Cryoprotective mechanisms of membrane-separated fractions from thawed drip: Insights from a myosin model.

This study aimed to investigate cryoprotective activity of thawed drip membrane-separated components (> 10 kDa and < 10 kDa) and their cryoprotective mechanism based on a myosin model. Both fractions exhibited stable hydroxyl structures and strong thermal hysteresis activity, significantly enhancing survival rate of Streptococcus thermophilus under freeze-thaw stress. Using myosin as a model system, both fractions suppressed freezing-induced increases in surface hydrophobicity, carbonyl and particle size, while mitigating decreases in free sulfhydryl and fluorescence intensity, thereby alleviating protein aggregation and conformational denaturation. Intermolecular force and molecular docking analyses revealed that >10 kDa fraction interacted with myosin mainly through non-specific binding, while the peptide KELASQPDVDGFLVGGASLKPEFVDIINAK in <10 kDa fraction bound to key myosin domains via hydrogen bonding and hydrophobic interactions. These findings offer new insights for developing natural cryoprotectants to enhance quality stability of frozen food products.