Insight into the multi-scale structure changes and mechanism of corn starch modulated by different structural phenolic acids during retrogradation

This study aimed to evaluate the effect of the selected phenolic acids, i.e., cinnamic acid (CIA), caffeic acid (CA), and ferulic acid (FA), on corn starch (CS) retrogradation and their potential interaction mechanism. Differential scanning calorimetry (DSC) results revealed that the three selected phenolic acids decreased the retrogradation enthalpy of CS. It indicated that the selected phenolic acids inhibited CS retrogradation. The poor short-range molecular order and low relative crystallinity (RC) of CS were induced by phenolic acids during retrogradation. CA showed superior performance among the three. Small-angle X-ray scattering (SAXS) results demonstrated that CS treated with the selected phenolic acids possessed much thinner semi-crystalline lamellae and loose structures compared to CS. CA induced the thinnest semi-crystalline lamellae compared with CIA and FA. It was attributed to the contribution of the interaction between the selected phenolic acids and CS. Isothermal titration calorimetry results indicated that CA interacted with CS through hydrogen bonding. Hydrophobic interaction was crucial when CS individually interacted with FA and CIA. From the structural point of view, the interaction type between the selected phenolic acids and CS depended on the substituted group on the benzene ring of the selected phenolic acids. This study demonstrated how starch retrogradation was modulated by phenolic acids in detail, which would provide fundamental data for the development of CS products with longer shelf lives.