Resistant starch was isolated from wheat-based foods such as chapati, phulka and poori and structurally characterised. Perchloric acid digestion and sized exclusion chromatography gave pure resistant starch, which was shown to be a linear 1,4-linked alpha -D-glucan essentially derived from retrograded amylose fraction. The latter is dependent on the severity of the processing treatment as well as the levels of gluten and damaged starch in the wheat flour. (C) 2001 Academic Press.