Resistant starch

The term ‘resistant starch’ was originally used to designate a starch fraction that resisted pancreatic amylase/pullulanase degradation in vitro after dispersion in boiling water; following solubilization with potassium hydroxide or dimethylsulphoxide this fraction could be hydrolysed by amyloglucosidase. A similar starch fraction, which consists of retrograded amylose, is included in ‘dietary fibre’ as determined by methods that do not employ these solubilizing agents. Recently, the resistant starch conceptr was extended to include all starch and starch degradation products not absorbed in the small intestine of healthy individuals; according to this physiological definition, raw B-type starch granules and physically inaccessible starch, for example, in addition to retrograded amylose, are identified as forms of resistant starch. The measurement of resistant starch presents analytical problems, and no in vitro procedure has yet been documented to recover all forms of starch that are inaccessible in vivo. Animal models and in vitro methods that simulate conditions in vivo as closely as possible are needed. Such work as well as evaluation of the physiological effects of resistant starch are the topics of a European collaboration within the FLAIR programme of the Commission of the European Communities.