Insight into the dynamic molecular mechanism underlying the endogenous polyphenols inhibiting the in vitro starch digestion of highland barley noodles.

[Display omitted] • Endogenous polyphenols (EP) inhibited starch digestion in highland barley noodles. • EP caused disorder and rearrangement of starch molecules' structure. • EP transformed the starch fractions to be more resistant to thermal degradation. • EP reduced rapidly digestible starch by forming V-type structure with amylose. • EP increased resistant starch by lengthening amylopectin chain to form complexes. Highland barley is a type of grain with slow-digesting characteristics. It is worth exploring the impact of non-starch components on starch digestion. In this study, four varieties of highland barley were used to investigate the impacts of endogenous polyphenols (EP) on the relationship between starch structure, physicochemical properties, and the time course digestibility of highland barley noodles. The results showed that EP removal decreased the proportion of long-chain amylopectin and disrupted the crystalline structure, while increasing the short-range ordered structure in the residue. Significant correlations indicated that these structural changes make starch more susceptible to thermal degradation and digestion, causing a 12.60%-52.00% increase in rapidly digestible starch (RDS) and a 12.70%-25.22% decrease in resistant starch (RS). These results revealed the internal factors that affect the slow digestion characteristics of highland barley noodles from the perspective of EP and provide important reference values for a slow digestion diet. [ABSTRACT FROM AUTHOR]