Type III Resistant Starch Prepared from Debranched Starch: Structural Changes under Simulated Saliva, Gastric, and Intestinal Conditions and the Impact on Short-Chain Fatty Acid Production

Type III resistant starch (RS3) has high resistance to enzymatic digestibility and benefits colonic bacteria by producing short-chain fatty acids (SCFAs) via fermentation. Studies have delineated RS preparation and the description of RS fractions with different types of starch, but the digestion process has received little attention. The molecular and crystalline structure changes, thermal properties, and SCFA content of RS3 obtained from debranched starch were investigated in simulated salivary, gastric, and intestinal digestion systems. The average degree of polymerization and the melting enthalpy change of the digested RS3 residues increased; a high molecular order was reflected by the higher relative crystallinity. Fine structural changes suggested that enzyme-resistant starch might form during digestion by the rearrangement of short amylose chains into enzyme-resistant structures with higher relative crystallinity. After fermentation of human feces, RS3 increased the SCFA content, especially of butyric acid, indicating that this recrystallized RS3 could be a new prebiotic product.

Automated summary

The study investigated the changes in molecular and crystalline structure, thermal properties, and SCFA content of Type III resistant starch (RS3) obtained from debranched starch in simulated digestion systems. The results showed that digested RS3 residues had increased average degree of polymerization and melting enthalpy, indicating higher molecular order and relative crystallinity. The fine structural changes suggested the formation of enzyme-resistant starch during digestion, leading to higher relative crystallinity. Fermentation of human feces with RS3 showed an increase in SCFA content, particularly butyric acid, suggesting the potential of recrystallized RS3 as a new prebiotic product.