Effect of cryogenic liquid quick-freezing on the biochemical properties of soft shell swimming crab ( Portunus trituberculatus) muscle during frozen storage

In order to confirm the effect of cryogenic liquid quick- freezing on preservation of soft shell swimming crab.The changes of biochemical properties of soft shell swimming crab muscle during the frozen storage period of 90 days at-20℃ with liquid quick-freezing under-25、-35 and-50℃ were studied by measuring the solubility of actomyosin, - SH content, Ca2 +- ATPase activities, WHC, pH value and TBA value.The result indicated that: the solubility of actomyosin, -SH content and Ca2 +-ATPase activities decreased with prolonging of the frozen storage period from the treatment groups; pH decreased first and then increased; TBA value ascended persistently; in the first 60 days of the frozen storage period, the solubility of actomyosin and Ca2 +- ATPase had no significant difference ( p > 0.05) and appeared significant difference later ( p < 0.05) among the three treatment groups.- SH content declined rapidly and emerged significant difference ( p < 0.05) between the different treatment groups after30 days.At the same time, the group at-25℃ was lower significantly than the group at-50℃ ( p < 0.01) .Therefore, the temperature of liquid quick-freezing is lower, the slower deteriorated in soft shell swimming crab muscle.