Cryoprotective Activity and Action Mechanism of Antifreeze Peptides Obtained from Tilapia Scales on Streptococcus thermophilus during Cold Stress

Cold stress adversely affects cell viability and acidification, and new cryoprotective methods continue to be needed in cold-chain food industry. Given this, we investigated the cryoprotective effects and action mechanism of antifreeze peptides obtained from tilapia scales (TSAPP) on Streptococcus thermophilus during cold stress. Our results showed that the molecular weight of TSAPP ranged from 180 to 2000 Da and its thermal hysteresis activity was 0.29 degrees C. Growth of S. thermophilus was improved after treatment with TSAPP (1 mg/mL) under cold stress. This growth was notable when compared with the effects of other cryoprotectants. Furthermore, TSAPP improved the metabolic activity of S. thermophilus during cold stress. TSAPP likely offered its cellular protection by maintaining cell membrane fluidity through hydrogen bonding of the phospholipid bilayer. These results indicate that TSAPP has potential as a novel biological peptide material with cryoprotective activity for future use in probiotic or other processed food applications.