Kappa-carrageenan and its oligosaccharides maintain the physicochemical properties of myofibrillar proteins in shrimp mud (Xia-Hua) during frozen storage

As a popular hot-pot ingredient, Chinese-style shrimp mud (Xia-Hua) is usually transported and stored frozen. However, frozen storage leads to decreased quality of Xia-Hua products caused by the variations in physicochemical and functional properties of myofibrillar proteins (MPs). Kappa-carrageenan and its oligosaccharides are reported as antioxidants and antifreeze and can stabilize proteins in whole shrimp, but their effects on MPs in Xia-Hua remain poorly understood. Compared to the control and Na4P2O7 treatments, the physicochemical properties of MPs in kappa-carrageenan and its oligosaccharides-incorporated Xia-Hua were evaluated during 120 days of frozen storage. The results showed that cold stress increased the susceptibility of MPs to denaturation and oxidation during frozen storage. Carrageenan oligosaccharides maintained the turbidity, emulsifying activity, stability, and foaming capacity of MPs. Oxidation analysis showed that the incorporation of carrageenan oligosaccharides significantly retarded the rapid decrease of Ca2+-ATPase activity, total sulphydryl and active sulphydryl contents, and also effectively inhibited the increases of carbonyl content and surface hydrophobicity of MPs. Thermal stability results confirmed that the oligosaccharides improved the denaturation temperature and enthalpy of MPs compared to the control, Na4P2O7, and carrageenan treatments. This study suggests that kappa-carrageenan and its oligosaccharides maintain the properties of MPs in Xia-Hua during frozen storage. Practical Application The cryoprotection and antioxidant effects of carrageenan oligosaccharides on the stability of MPs in frozen shrimp mud can be used to extend the shelf-life and maintain the quality of frozen Xia-Hua products. Furthermore, it can drive the development of aquatic product health industry, improve the quality and safety of aquatic products, reduce the occurrence of public food safety incidents, and maintain social stability.