Investigation of the molecular mechanism in regulating freeze-thaw deterioration of starch pearls by dextran with different molecular weights

Abstract

Freeze-thaw instability is a critical bottleneck limiting the quality of starch-based foods. This study comprehensively investigated the deterioration mechanisms of starch pearls under repeated freeze-thaw cycles and the regulatory effects of dextran with different molecular weights (MW). Results showed that freeze-thaw induced severe structural damage, water release, and textural hardening. Low-MW dextran (5–20 kDa) provided limited protection due to weak water binding and steric hindrance. While high-MW dextran (200–500 kDa), through its strong hydration and steric hindrance effects, competitively bound water molecules via its hydroxyl groups, effectively inhibiting starch retrogradation; simultaneously, it reinforced the gel network through hydrogen bonding and chain entanglement, reducing the porosity of the system. These changes improved water retention, reduced cooking loss, and conferred superior textural properties. This study elucidates the MW-dependent mechanism of dextran in improving freeze-thaw stability, providing a theoretical basis and practical strategy for enhancing the quality of starch-based products.