Kappa‐carrageenan and xylooligosaccharide effect on water mobility and structural changes in silver carp proteins during frozen storage

Abstract BACKGROUND The cryoprotective effect of xylooligosaccharide (XO) and kappa‐carrageenan (KC) mixture on silver carp proteins in fluctuated frozen storage from 4 to −18 °C was analyzed. Positive control as a conventional cryoprotectant mixture of sucrose (4%) and sorbitol (4%), KC (3%) and XO/KC (3%) treatments were incorporated in silver carp surimi and myofibrillar proteins to analyze the water mobility and its influence on structural attributes. RESULTS The temperature fluctuation significantly increased the structural alteration in samples with no treatments due to oxidative changes, protein denaturation and recrystallization. Meanwhile, the mixture of XO and KC (XO/KC 3%) significantly reduced the tertiary and secondary structural alterations by preventing the oxidative changes in α ‐helix and tryptophan (Trp) residues. Moreover, XO/KC (3%) inhibited water mobility, hindering the T 22 relaxation time, as compared to the samples added with KC (3%) and the positive control. Interestingly, the XO/KC (3%) mixture significantly reduced the formation of extracellular spaces and recrystallization by restricting the partial dehydration of muscles and extracellular solution concentration. CONCLUSION From the current results, it can be concluded that the XO/KC mixture could be efficient in protecting aquatic food proteins during fluctuating frozen storage by preventing the exposure of Trp residues and α ‐helix contents. Moreover, XO/KC restricted the water mobility by establishing a bond and making water unavailable for crystallization and recrystallization. Therefore, XO/KC could be used as an effective mixture to prevent fluctuated and frozen storage changes in aquatic foods. © 2024 Society of Chemical Industry.