Mechanisms of egg white delaying the retrogradation of rice bread during short-term low-temperature storage

Rice bread (RB) is valued for its soft texture and special flavour but is highly susceptible to quality deterioration, particularly deterioration driven by starch retrogradation and water loss during storage. This study elucidated mechanisms by which egg white (EW) delayed RB retrogradation during short-term low-temperature storage. Considering EW's wonderful functional properties, its impact on water distribution and retrogradation was assessed using texture analysis, X-ray diffraction (XRD), differential scanning calorimetry (DSC), and low-field nuclear magnetic resonance (LF-NMR). Results demonstrated that 0.9% EW significantly decreased the RB hardness to (56.72 ± 1.90) N, with a reduction of 59.37% compared to the control. EW effectively inhibited retrogradation, lowering relative crystallinity (RC) from 10.65% to 9.48% and reducing retrogradation enthalpy (ΔH) to 1.92 J/g. Furthermore, LF-NMR analysis revealed that EW altered water distribution: it decreased the amounts of bound water (A21, A22) while increasing weakly bound water (A23) and free water (A24), indicating a bidirectional equilibrium in internal moisture migration. This study demonstrated that EW retarded RB retrogradation by enhancing internal water mobility and distribution, thereby inhibiting the aggregation and recrystallization of starch molecular chains. The research provided a novel, natural strategy for RB anti-retrogradation with both theoretical and practical value.