The protein, trypsin inhibitor (TI), tannin, phytate, phytic acid phosphorus and in vitro protein digestibility (IVPD) of cultivars of the African yambean (Sphenostylis stenocarpa) – AYB, pigeon pea (Cajanus cajan) – PP and cowpea (Vigna unguiculata) – CP were determined. The protein content of CP (24-28.0%) was higher than those of PP (21-22.5%) and AYB (21-22.5%). The cream and speckled AYB contained more TI (30.9 and 25.3 mg/g) than PP (7.5-14.1 mg/g) and CP (9.8-20.5 mg/g). Apart from the white CP cultivar, they contained more tannin (1.24-1.42 mg/g) than PP (0.14-0.97 mg/g) and AYB (0.71-1.17 mg/g). Phytate was lowest in the AYB (6.30-7.49 mg/g) than PP (8.31-11.31 mg/g) and CP (8.40-9.92 mg/g). Phytic acid contributed 67-74% of the phosphorous in the AYB, 66-75% in PP and 54-59% in CP. The IVPD of the AYB (73.3 + or – 0.7%) was significantly lower (p <0.05) than those of PP (76.34 + or – 0.2%) and CP (77.8 + or – 0.4%). There was a significant negative correlation between TI and IVPD (r = -0.63, p<0.05). There was no significant correlation between IVPD and phytate and tannin contents. There was a positive correlation between protein content and IVPD (r = 0.69**) for the legumes under study. These legumes may pose no serious problems to populations consuming them especially when heat treatment is applied before consumption.
Plant Foods for Human Nutrition 10/1995; 48(3):225-33. DOI:10.1007/BF01088444