Effects of trehalose antifreeze agent on quality of Litopenaeus vannamei during frozen storage

The effects of trehalose on peeled shrimp(Litopenaeus vannamei)during frozen storage was investigated by monitoring thawing loss,color,myofibrillar protein content,Ca²⁺-ATPase activity and performing microscopic structural analysis.0.5% and 1.0%(w/v)trehalose,sodium alginate and alginate oligosaccharide solutions were used as antifreeze water retention agent,distilled water and 0.5% and 1.0%(w/v)sodium pyrophosphate were negative control group and positive control group,respectively,and stored at-18 ℃ for 6 weeks.The results showed that trehalose,alginate oligosaccharide and sodium pyrophosphate had significant inhibitory effect on the thawing loss of shrimp(p<0.05)compared with the control group.L^* values revealed that these saccharides had a positive effect on color stability during frozen storage. In addition,the results of chemical analyses showed that trehalose and alginate oligosaccharide treatments effectively maintained an increased myofibrillar protein content and Ca²⁺-ATPase activity in frozen shrimp. The content of myofibril reached 104.2 and 103.2 mg/g,and Ca²⁺-ATPase activity reached 0.141 μmol Pi/mg·min and 0.142 μmol Pi/mg·min,respectively.In addition,hematoxylin and eosin staining and SDS-PAGE confirmed that these cryoprotective saccharides slowed the degradation of muscle proteins and the damage to muscle tissue structures.The muscle fibers of shrimp muscle were intact,and there was no large gap between the muscles. The tissue integrity of the frozen shrimp was better maintained,and the strength of the myosin and actin bands were not significantly reduced.The results of comprehensive study showed that trehalose and alginate oligosaccharide antifreeze had good antifreeze effect during the freezing process of Litopenaeus vannamei,which could better guarantee the quality and quality of frozen shrimp and gained as a better alternative to the phosphatepreserving agent of frozen aquatic products.