Comparative nutritional and functional properties of selected underutilized legumes

Abstract

Underutilized and neglected legumes have numerous nutritional potentials with great contributions to food security but they are usually excluded from research and development agenda. This study evaluates the nutritional and functional properties of six different underutilized and neglected legumes; Lima bean (LB) (Phaseolus lunatus) (2006-009), Bambara groundnut (BG) (Vigna subterranea) (TVSU- 1482), winged bean (WB) (Psophocarpus tetragonolobus) (Tpt-48), jack bean (JB) (Canavalia ensiformis) (Tce-4), sword bean (SB) (Canavalia gladiata) (Tcg-4) and African yam bean (AYB) (Sphenostylis stenocarpa) (TSS-95) from the Genetic Resources Unit (GRU), International Institute of Tropical Agriculture (IITA), Ibadan, Oyo State, Nigeria. Nutritional and functional properties were evaluated using proximate composition, mineral analyses and functional properties like bulk density, water absorption capacity, oil absorption capacity, emulsion capacity and dispersibility. All the procedures were carried out using standard protocols. Statistical analysis was done using descriptive statistics. Results of proximate analysis showed that crude protein ranged from18.88 0.15%(WB) to 26.60±0.14%(AYB), crude fat ranged from 1.84 0.02% (JB) to 6.39 0.03% (BG), crude fibre ranged from 3.70 ±0.00% (AYB) to 5.04 0.03% (SB), ash ranged from 3.10 ± 0.14% (AYB) to 4.66 0.02% (LB), nitrogen free extract ranged from 55.60 0.04% (SB) to 62.97 0.12% (WB), moisture content ranged from 5.75 0.48% (AYB) to 10.77 0.03% (JB), dry matter ranged from 89.23 0.03% (JB) to 94.25 ± 0.488% (AYB) and gross energy ranged from 4.39 0.003 kcal/g (SB) to 4.66 0.00 (BG). Mineral content results revealed that calcium varied from 0.14 0.000% (LB) to 0.23 0.0003% (AYB), phosphorus varied from 0.20 0.0001% (AYB) to 0.38 0.00% (BG), sodium varied from 0.12 0.00% (LB and WB) to 0.35 0.0006% (AYB), potassium varied from 0.69 0.00% (LB) to 1.12 0.00% (BG), magnesium varied from 0.15 0.0002% (AYB) to 0.27 0.000% (BG) and iron varied from 44.84 0.03 (mg/g) (WB) to 80.98 0.0007(mg/g) (AYB). Results of functional properties showed that bulk density ranged from 0.45±0.04 g/mL (WB) to 0.77±0.08 g/mL (SB), water absorption capacity ranged from 168.33±0.03 g/100g (LB) to 183.62±0.01 g/100g (SB), oil absorption capacity ranged from 146.54 ±0.02 g/100g (LB) to 161.55±0.02 g/100g (JB), emulsion capacity ranged from 79.67 ±0.02 g/100g (LB) to 89.46±0.02 g/100g (SB) and dispersibility ranged from81.0±1.41%(SB) to 86.5±0.71% (BG). The study concluded that all the underutilized legumes have varying nutritional and functional properties, which should be exploited for nutritional benefits and industrial applications, as a solution to the problem of food shortage, especially in the developing countries.