冻藏过程中南极磷虾蛋白理化特性和品质的变化

为了解冻藏南极磷虾理化性质和品质变化,本文测定了全虾和虾肉中不同蛋白组分含量变化,并采用二维电泳分析全虾样品的等电点和分子量分布,以水分含量、持水率、pH、硫代巴比妥酸反应物(TBARS)值为指标,进一步分析了蛋白品质的变化。结果表明:随冻藏时间的增加,南极磷虾全虾和虾肉盐溶性蛋白显著下降(p<0.05),碱溶性蛋白和非蛋白氮(NPN)显著上升(p<0.05)。二维电泳(2-DE)结果表明,盐溶性蛋白的蛋白点大多集中于pH4~6区域,水溶性和碱溶性蛋白在pH8~9也有分布;盐溶性蛋白的损失主要发生在肌球蛋白重链(210 kDa)和轻链(17~23 kDa)分子上;水溶性和碱溶性蛋白中蛋白点少量丢失。长期冻藏过程中,全虾和虾肉的含水量和持水率显著下降(p<0.05);全虾的pH和TBARS值明显升高(p<0.05),虾肉的pH和TBARS总体趋势略微上升(p>0.05)。各指标相关性分析表明,冻藏过程中虾品质指标的变化趋势具有一定的一致性。因此,随冻藏时间的增加,虾蛋白凝胶性质减弱,品质下降。

Physicochemical Properties and Quality Changes of Antarctic Krill during Frozen Storage Process

In order to realize the physicochemical properties and quality changes of antarctic krill during frozen storage,contents of different protein components in whole krill and krill meat protein sample were determined,and distribution of isoelectric point and molecular weight of protein in whole krill sample were analyzed by two-dimensional electrophoresis(2-DE). Then,changes of quality indexes,such as moisture content,water holding rate,pH and thiobarbituric acid reactive substances(TBARS)values were monitored during frozen storage. The results showed that salt-soluble protein decreased significantly(p<0.05),alkali-soluble protein and non-protein nitrogen(NPN)increased significantly in whole krill and krill meat while storage time lasting(p<0.05). The results of 2-DE showed that protein points of salt-soluble protein were mostly concentrated in the pH4~6,water-soluble protein and alkali-soluble protein points could also be found in pH8~9. The loss of salt-soluble proteins occurred mainly on the myosin heavy chain(210 kDa)and the light chain(17~23 kDa)molecules. The protein points of water-soluble protein and alkali-soluble protein were partially lost. During the frozen storage,the moisture content and water holding rate of whole krill and krill meat decreased significantly(p<0.05),and the pH and TBARS values of the whole krill increased significantly(p<0.05),pH and TBARS of krill meat increased slightly(p>0.05). Correlation analysis among various indexes showed that the change trend of krill quality indexes had certain consistency during frozen storage. In consequence,the gel properties and the quality of krill protein decreased with storage time increasing.