Structure changes of starch complexed with green tea catechin or lemon peel caffeic acid under thermomechanical-assist low moisture and their prebiotics during in vitro digestion and fermentation

This paper highlighted the structural changes of rice starch complexed with green tea catechin and lemon peel caffeic acid under thermomechanical-assist low moisture, and their prebiotic functions during in vitro digestibility and fermentation were further explained. Extruded starch with caffeic acid, characterized by enhanced short-range order, a distinct fractal structure, and a V-amylose helical arrangement, exhibited slower glucose release due to V-type inclusion crystalline structures and strong hydrogen bondings. Additionally, extruded starch with catechin or caffeic acid changed the composition of gut microbiota by increasing the proliferation of good bacteria and reducing pathogenic microorganisms, which led to a greater synthesis of short-chain fatty acids. According to a PICRUSt2 analysis, the extruded starch with caffeic acid may trigger metabolic alterations via altering the gut flora and increasing bile acid metabolism. Thus, extruded starch with caffeic acid demonstrates significant potential as a prebiotic for developing nutritionally tailored starch-based foods.