ABSTRACT

Soybean flour was produced from soybean seeds and blended with wheat flour at different proportions. The composite flour samples were analyzed for the functional properties. The flour samples were used to produce bread and cookies samples which were analyzed for the proximate composition, mineral content, physical properties, microbial quality and sensory properties. The functional properties of flour samples ranged from 0.80 to 1.43 g/ml, 1.91 to 2.31 g/ml, 1.88 to 1.98 g/ml, 1.23 to 1.57, 51.07 to 60.39 ℃ and 1.08 to 1.39 min/sec for bulk density, oil absorption capacity, water absorption capacity, swelling index, gelatinization temperature and wettability respectively. The results obtained for the baked products revealed that the proximate composition ranged from 8.35 to 10.39%, 12.06 to 15.30%, 3.27 to 5.23%, 2.09 to 3.24%, 2.41 to 4.02%, 63.88 to 69.64% and 355.8 to 363.75 Kcal in bread, and from 8.79 to 10.34%, 10.89 to 13.29%, 3.11 to 9.69%, 1.32 to 1.66%, 1.07 to 3.29%, 63.37 to 73.28% and 364.65 to 393.47 Kcal in cookies for moisture content, crude protein, fat, crude fibre, ash, carbohydrate and energy value respectively. The mineral composition of bread and cookies increases with increased substitution of wheat flour with soybean flour and ranged from 40.23 to 55.22 mg/100g, 15.17 to 30.32 mg/100g, 30.22 to 50.44 mg/100g, 13.65 to 27.29 mg/100g and 6.77 to 8.49 mg/100g in bread and from 26.62 to 45.52 mg/100g, 40.05 to 50.75 mg/100g, 23.19 to 34.80 mg/100g, 18.21 to 26.07 mg/100g and 3.82 to 8.10 g/100g in cookies for calcium, phosphorus, magnesium, potassium and sodium respectively. For the bread samples, physical properties ranged from 250.91 to 320.15 g (weight), 168.02 to 244.88 cm3 (loaf volume), 0.52 to 0.96 cm3/g (specific volume) and 0.42 to 0.61 cm (oven spring). In the cookie samples, it ranged from 18.98 to 26.69 g (weight), 0.62 to 0.98 cm (thickness), 9.04 to 9.89 kg (break strength) and 5.08 to 5.33 cm (diameter). The total fungal count (TFC) of the bread and cookie samples were equal to the number of total viable microbial count observed and ranged from 0 to 5 cfu/g in bread and 3 to 24 cfu/g in cookies. No coliform growth was detected in any of the bread and cookie samples. In sensory attributes, appearance ranged from 5.40 to 7.55 and 6.45 to 7.10; taste from 4.40 to 7.50 and 6.05 to 8.30; texture from 5.6 to 7.30 and 5.80 to 7.15; aroma from 4.75 to 6.85 and 5.60 to 7.80; general acceptability from 5.20 to 7.75 and 6.65 to 7.85 in bread and cookie samples respectively. Although substitution of some proportion of the wheat flour with small proportions of soybean flour showed no significant difference (P>0.05) in acceptance, higher proportions of soybean flour reduced the acceptability. The results shows that partial substitution of wheat flour used in baking with soybean flour could improve the nutritional quality of bread and cookies while providing a cheap alternative to the mainly imported wheat flour.