Effect of polyphenolic compounds on starch retrogradation and in vitro starch digestibility of rice cakes under different storage temperatures

The effects of matcha (MAT), tea polyphenols (TP) and catechin (CAT) on rice cakes during storage for 180 days at 4 °C and 25 °C were evaluated using textural properties, water migration, XRD spectra and in vitro starch digestibility. Polyphenolic compounds, especially TP and CAT, primarily retarded the starch retrogradation of rice cakes by interacting with starch chains, which lowered the content of bonded water, as indicated by water migration and a lower relative crystallinity. The reduction of hardness and increase of adhesiveness was attributed to inhibition of starch chain cross-linking by the polyphenolic compounds (CAT and TP in particular). The polyphenolic compounds synergistically affected starch re-association at a high storage temperature (25 °C) and decreased the variance of rice cake quality caused by starch retrogradation during storage at 4 °C. The starch digestion of rice cakes was inhibited by polyphenolic compounds, especially CAT, which concomitantly increased the content of resistant starch. Furthermore, polyphenolic compounds reduced the changes of various properties which caused the stabilization of rice cake quality during long-term storage. Our study could provide an alternative for improving rice cake quality affected by storage.