冷藏大菱鲆新鲜度评价辅助蛋白指标和指示物

Studies on the Auxiliary Evaluation Indexes and Indicators of Freshness for Refrigerated Turbot(Scophthalmus maximus)

以大菱鲆为对象,通过测定4℃冷藏过程中肌原纤维蛋白盐溶性、Ca2+-ATPase、总巯基含量、表面疏水性、TCA可溶性肽含量、SDS-PAGE,以及TVB-N值和菌落总数等指标,考察冷藏过程中大菱鲆肌肉蛋白质的变化,并分析其与新鲜度指标的相关性,筛选评价新鲜度的辅助蛋白指标及指示物。结果显示:随着贮藏时间的延长,大菱鲆肌原纤维蛋白盐溶性、Ca2+-ATPase活性均显著下降(P<0.05),表面疏水性、TCA可溶肽含量显著上升(P<0.05);总巯基含量呈先上升后下降趋势。SDS-PAGE电泳显示总蛋白中的条带I(25~26 ku),低盐溶蛋白中的条带III(41 ku)、条带IV(38~39 ku),高盐溶蛋白中的肌球蛋白重链、原肌球蛋白、条带II(37 ku)等的光密度值发生规律性升高或降低。TVB-N值、菌落总数均随贮藏时间的延长显著增加,贮藏15 d达到货架期终点。相关性分析表明:肌原纤维蛋白的盐溶性、表面疏水性、Ca2+-ATPase活性、TCA可溶性肽与菌落总数、TVBN值均具显著相关性,可作为4℃冷藏大菱鲆新鲜度评价的辅助蛋白指标;低盐溶性蛋白中的条带III、条带IV,高盐溶性蛋白中的肌球蛋白重链、原肌球蛋白以及条带II,总蛋白中的条带I均与菌落总数、TVB-N值有显著的相关性,均有望作为冷藏大菱鲆的新鲜度指示物。

The changes of salt solubility of myofibrillar protein, Ca^2＋-ATPase, total sulphur content, surface hydrophobicity, TCA-soluble peptides, SDS-PAGE gel electrophoresis, and TVB-N, total viable counts（TVC） of turbot stored at4 ℃ were studied, aimed to investigate the correlation between the changes of muscle proteins and freshness indexes during storage, and to screen out auxiliary indexes of freshness or freshness indicators. The results showed that the salt solubility of myofibrillar protein Ca^2＋-ATPase decreased significantly（P〈0.05）, while surface hydrophobicity and TCA soluble peptides content increased significantly（P〈0.05）. The total sulphur content increased at the beginning of storage then decreased with time extended. SDS-PAGE electrophoresis showed that 25-26 ku band in total protein, 38-39 ku band and41 ku band in low salt soluble protein and MHC, tropomyosin, 37 ku band in high salt soluble protein, etc, had regularly changes regularly. TVB-N and TVC increased gradually during storage, which indicating a shelf life 15 days for turbot stored at 4 ℃. Correlation analysis showed that the salt solubility of myofibrillar protein, Ca^2＋-ATPase, surface hydrophobicity and TCA-soluble peptides were markedly correlated with TVB-N and TVC, and can be used as auxiliary freshness indexes of refrigerated turbot. Meanwhile, band III and band IV in low salt soluble protein, band I in total protein and MHC, tropomyosin, band II in high salt soluble protein are also obviously correlated with TVB-N and TVC,thus they could be used as freshness indicators of turbot.