Physicochemical studies on resistant starch in vitro and in vivo

Resistant starch (RS), produced in vitro by hydrolysis of retrograded pea starch gels and amylose gels by porcine pancreatic alpha-amylase, was characterised by X-ray diffraction, size exclusion chromatography and methylation analysis. These techniques showed that RS in vitro consisted of semi-crystalline, mostly linear material that was present in two main molecular size subfractions (DPn > 100 and DPn 20-30) with a third, minor subfraction (DPn less than or equal to 5). The extent of retrogradation of amylose was found to be of primary importance in determining the RS content of starch. Analysis of in vivo RS, recovered during an ileostomy study, produced results that were similar to those obtained from RS in vitro. An in vitro model for the structure of resistant starch is proposed. (C) 1996 Academic Press Limited