STRUCTURAL DISCREPANCIES IN RESISTANT STARCH OBTAINED IN-VIVO IN HUMANS AND IN-VITRO

In-vivo resistant starch (RS) was collected at the end of the human ileum by an intubation technique after ingestion of two partly resistant starches (retrograded (R) or complexed (C) high amylose maize starch). In-vitro RS fractions were prepared enzymatically from R and C according to three methods of RS determination in food. Physicochemical characteristics of these two different fractions were compared. The ileal RS appeared to consist of three fractions: a first population of high molecular weight alpha-glucans attributed to amorphous potentially digestible material, a second made of B-type retrograded amylose crystallites and a third containing oligosaccharides. The in-vitro RS fractions showed no high molecular weight molecules, due to more extensive hydrolysis in the in-vitro procedure. Therefore, none of the in-vitro RS determinations allowed the isolation of a fraction qualitatively similar to in-vivo RS.