Proximate composition, some nutritionally valuable minerals and functional properties of three varieties of Lima bean (Phaseolus lunatus Linn.) flour

Abstract

The proximate composition and functional properties of the flours of three varieties of Lima bean (Phaseolus lunatus Linn.) were determined with and without hulls. The Lima beans were identified by colour as white, brown and dark brown. The percentage protein varied from 21.8 to 26.2 depending on the variety and whether the sample was dehulled. The ash and fat contents did not vary considerably while the fibre depended on variety and whether the sample was dehulled. The mineral analysis showed that zinc, calcium and potassium are more concentrated in the hull, phosphorus more so in the cotyledon while iron is evenly distributed in the hull and cotyledon. The least gelation concentrations for the beans were found to vary from 8% in the brown sample to 12% in the dark brown sample. The water absorption capacities varied from 130% for the white whole seed sample to 142% in the dark brown dehulled sample. The oil absorption capacities varied from 82% to 91.5% depending on whether the sample was dehulled or not. The bean flour formed a reasonably stable emulsion while foaming capacities varied from 22.9% to 29.1% and did not collapse completely until after 36h. The protein solubility of the three varieties showed minimum solubility at about pH 4 and 4.5 for whole and dehulled samples respectively.