PRODUCTION AND FORTIFICATION OF ‘OGI’ USING BAMBARA NUT (Vigna subterrenea)

Abstract

This study was undertaken to improve the nutritive value of ‘ogi’. Bambara nut, a nutritious legume which cotains65% carcohydrate, 18% protein and 6.5% fat was used. Fortification level was 40% Bambara with 60% of the commonly known substrates i.e maize, millet and sorghum i.e 3:2. The control was constituted with 666.6g of each of Maize, Millet and Sorghum to make 2kg of fermenting substrate. The three grains i,e maize millet and sorghum were also used to produce ‘ogi’ as sole substrates. ‘ogi’ was also produced using only Bambara nut. The substrates were steeped for seventy-two hours each (primary fermentation). Samples were taken for microbiol’ogi’cal and physicochemical analysis at 0, 24, 48 and 72hrs respectively. In the same vein, samples were taken at 0, 24 and 48hrs during secondary fermentation for microbiol’ogi’cal and physicochemical analysis i.e pH and total titratable acidity (TTA). Bacteria isolated include Lactobacillus fermentum, L. plantarum, Bacillus subtilis, Flavobacterium rigense, Proteus vulgaris, Flavobacterium aquantile, Bacillus alvei and the fungi include Geotrichum candidum, G. fermentum, Penicillium atrovene, Aspergillus niger, Rhizopus oryzae etc. A drop in pH of the fermenting substrates was noticed as fermentation progressed and this was accompanied with increase in TTA (Total Titratable Acid) in all cases. There was also bacterial succession as the aerobic organisms which were prevalent at the onset of fermentation gave to anaerobic ones which are members of the lactic acid bacteria (LAB). Temperature was constant at 30±2°C. Proximate analysis of the final products revealed more than 100% improvement in protein composition for fortified sorghum and maize ‘ogi’ but 53.82% improvement for fortified millet ‘ogi’. It also increased the fat content of the fortified sorghum, maize and millet ‘ogi’ by 38%, 57% and 174% respectively. Fortifying these cereals with bambara nut also improved the ash content of fortified sorghum and maize ‘ogi’ by 23.89% and 15.33%. Fortification did not improve the ash content of millet ‘ogi’. There was no significant improvement in the fibre content in all the three cases of fortification. The mineral analysis of the ‘ogi’ products shows that ‘ogi’ made from bambara nut contain higher level of minerals compared to the rest. Analyses of the ‘ogi’ products for anti-nutrients show that they contain safe and acceptable levels, though ‘ogi’ made entirely from Bambara nut contain high amount of some of the antinutrients. The organoleptic assessment which was designed to measure appearance, sourness, flavor, taste, aroma\smell, acceptability and comparability was done by 32 untrained panelists. The overall acceptability at 5% confidence level revealed that sample C (maize fortified ‘ogi’) was the most acceptable in terms of acceptance, taste, aroma\smell, acceptability and comparability. Sample E which is the second most acceptable sample scored highest in sourness and taste. In all the qualities measured, sample B (‘ogi’ made from only bambara nut) scored least except for appearance where it did better than sample D the least preferred in terms of appearance. Sample B was the least acceptable of all the samples.