Development of novel food-derived antifreeze proteins and peptides: investigating structure-function relationships in ice recrystallization inhibition

The formation and growth of ice crystals during frozen storage negatively affect the quality of frozen foods, necessitating the development of novel, safe, and effective ice recrystallization inhibition (IRI) agents. Protein hydrolysates are promising alternatives due to abundant raw materials and safety for consumption. The first chapter explored succinylation of zein and gelatin hydrolysates, showing that modified peptides significantly improved IRI activity by reducing ice crystal size by approximately 40%, linked to enhanced amphiphilicity. The second chapter investigated wheat glutenin hydrolysates prepared by Alcalase and trypsin. Trypsin-derived hydrolysates displayed higher IRI activity, especially under low ionic strength and in CaCl₂ solutions, with increased α-helix content correlating to improved antifreeze function. The third chapter identified two wheat flour-derived water-soluble proteins, including WDAI-3, with strong IRI activity. Molecular dynamics simulations confirmed that WDAI-3’s antifreeze behavior was linked to structural rigidity and protein-water interactions. The fourth chapter demonstrated that gelatin hydrolysates’ IRI activity was enhanced by xanthan gum (XG), even at low concentrations (0.1%), with stabilization above 0.4%. Molecular weight, mixing time, and secondary structure (rich in β-sheets and α-helices) further influenced the IRI activity of XG-gelatin complexes. The final chapter employed molecular dynamics simulations to examine peptides with varied chain lengths and secondary structures derived from trypsin hydrolysis, revealing a strong correlation between structural features and antifreeze efficiency. Overall, this dissertation provides foundational insights into designing and understanding antifreeze peptides for food preservation and other biomaterial applications.