大黄鱼冷藏过程肌肉蛋白质生化特性与新鲜度的相关性

为研究大黄鱼冷藏期间肌肉蛋白质变化与鲜度品质的相关性，以色差值、质构、挥发性盐基氮(TVB-N)以及感官评分等鲜度指标判断鱼肉品质，并结合肌肉蛋白质中盐溶性和水溶性蛋白质含量、总巯基含量、羰基含量、蛋白质分子量以及粒径分布等蛋白质生化特性指标，分析大黄鱼4 ℃冷藏10天肌肉蛋白质变化与鲜度品质的相关性。结果表明：冷藏期间大黄鱼鱼肉的L*，a*和w值下降，b*值上升；鱼肉咀嚼性、黏着性和硬度下降；TVB-N由(4.42±0.21)mg/100 g增至(38.46±0.87)mg/100 g，并于第8天达二级鲜度标准，感官评分第8天不可接受。冷藏期间大黄鱼盐溶性和水溶性蛋白质含量、总巯基含量、羰基含量变化趋势相似。盐溶性蛋白质含量呈先小幅上升后下降变化趋势，由(159.36±6.51)mg/g降至(91.99±13.82)mg/g，质量分数下降了42.27%，水溶性蛋白质含量由(33.68±2.13)mg/g降至(17.57±0.70)mg/g，质量分数下降了47.77%；盐溶性蛋白质的巯基含量和羰基含量分别由(3.95±0.04)mol/105 g pro降至(1.08±0.13)mol/105 g pro、(1.08±0.04)nmol/mg升至(3.94±0.43)nmol/mg，水溶性蛋白质巯基含量和羰基含量分别由(4.74±0.17)mol/105 g pro降至(2.66±0.15)mol/105 g pro、(0.21±0.14)nmol/mg升至(2.67±0.25)nmol/mg；盐溶性蛋白质粒径在冷藏第0～8天，由(203.32±5.44)nm增大至(425.40±8.63)nm，8天后降至(317.03±1.20)nm，水溶性蛋白质粒径从(190.80±0.30)nm降至(144.23±1.32)nm；SDS-PAGE电泳证明30 ku左右产生新的蛋白质条带且蛋白质量有一定程度减少。结果表明盐溶性和水溶性蛋白质生化特性与新鲜度有良好相关性，其中水溶性蛋白质相关性更好。

Correlation between changes in freshness and biochemical characteristics of Larimichthys crocea muscle protein during cold storage

In order to study the correlation between Pseudosciaena crocea muscle protein and freshness quality during cold storage, the quality was judged by freshness indicators such as color, TPA, TVB-N and sensory, water-soluble protein and salt-soluble protein were extracted from Pseudosciaena crocea muscle and biochemical characteristics were analyzed during storage , including protein content ,total sulfhydryl groups, carbonyl content, protein molecular weight and particle size distribution. The correlation between changes in freshness and biochemical characteristics of Pseudosciaena crocea muscle protein was analyzed. The L*, a* and w values of Pseudosciaena crocea fish meat decreased, while the b* value increased; the chewiness, stickiness and hardness of Pseudosciaena crocea decreased obviously; TVB-N increased from (4.42±0.21)mg/100 g to (38.46±0.87)mg/100 g, and approached the secondary freshness standard at 8 days, but the sensory evaluation score was not accepted at the 8th day. During storage, the content of salt-soluble protein, water-soluble protein, total sulfhydryl content, and carbonyl content of Pseudosciaena crocea had similar changes. The content of salt-soluble protein increased slightly in the early stage and decreased in the late stage, from (159.36±6.51)mg/g to (91.99±13.82)mg/g. The mass fraction decreased by 42.27%. The content of water-soluble protein decreased from (33.68±2.13)mg/g to (17.57±0.70)mg/g, and the mass fraction decreased by 47.77%.The contents of sulfhydryl group and carbonyl group of salt-soluble protein increased from (3.95±0.04)mol/105g pro to (1.08±0.13)mol/105g pro and from (1.08±0.04)nmol/mg to (3.94±0.43)nmol/mg, respectively. The sulfhydryl and carbonyl contents of water-soluble protein changed from (4.74±0.17)mol/105g pro to (2.66±0.15)mol/105g pro and (0.21±0.14)nmol/mg to (2.67±0.25)nmol/mg, respectively. The particle size of salt-soluble protein increased from (203.32±5.44)nm to (425.40±8.63)nm during 0-2 days of cold storage, and decreased to (317.03±1.20)nm after 2 days. The particle size of water-soluble protein decreased from (190.80±0.30)nm to (144.23±1.32)nm. In the SDS-PAGE electrophoresis, there was a new protein band produced at about 30 ku, and the amount of protein was reduced. The results showed that the biochemical properties of water-soluble protein and salt-soluble protein have a good correlation with freshness, and water-soluble protein has better correlation.