Nutritionally important starch fractions in cereal based Indian food preparations

Recent research studies have invalidated the earlier assumptions regarding the rate of digestion of carbohydrates. Hence, in the present study the rate and extent of starch digestion in vitro was measured in 10 cereal-based Indian food preparations (with/without accompaniments). The selected foods included chapathi, dosa, idli, pongal, poori, ragi roti, rice roti, rice flakes upma, semolina idli and upma and the accompaniments — cooked dhal, chutney and potato palya. In view of the nutritional importance of starch, the major starch fractions viz., rapidly digestible starch, slowly digestible starch (SDS) and resistant starch as defined by Englyst [Englyst, H. N., Kingman, S. M., & Cummings, J. H. (1992). Classification and measurement of nutritionally important starch fractions. European Journal Clinical Nutrition, 46(2), 333–350] were measured, by using controlled enzymic hydrolysis with pancreatin and amyloglucosidase. In addition, rapidly available glucose (RAG) was measured and a starch digestion index was derived. Dietary fiber components (soluble and insoluble fiber) were measured by the enzymatic method [Asp, N. G., Johansson, C. G., Hallmer, H., & Siljestrom, M. (1983). Rapid enzymatic assay of insoluble and soluble dietary fiber. Journal of Agricultural Food Chemistry, 31, 476–482]. The results indicate that the course of starch hydrolysis was not only characteristic for each food but also appears to be affected by the addition of accompaniment. Also, while the correlation between RAG and SDS did not attain significance in foods with accompaniment, a significant inverse correlation (r=−0.68, P<0.05) was seen in foods without accompaniment. It is evident that starch digestibility in Indian foods is influenced by the accompaniment rather than the cereal base.