Enzyme resistant starch fractions and dietary fibre.

Starch fractions that are more or less enzyme resistant may behave like dietary fibre, both physiologically and analytically. Ungelatinized granules from potatoes, high amylose maize and green bananas are poorly digested. Starch made resistant to amylase due to new covalent bindings, formed at heat treatment or present in starch derivatives used as food additives, may also be more or less undigestible. "Resistant starch" present in bread and corn flakes is probably retrograded amylose. It is undigestible in the small intestine, but readily degraded by the large bowel microflora. Amylose-lipid complexes seem to be completely absorbed in spite of their resistance to amylase degradation in vitro. Since undigestible starch fractions behave physiologically like non-starch polysaccharides, they should be included in the dietary fibre concept. "Resistant starch" is analysed as glucose based fibre with all current methods except one, which includes an initial DMSO solubilization step.