Effect of processing on some antinutritive and toxic components and on the nutritional composition of the African oil bean seed (Pentaclethra macrophylla Benth)

Meals of raw, cooked and fermented oil bean samples of African oil bean seeds ( Pentaclethra macrophylla Benth) were analysed for proximate composition, mineral content, presence and levels of trypsin inhibitors, tannins, phytic acid, cyanide, aflatoxin B 1 and B 2 . The moisture content of the raw samples was 275.0 g kg −1 as is and on a dry matter basis the beans contained (g kg −1 ) 26.0 ash, 255.0 protein, 462.0 fats, 71.0 fibre and 186.0 carbohydrate. Compared with raw samples the fermented material (ugba) had significantly ( P < 0.05) higher moisture (440 g kg −1 as is), fat (612.0 g kg −1 DM) and significantly ( P < 0.05) lower protein (228.0 g kg −1 DM), ash (132.0 g kg −1 DM) and carbohydrate (186.0 g kg −1 DM). Minerals in raw seed were (g kg −1 DM) phosphorus (3.0), calcium (1.0) magnesium (2.0), potassium (6.5), sodium (455.0), manganese (25.3), iron (19.0), copper (27.0) and zinc (42.0). Except for zinc and calcium the minerals were leached significantly ( P < 0.05) during cooking and fermentation. Quantities of manganese, copper and zinc in ugba appear adequate for dietary purposes. Trypsin inhibitor activity of raw beans decreased during cooking by 98% while fermentation increased the activity of the cooked sample by 1%. Phytic acid and tannins were significantly reduced ( P < 0.05) during processing. No cyanide or aflatoxins B 1 and B 2 were detected.