Trash to treasure: Potential antifreeze peptide from Litopenaeus vannamei head via ultrasound-assisted autolysis

This study aimed to separate and purify antifreeze peptides (AFP) from the autolysate of Litopenaeus vannamei head, and the peptide sequences with antifreeze activity were identified to elucidate the potential antifreeze mechanisms. The initial fractionation of autolysate revealed that the pk1 fraction with less than 3 kDa molecular weight exhibited the highest thermal hysteresis activity (2.28 °C). Notably, the component pk1-A with the strongest antifreeze activity (2.80 °C) was further separated by using a Sephadex G-15 gel filtration column. The results of bioinformatics and computer-assisted techniques indicated that 26 types of peptides from pk1-A were identified as AFP. Among these, KQVHPDTGISSK was selected as a potential Litopenaeus vannamei head antifreeze peptide (LvAFP). The active site (Lys residue) of LvAFP was discovered to strongly interact with water molecules via hydrogen bonding, thereby inhibiting the formation and recrystallization of ice crystals. Therefore, the preparation of LvAFP could improve the high-value utilization of shrimp byproducts.