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.