Multi-target cryoprotection of gelatin-tea polyphenol compounds on surimi through ice inhibition and component stabilization

In this study, the multi-cryoprotective effects of gelatin-tea polyphenol compounds were explored by ice inhibition and component stabilization. The structural properties of these gelatin-tea polyphenol compounds were characterized using Fourier Transform Infrared spectroscopy and X-ray Diffraction analysis. The freezing behavior and antifreeze capabilities of the compounds were investigated through Differential Scanning Calorimetry and ice recrystallization inhibition assays. Additionally, the cryoprotective effects of the compounds at various concentrations (1%, 2.5%, and 4%, w/w) on myofibrillar proteins were examined. The hydrogen bond interactions between the amino groups of gelatin and the phenolic hydroxyl groups of polyphenol facilitated the formation of compounds. The GP-5 group has the reduced freezing point (-1.68 ℃) and frozen water content (85.32%) compared to the control group. Notably, the addition of 2.5% (2.5G group) or 4% GP-5 (4G group) consistently demonstrated superior and stable ice-inhibition performance against various frozen conditions. Also, 2.5G group exhibited comparable cryoprotective effects to the commercial antifreeze group (S group), with lower mass loss (1.37%), surface hydrophobicity (33.90 µg), and carbonyl content (1.06 nmol/mg). Furthermore, the 2.5G group also demonstrated significant tissue integrity against ice-induced damage, as indicated by similar fractal dimension to that of the S group. Size measurements and SDS-PAGE analysis further suggested that the ice-inhibiting effects and compositional stabilization from compounds enhanced protein structure stability. Overall, the multi-cryoprotective roles of compounds in surimi offer valuable insights for the development of advanced antifreeze agents.