Preserving Daifuku quality via static and pulsed magnetic freezing: Associations with water state and structural changes.

This study investigated magnetic-field-assisted freezing (MF) to mitigate post-thaw quality deterioration in Daifuku. Static magnetic field (SMF, 4-8 mT) and pulsed magnetic field (PMF, 6 mT, 0.4-0.8 Hz) were compared with regular freezing (RF) at -20 °C. MF treatment shortened phase-transition time, with the greatest reduction reaching 32.08% under PMF. Compared with RF, MF-treated samples exhibited improved surface morphology, reduced starch short-range ordering, and better preservation of ordered protein secondary structures. RF caused severe post-thaw hardening relative to fresh Daifuku (+639.6%), whereas all MF treatments substantially alleviated this change. Among the frozen groups, PMF at 0.8 Hz showed the best overall texture retention, with a hardness increase of only 9.45% relative to fresh Daifuku. DSC and LF-NMR results further indicated that MF mitigated unfavorable water-state changes in Daifuku skin. Overall, MF-assisted freezing substantially alleviated freezing-induced quality deterioration, with SMF and PMF showing different quality-preserving advantages.