The cryoprotectant effect of xylooligosaccharides on denaturation of peeled shrimp (Litopenaeus vannamei) protein during frozen storage

The cryoprotective effects of xylooligosaccharides on peeled whiteleg shrimp were investigated and compared with sodium pyrophosphate treatment during frozen storage, primarily the interaction mechanisms between xylooligosaccharides and shrimp myosin. Data revealed that soaking in the xylooligosaccharides solutions prior to frozen storage markedly reduced thawing and cooking losses in frozen shrimp, which were significantly lower than that of fresh water treatment. The significant inhibitory effects on textural variables (springiness and chewiness) in oligosaccharides-treated shrimp were also found, compared to the control samples. Chemical analyses showed that these oligosaccharides maintained a higher myofibrillar protein content and Ca2+-ATPase activity in frozen shrimp. Additionally, the hematoxylin and eosin staining results indicated that the oligosaccharides significantly slowed the damage to muscle tissue structures. Our assumption was that water replacement hypothesis played a leading role in cryoprotection of frozen shrimp in this study, as shown in previous experimental results and reports. Furthermore, the homology modeling and molecular dynamics simulations confirmed that the oligosaccharides substituted water molecules around shrimp myosin surface by forming hydrogen bonds with polar residues of amino acids, thereby stabilizing the structures in the absence of water, leading to an increase in protein stability during frozen storage. Overall, the contribution of the water-replacement activities played an important role in cryoprotective effects of this oligosaccharides on frozen shrimp. Further application of these findings might maintain better quality and extend the commercialization of refrigerated shrimp products. (C) 2017 Elsevier Ltd. All rights reserved.