Promoting starch interaction with caffeic acid during hydrothermal treatment for slowing starch digestion

The control of the formation of starch-guest inclusion complex is significant for slowing starch enzymatic digestion. This work opened a pathway to promote the formation of starch-caffeci acid inclusion complex via simply heating and cooling of starch slurry with caffeic acid. Caffeic acid was hardly but freely dissolvable in cold and hot water, respectively, which enabled caffeic acid in hot solution potentially interacted with starch to form starch-caffeic acid inclusion complex during the cooling. Molecular dynamic simulation and starch structures verified that starch-caffeic acid inclusion complex formed via two steps: (i) heating the cold slurry containing starch and supersaturated caffeic acid; (ii) reasonably cooling the hot solution. The formation of the inclusion complex was promoted via increasing the cooling rate and shear speed during the cooling, which increased the resistant starch content by ca. 5%–18% compared with native cooked starch complexation without caffeic acid.