ABSTRACT

The effect of period of germination on the crude protein content of defated soybean flour and quality of soybean oil were studied. Crude fat decreased after 72 hours of germination from 21.900 to 13.860. Crude protein content increased from 43.82% on the zero day to 63.74% after 72 hours. Germination was found to increase significantly (P<0.05) the saponification value (183.7 to 200.05), peroxide value (2.50 to 8.25), iodine value (34.60 to 39.04), thiobabituric acid value (0.61 to 8.51) and colour intensity (0.26 to 6.70). Eight lactic acid bacteria strains were isolated from ogi, nunu and soybean and four belonged to the genus Lactobacilli, two to the genus Leuconostoc, one to to the genus Pediococcus and one strain was not determined. Four out of the eight isolates were able to produce bacteriocin. The bacteriocin produced by these organisms inhibited the reference strains Staphylococcus aureus (ATCC 12600) and Escherichia co/i (ATCC 117755). The inhibition spectrum (zones) of these organisms against E. co/i and S. aureus varied from 7.333mm to 15.00mm and 9.677mm to 19.33mm respectively. Optimization of probiotic malted and unmalted soy yoghurt production were carried out using response surface methodology. The central composite design with three factors at five levels was used. Process variables were inoculum size (A), incubation period (B) and substrate concentration (C). Changes in the four responses (pH), total solid (TS), total titratable acidity (TTA) and total microbial load (TML) were monitored during fermentation of the soy yoghurt for 7 days. Minimum and maximum values of these responses for fresh malted soy yoghurt samples were 6.43 to 6.60 for pH, 6.80°h to 10.73% for total solid, 0.10 to 1.45/o for total titratable acidity and 6.2 X iO4to 14.1 X cfu/ml for total microbial load while on the 7th day, the values were 4.36 to 4.48 for pH, 5.22% to 9.37% for total solid, 0.27 to 401% for total titratable acidity and 90.7 X i0 to 144.4 X tO4cfu/ml for total microbial load. The maximum and minimum values on the zero day for unmalted soy yoghurt were 6.32 to 6.71 for pH, 585 to 9.20% for total solid, 0.041 to 0.088% for total treatable acidity and 5.5 X i0 to 10.8 X iü cfu/ml for total microbial load while on the 7th day were 4.16 to 4.50 for pH, 4.35 to 7.20% for total solid, 0.281 to 3.00% for total treatable acidity and 97.7 X to 14.24 X cfu/ml for total microbial load. The sensory attributes showed that samples P0 and RQ for malted soy yoghurt and sample XY for unmated soy yoghurt competed favourably with the conventional dairy yoghurt.