Li K, Zhao Y Y, Kang Z L, Wang P, Han M Y, Xu X L, Zhou G H
Key Laboratory of Meat Processing and Quality Control, Ministry of Education, Key Laboratory of Animal Products Processing, Ministry of Agriculture, Synergetic Innovation Center of Food Safety and Nutrition, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, PR China.
Key Laboratory of Meat Processing and Quality Control, Ministry of Education, Key Laboratory of Animal Products Processing, Ministry of Agriculture, Synergetic Innovation Center of Food Safety and Nutrition, College of Food Science and Technology, Nanjing Agricultural University, Nanjing, 210095, PR China
Poult Sci. 2015 Jan;94(1):111-22. doi: 10.3382/ps/peu040.
The objectives of this study were to evaluate protein thermal stability, water-protein interaction, microstructure, and protein conformation between PSE-like and normal chicken breast meat batters. Sixty pale, soft, and exudative (PSE)-like (L*>53, pH24 h<5.7) and 60 normal (46<L*<53, 5.7<pH24 h<6.1) chicken breast meats were selected from 3 different occasions in a major Chinese commercial plant. Two different meat batters were formulated to 14% meat protein and 2% salt, and they were analyzed for the protein changes and the microstructure using differential scanning calorimetry, low-field (LF)-NMR, SEM, and Raman spectroscopy. PSE-like meat batter had lower gel strength, water-holding capacity, and salt-soluble protein extraction (P<0.05). Heated PSE-like meat batter formed an aggregated gel matrix, while normal meat batter produced a compact gel network with fine, cross-linked strands by many protein filaments. LF-NMR revealed an increase in the water mobility in heated PSE-like meat batter with an increasing amount of loosely bound water (P<0.05). No significant changes were observed in the electrophoretic patterns of salt-soluble protein extracts by SDS-PAGE. However, differential scanning calorimetry showed that PSE-like meat had greater myosin and sarcoplasmic proteins/collagen denaturation (P<0.05). In PSE-like meat, actin denaturation was particular evident after salt addition (P<0.05) using differential scanning calorimetry. Moreover, Raman spectroscopy indicated that PSE-like meat batter had less unfolded α-helix and β-sheet structure formation, reduced exposure of hydrophobic and tyrosine residues (P<0.05), and changes in the microenvironment of aliphatic residues and tryptophan, which affected salt-soluble protein extraction, gel properties, and water-holding capacity. In conclusion, the inferior functional properties of PSE-like meat were attributed to not only myosin denaturation, but also actin denaturation after salt addition and different protein structural states.
本研究的目的是评估类PSE鸡胸肉和正常鸡胸肉面糊之间的蛋白质热稳定性、水-蛋白质相互作用、微观结构和蛋白质构象。从中国一家大型商业工厂的3个不同批次中挑选出60块类苍白、柔软、渗水（PSE）（L*>53，pH24 h<5.7）和60块正常（46<L*<53，5.7<pH24 h<6.1）的鸡胸肉。将两种不同的肉面糊配方制成含14%肉蛋白和2%盐的产品，并使用差示扫描量热法、低场（LF）-核磁共振、扫描电子显微镜和拉曼光谱分析其蛋白质变化和微观结构。类PSE肉面糊的凝胶强度、持水能力和盐溶性蛋白提取率较低（P<0.05）。加热后的类PSE肉面糊形成聚集的凝胶基质，而正常肉面糊则通过许多蛋白质细丝产生具有精细交联链的致密凝胶网络。LF-核磁共振显示，加热后的类PSE肉面糊中水的流动性增加，松散结合水的量增加（P<0.05）。通过SDS-PAGE对盐溶性蛋白提取物的电泳图谱未观察到显著变化。然而，差示扫描量热法表明，类PSE肉的肌球蛋白和肌浆蛋白/胶原蛋白变性程度更高（P<0.05）。在类PSE肉中，使用差示扫描量热法发现加盐后肌动蛋白变性尤为明显（P<0.05）。此外，拉曼光谱表明，类PSE肉面糊中未折叠的α-螺旋和β-片层结构形成较少，疏水和酪氨酸残基的暴露减少（P<0.05），脂肪族残基和色氨酸的微环境发生变化，这影响了盐溶性蛋白提取、凝胶特性和持水能力。总之，类PSE肉较差的功能特性不仅归因于肌球蛋白变性，还归因于加盐后肌动蛋白变性以及不同的蛋白质结构状态。
