Exploring the Digestion Behavior of Amorphous Rice Starch: A Holistic Perspective from Hydrocolloid Formation to Metabolism

This study investigates the applicability of first-order enzymatic kinetics in the digestion of amorphous rice starch hydrogels. Structural characterization revealed that increased starch concentration enhances short-range molecular order, which significantly reduces enzymatic digestibility. Using a modified INFOGEST protocol, and rat experiment, both <i>in vitro</i> and <i>in vivo</i> digestion behaviors were comprehensively analyzed. Results showed that as concentration increased, the digestion rate constant (<i>k</i>) decreased notably, and the kinetic model shifted from first-order to zero-order. Animal metabolic experiments further supported this kinetic deviation, indicating a strong relationship between hydrocolloid structure and metabolic response. These findings highlight the limitations of using traditional first-order kinetics to describe starch digestion, suggesting that hydrocolloid concentration is a critical factor affecting digestion and metabolism. This study offers a more comprehensive approach to understanding starch behavior, with implications for dietary starch design and metabolic health research.