Changes in the Dietary Fiber (Resistant Starch and Nonstarch Polysaccharides) Content of Cooked Flours Prepared from Three Chinese Indigenous Legume Seeds.

Abstract

The effects of cooking on the dietary fiber (DF) content, which included resistant starch (RS) and nonstarch polysaccharides (NSP), of flours from Phaseolusangularis, Phaseolus calcaratus, and Dolichos lablab seeds, indigenous to China, were evaluated. The cooked legume flours were prepared by milling boiled and freeze-dried legume whole seeds. Total DF contents of all cooked flours were higher than those of the raw ones. The results showed an increase of NSP and RS to various extents with increasing cooking time of the flours. In the NSP of the legume flours, both the soluble and insoluble fractions increased during cooking, and a redistribution of the soluble and insoluble NSP components was observed. Generally, cooking increased the solubilization of the NSP in the legume seed flours, which might be important for their use as soup ingredients for therapeutic purposes. The increase of RS in the legume flours could be mainly due to the presence of cell-enclosed starch and retrograded starch formed during cooking. Such increase in the RS content of the cooked legume flours might have beneficial physiological effects for humans.