The cryoprotective activity of tilapia skin collagen hydrolysate and the structure elucidation of its antifreeze peptide

Antifreeze peptides from fish byproducts have the potential to act as suitable and safe cryoprotectants, replacing synthetic additives currently utilized in the food industry. The main focus of this study was to explore the cryoprotective activity of antifreeze peptides from collagen hydrolysate of tilapia (Oreochromis niloticus) skin and deduce the relationship between its physio-chemical characteristics and antifreeze activity. Our results showed that the antifreeze peptides from tilapia skin collagen hydrolysate (TSCP) by alcalase had a lower molecular weight of <2500 Da, higher content of hydrophilic amino acids, and thermal hysteresis activity was 0.50 °C. TSCP33, the identified novel cryoprotectant peptide with a molecular weight of 454.26 Da, and the amino acid sequence -NHGK showed remarkable thermal hysteresis activity (THA) of 2.63 °C. Frozen scallop muscles treated with 3 g/100g TSCP exhibited higher salt soluble protein concentration, total sulfhydryl content, Ca2+-ATPase activity, and water-holding capacity during the 8 weeks storage period. The cryoprotective effect of 3 g/100g TSCP was equivalent to that of the commercial phosphorus antifreeze. Our findings provide a theoretical basis for developing safe peptide-based cryoprotectants which will maintain and improve the quality of frozen foods.