Chitooligosaccharide-gallic acid complexes suppress the denaturation of myofibrillar proteins in peeled shrimp (Litopenaeus vannamei) during frozen storage

The cryoprotective effects of chitooligosaccharide-gallic acid (COS-GA) complexes on peeled Pacific white shrimp were investigated and compared with single treatments of COS, GA and polyphosphate (PP) during 49 days of frozen storage at -5 degree celsius. The data revealed a significant improvement in the antioxidant activity of COS through the conjugation of COS and GA. The soaking treatments of COS-GA and PP effectively maintained the water-holding capacity and sensory properties of shrimp muscle compared with the water-soaked shrimp (control). Furthermore, the COS-GA-soaked shrimp samples exhibited significant inhibitory effects on the textural and chrominance deterioration of muscle tissues compared with the control samples. Chemical analyses demonstrated that the COS-GA treatment also preserved higher levels of myofibrillar protein content, total sulfhydryl content and Ca2+-ATPase activity in the frozen shrimp samples. Histological observations indicated that the COS-GA soaking treatment effectively protected the integrity and stability of muscle tissues. Overall, COS-GA exhibited superior antioxidation and water-retaining properties, stabilising the shrimp muscle during long-term frozen storage.