Physicochemical interactions between rice starch and caffeic acid during boiling

Defining the physicochemical interactions that may occur during fortification of starchy foods may be of great importance in food science. In this study, DSC and H-1 NMR techniques were acquired in order to examine the potential interactions between rice starch and caffeic acid, after following a hydrothermal treatment that may be used for rice fortification applications. According to DSC studies, significant changes were observed in starch thermal characteristics depending on the amount of caffeic acid added in starch-water mixture prior to heating. These changes could be attributed to the phenolic acid being probably embedded into starch-water matrix during heating and this may have altered its thermal properties and stability. Moreover, NMR studies of hydrothermally treated samples containing rice starch or caffeic acid and their mixtures showed a possible interaction of rice starch polysaccharides through H-bond formation with the phenolic acid.