Proximate composition, minerals, tannins, in vitro protein digestibility and effect of cooking on protein fractions of hyacinth bean (Dolichos lablab)

Four hyacinth bean cultivars (Dolichos lablab L.) were used in this study. Protein contents varied from 22.7-26.1%, fat contents 1.1-2.0%, moisture contents 7.8-8.1%, ash contents 3.8-4.3%, fibre contents 9.3-10.9% and carbohydrate contents 48.3-53.6%. Phosphorus values ranged from 305-312, magnesium : 167.4-231.1, sodium: 6-9 and potassium: 183.3-214 mg/100 g. Tannin contents of the four hyacinth bean cultivars were in the range of 201-353 mg/100 g, while the in vitro protein digestibility of the four cultivars was in the range 59.2-62.0%. The variation in protein fractions was : albumin 1.8-2.5%, globulin 69.9-81.2%, prolamin 2.7-4.4%, G1-glutelins 0.8-1.8%, G2-glutelins 1.1-3.0%, G3-glutelins 10.0-11.9% and insoluble proteins 0.2-9.9%. Two hyacinth bean cultivars, selected for their higher albumin and globulin fractions, were cooked in 150 ml of boiling distilled water under reflex. The protein fractions of the cooked seeds were determined. Results indicated that albumin and globulin fractions decreased significantly (p1-glutelins, G2-glutelins and G3-glutelins fractions.