Mechanistic studies on the effect of endogenous proteins on the starch retrogradation characteristics of corn before and after postharvest ripening.

The corn starch-protein complexes before postharvest ripening (JD-0) and after postharvest ripening (JD-40) were subjected to protease treatment, and the influence of protein on starch retrogradation was studied. Kinetic studies of starch retrogradation showed that protein reduced the retrogradation rate constant (k) of starch by 25.46 % (JD-0) and 7.48 % (JD-40), respectively. This was mainly reflected in the inhibition of short-range order, relative crystallinity and helix structure formation in the retrogradation process. In addition, low field strength nuclear magnetic resonance (LF-NMR) analyses also revealed that proteins inhibited starch retrogradation by isolating the precipitation of free water during retrogradation, causing the decrease in the viscoelasticity and firmness of the starch gel. Therefore, the inhibitory effect of proteins on starch retrogradation before postharvest ripening of corn-based food products was more relevant.