Abstract: Objective: To evaluate the cryoprotective effects of carrageenan oligosaccharides on peeled shrimp (Litopenaeus vannamei). Methods: The thawing loss, color, texture, myofibrillar protein content, Ca2+-ATPase activity, and microscopic structure of shrimp muscle were investigated during frozen storage with sodium pyrophosphate as a positive control. Results: Both sodium pyrophosphate and carrageenan oligosaccharide treatments significantly decreased the thawing loss, inhibited the degradation of myofibrillar proteins and Ca2+-ATPase activity, and maintained the pH and textural and color properties of shrimp muscle, when compared with the control during frozen storage. In addition, each treatment at a concentration of 3 g/100 mL showed better cryoprotective effect on shrimp muscle than at 1 g/100 mL. Importantly, carrageenan oligosaccharides were significantly more effective than sodium pyrophosphate (P < 0.05) at the same concentration of 3 g/100 mL. The microstructural analysis revealed that the texture of shrimps treated with 3 g/100 mL carrageenan oligosaccharide after six weeks of frozen storage was compact and showed good integrity, which was not significantly different from that of fresh shrimps after frozen storage. Conclusion: Carrageenan oligosaccharide treatment at 3 g/100 mL is more beneficial for maintaining the quality of white shrimp during frozen storage. This study can lay the foundation for developing a low-sweetness and low-calorie cryoprotective additive for frozen shrimp.

Key words: Litopenaeus vannamei, cryoprotective, water retention, sodium pyrophosphate, carrageenan oligosaccharides