Structural changes of type 3 resistant starch during in vivo digestion using a duodenum and ileal cannulated miniature pig model

Changes in the structure of type 3 resistant starch (RS3) during oral-gastric digestion, oral-gastrointestinal digestion, and oral-gastrointestinal-colonic digestion were assessed using a miniature pig model with duodenal and ileal cannulas. Compared to normal maize and high-amylose maize starch (RS2), self-prepared RS3 maintained stable blood glucose concentrations and preserved its orderly crystalline structure, indicating its higher resistance to enzymatic digestion. During in vivo digestion, partial V-type polymorphs (characterized by diffraction peaks 12.7° and 19.7°) and partial B-type polymorphs (characterized by diffraction peaks 5.2° and 16.8°) were found to be more susceptible to hydrolysis. Notably, the crystalline structures corresponding to the diffraction peaks at 10.3°, 22.3°, and 26.0° (associated with B-type polymorphs) were inferred to be resistant to enzymatic hydrolysis. The intact aggregate structures of RS3 were still present in small intestinal digesta until 300 min. The undigested RS3 entered the large intestine and was fermented by colonic bacteria. This study provides essential knowledge for the targeted development of RS3 with a high RS content.