Ethanol promoted lauric acid interaction with rice starch during steaming

Fatty acids could form inclusion complexes with starch with the aid of mechanical treatment to reduce starch digestibility. However, methods to enhance the interaction between starch and fatty acids without extensive mechanical treatment remained largely unexplored. This study investigated the effects of synchronous complexation of lauric acid (LA) and ethanol on the structure and digestibility of starch during steaming. The complexation of either ethanol or LA alone significantly enhanced the ordered structures of starch, which increased the content of resistant starch (RS) from 13.17 % to 19.60 %-24.58 %. Furthermore, the synchronous complexation of LA and ethanol synergistically promoted the formation of single helix and V-type crystals, resulting in an RS content increase to 28.75 %-35.21 %. The underlying mechanism for these observations was related to changes in LA solubility within the system. According to the dynamic simulation results, LA could readily interact with starch primarily through van der Waals forces in water system, but this interaction diminished in a system containing both water and ethanol. Ethanol promoted LA dissolution in starch slurry and resulted in the formation of LA monomers, but LA solubility reduced while ethanol evaporation during the steaming and in turn enhanced LA interaction with starch to form thermostable complexes. These findings provided a viable pathway for promoting slowing starch digestibility through enabling fatty acids interaction with starch.