The cryoprotective effect of Litopenaeus vannamei head-derived peptides and its ice-binding mechanism

Although discarded as waste, shrimp heads are a potential source of antifreeze peptides, which can be used as cryoprotectants in the food industry. Their utilization in frozen foods can help mitigate the negative effects caused by the freezing technique. Litopenaeus vannamei s hrimp heads were autolyzed, and the shrimp head autolysate (SHA) was separated via ultra-filtration and ion exchange chromatography. The antifreeze effect of SHA on the biochemical properties of myofibrillar proteins of peeled shrimps during five freeze-thaw cycles was evaluated. Peptide screening was done using the LC-MS/MS technique. A molecular docking (MD) study of the interaction between ice and shrimp head-derived antifreeze peptides was done. Results showed that shrimp-head autolysate has a maximum thermal hysteresis value of 1.84 degrees C. During the freeze-thaw cycles, the shrimp-head autolysate exhibited an antifreeze effect on frozen peeled shrimps. 1.0 and 3.0%-SHA groups showed significantly lower freeze denaturation than the negative control group. The muscle tissues of SHA-treated groups were not as severely damaged as the negative control group. The molecular docking study revealed that the shrimp head-AFPs bound to ice via hydrogen bonding, and both hydrophilic and hydrophobic amino acid residues were involved in the ice-binding interactions. 6 ice-binding sites were involved in the peptide-ice interaction. Our findings suggest that shrimp head-derived AFPs can be developed into functional additives in frozen foods and add more insights into the existing literature on antifreeze peptides.