Chemical composition and in vitro starch bioavailability of Phaseolus vulgaris (L) cv Mayocoba

Common beans of the Mayocoba variety were cooked (178 min) and evaluated regarding their chemical composition and starch digestibility in vitro. Mean physical characteristics of the Mayocoba grain were: thousand-kernel weight, 443.0 (+/- 0.98)g; length, 12.45mm; width 7.84mm and thickness, 6.44mm. Total starch content in Mayocoba bean was 40.24% (dmb). The available starch was 22.87%, whereas resistant starch accounted for 6.4% and retrograded resistant starch represented 3.3% of the cooked seed weight. None of these values changed with storage time. The Mayocoba variety presented values of soluble indigestible fraction of approximately 8.0% and insoluble indigestible fraction of 36%, which did not change with storage. Both simple enzymatic hydrolysis rate and hydrolysis index (HI= 36%) indicated a slow hydrolysis of Mayocoba starch. HI-based predicted glycemic index was 39%, all of which suggested a 'slow carbohydrate' feature for this bean. (C) 2004 Society of Chemical Industry.