Effect of Processing on Functional Properties of Yam Beans (Sphenostylis stenocarpa)

Abstract

The proximate and functional properties of yam bean were determined in five-flour form as raw, boiled, fermented, roasted and malted. The functional properties determined were water absorption, fat absorption gelation, emulsion and foam capacities as well as foam stability. An improvement was observed in protein under all the processing conditions. Protein content ranged from 20.43% in raw flour to 23.63% in malted flour. Fermentation significantly (p<0.05) increased the fat content of the flour. The emulsifying and foaming capacities (50.7% and 40.20%, respectively) observed for raw flour were significantly higher than for the processed flours. Gelation was significantly (p<0.05) increased and decreased respectively, by fermentation and malting. The water absorption capacity ranged from 131.9% in raw flour to 218.8% in boiled flour. There was no significant (p>0.05) difference in the fat absorption capacity of the flours except the fermented flour (0.40 ml/g) which was significantly lower than the value (0.73 ml/g) obtained for boiled flour. Though a high foaming capacity was observed for raw flour, this was less stable compared with the processed flours. Yam bean flour was found to exhibit good functional properties and can offer a great potential in various food systems.