Abstract:The aim of this study was to explore the cryoprotective effects of different saccharides on whiteleg shrimp (Litopenaeus vannamei) muscle during frozen storage with temperature fluctuations. The effects of xylooligosaccharide, carrageenan oligosaccharide, trehalose, and algae oligosaccharide on quality characteristics of shrimp muscle were evaluated upon exposure to temperature fluctuations between -55 ℃ and -24 ℃, with sodium pyrophosphate and distilled water treatments as the positive and negative controls, respectively. The results showed that xylooligosaccharide, carrageenan oligosaccharide, trehalose, and alginic oligosaccharide significantly reduced the thawing loss of frozen shrimp, compared with the distilled water treated group (the lowest value was 8.58% in carrageenan oligosaccharide group) during 144 days of frozen storage with temperature fluctuations. These saccharides effectively maintained the texture properties of shrimp muscle, the optimum elasticity and chewiness were 1.42 mm and 6.80 mJ, respectively. Meanwhile, these saccharides soaking treatments also slowed the degradation of myofibrillar proteins (106.10 mg/g~111.67 mg/g), decreased Ca2+-ATPase activity (0.124 U/mg~0.136 U/mg) and total sulfhydryl content (7.6 mmol/L~8.1 mmol/L) in the shrimp muscle. Microstructure results showed that compared with distilled water group, the muscle connective structure of shrimp tissues treated with saccharides was more complete, the gap among muscle bundles was smaller, and there was no large area of distortion and rupture observed, which showed good maintenance effects on the microstructure of frozen shrimp tissues. These results suggest that the xylooligosaccharides, carrageenan oligosaccharides, trehalose, and alginate oligosaccharides can be developed and utilized as the antifreeze and water-retaining agents for frozen shrimps.
