工过程中蛋白质氧化、降解及结构变化对产品品质的影响。结果表明:干腌牛肉色泽呈暗红,硬度、胶着性、咀嚼性、黏性和回复性呈显著增加(P<0.05)趋势;加工过程中肌浆蛋白和肌原纤维蛋白羰基含量显著增加(P<0.05)、巯基含量显著下降(P<0.05),与原料期相比,成熟期的羰基含量分别增加了53.51%、36.83%,巯基含量减少了40.70%、49.27%;SDS-PAGE凝胶电泳图谱显示蛋白质在加工过程中均发生显著降解;拉曼光谱分析表明,蛋白质结构由有序向无序变化。加工过程中游离氨基酸总含量整体呈显著上升趋势(P<0.05),以谷氨酸、赖氨酸和天冬氨酸增长最显著(P<0.05),分别增长了51.38%、42.77%、42.47%;相关性分析显示,干腌牛肉色泽与咀嚼性、黏性、羰基、巯基、α-螺旋、β-转角具有显著相关性,蛋白质氧化、降解使蛋白质结构发生变化,进而影响产品的食用品质。综上所述,干腌牛肉加工过程中蛋白质生化变化对产品品质有促进作用。

In order to study the effect of protein oxidation,degradation and structural changes on the product quality,dry-cured beef in the raw material period,curing period,air-drying period,middle fermentation period,late fermentation period,and mature period were used as the raw materials to determine color,texture,free amino acid content and protein changes.The results showed that the color of dry-cured beef was dull-red,and the hardness,gumminess,chewiness,adhesiveness and resilience were significantly increased(P<0.05).Moreover,the myosin and myofibrillar proteins protein carbonyl content increased notably(P<0.05),and sulfhydryl content decreased significantly(P<0.05).In addition,after the mature period,the contents of carbonyl groups increased by 53.51%and 36.83%,respectively,meanwhile the total sulfhydryl content decreased by 40.71%and 49.27%compared with raw material.Furthermore,the sodium dodecyl sulfate-polyacrylamide gel electrophoresis(SDS-PAGE)showed that the proteins were prominently degraded.Besides,raman spectroscopy showed that the protein structure changed from order to disorder.The total content of free amino acids significantly increased as a whole(P<0.05),particularly,the glutamic acid,lysine acid and aspartic increasing most significantly(P<0.05),which increased by 51.38%,42.77%,and 42.47%,respectively.Correlation analysis shows that the color of dry-cured beef were significantly correlated with the index of chewiness,adhesiveness,carbonyl,sulfhydryl,α-helix,andβ-turn.Protein structure changed due to its oxidation and degradation,which affected the eating quality of the product.In conclusion,the protein biochemical changes had a positive effect on the product quality during the processing of dry-cured beef.