Insights into Cryoprotective Roles of Carrageenan Oligosaccharides in Peeled Whiteleg Shrimp (Litopenaeus vannamei) during Frozen Storage

The cryoprotective effects of carrageenan oligosaccharides on peeled whiteleg shrimp were investigated and compared with sodium pyrophosphate treatment during frozen storage, primarily the interaction mechanisms between oligosaccharides and shrimp myosin. Data revealed significant profitable effects on water-holding capacity and textural variables in oligosaccharide-treated shrimp compared to the control. Chemical analyses showed that these saccharides maintained a higher myofibrillar protein content and Ca²⁺-ATPase activity in frozen shrimp. Additionally, the hematoxylin and eosin staining results indicated that the saccharides significantly slowed the damage to muscle tissue structures. The assumption was that water replacement hypothesis played a leading role in cryoprotection of frozen shrimp. Furthermore, the homology modeling and molecular dynamics simulations confirmed that the saccharides substituted water molecules around the 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.