Effects of roasting and soaking on the proximate composition and functional properties of selected tropical legumes

Abstract

Proximate composition and functional properties of roasted and soaked Afzelia africana “akpalata”, Brachystegia eurycoma “achi” and Detarium microcarpum “ofo” were studied. Result indicated no significant differences (P>0.05) in ether extract of the processed legumes but roasted B. eurycoma, A africana and D. microcarpum had the highest values. Also, no significant differences (P>0.05) were observed in the crude fibre and moisture contents of the three legumes. Control (raw) and soaked B. eurycoma and A. africana compared very well in ash contents but no significant differences (P>0.05) were observed in the raw, roasted and soaked D. microcarpum legumes. Roasting and soaking improved the crude protein contents of B. eurycoma and D. microcarpum while there was a decrease in the protein contents of A. africana. Although, the swelling index of the processed B. eurycoma and D. microcarpum respectively compared favourably with their raw legumes, the soaked (2.16 ml/g) A. africana was significantly better than the raw (1.7 ml/g) and the roasted (1.50 ml/g) legumes in swelling index. Roasted and raw A. africana showed no significant difference in oil absorption capacity while the roasted (8.00 ml/H20/g flour) D. microcarpum was better than the soaked (7.00 ml/H20/g flour) and raw (6.10 ml/H20/g flour) in water absorption capacity. Least gelation concentrations for raw, roasted and soaked legumes were indicated as 12%, 8% and 12% (B. eurycoma). 18%, 16% and 14% (A. africana) and 6%, 4% and 6% (D. microcarpum) respectively. Roasting and soaking decreased the emulsion capacities of B. eurycoma, A. africana and D. microcarpum. The three processed legumes were significantly higher than their raw legumes in thermal gelation temperature.

Keywords: Roasting, soaking, proximate composition, functional properties, tropical legumes.


(Global Journal of Pure and Applied Sciences: 2003 9(2): 177-182)