ABSTRACT

Yoghurt samples were produced from blends ofskimmed cow milk, coconut milk and tigernut milk at different ratios by fermentation using starter cultures ofLactobacillus bulgaricus and Streptococcus thermophilus (1:1 w/w) at 28°C for 36 hours. The samples were analyzed for their proximate, physicochemical, vitamin, mineral, microbial and sensory qualities. The results obtained revealed that the proximate composition ranged from 75.03% to 76.48%, 6.02% to 7.28%, 0.02% to 0.11%, 9.08% to 14.44%, 0.80% to 0.97%, 3.15% to 7.80%, 142.52 Kcal to 166.64 Kcal for moisture, crude protein, crude fibre, fat, ash, carbohydrate and energy value respectively, whereas the physicochemical properties ranged from 5.06 to 5.51, 0.60% to 0.87%, 1.73% to 4.62%, 0.98 to 1.15, 13.41% to 16.25% and 14.28% to 17.13% for pH, total titratable acidity, lactose, specific gravity, total soluble solids (brix) and total solids respectively. The vitamin contents significantly increased with inclusion of coconut milk and tigemut milk, the values ranged from 67.33 lU/ml to 74.82 lU/ml for vitamin A, 4.92 mg/lOOml to 10.38 mg/ml for vitamin C and 0.08 mg/lOOml to 0.13 mg/lOOml for vitamin E. There was also increase in mineral content, with significant difference (P<0.05) being recorded among the samples and ranged from 293.84 mg/lOOml to 360.18 mg/lOOml, 203.07 mg/lOOml to 314.58 mg/lOOml, 563.06 mg/lOOml to 711.84 mg/lOOml and 0.40 mg/lOOml to 0.73 mg/lOOml for calcium, phosphorus, potassium and zinc respectively. For microbial analysis, total viable count ranged from 5.60 x 107 cfu/gto 1.04 x 108 cfu/g while total lactobacillus count ranged from 3.60 x 107 cfu/g to 9.10 x 107 cfu/g in the yoghurt samples. No fungal or coliform growth was observed in the samples. In terms of sensory attributes, appearance ranged from 6.00 to 7.55, mouthfeel from 5.20 to 6.90, taste 5.40 to 6.70, aroma 5.30 to 6.55 and general acceptability from 5.29 to 7.10, when evaluated on a 9 - point hedonic scale. There was generally no significant difference (P>0.05) in sensory properties among the samples especially those containing 100% and 85% of cow milk, indicating that the yoghurt samples with inclusion of coconut milk and tigernut milk could be equally acceptable to consumers. The resultrevealed that introduction of coconut milk and tigernut milk as partial substitute for skimmed milk could improve the nutrient quality of yoghurtABSTRACT

Yoghurt samples were produced from blends ofskimmed cow milk, coconut milk and tigernut milk at different ratios by fermentation using starter cultures ofLactobacillus bulgaricus and Streptococcus thermophilus (1:1 w/w) at 28°C for 36 hours. The samples were analyzed for their proximate, physicochemical, vitamin, mineral, microbial and sensory qualities. The results obtained revealed that the proximate composition ranged from 75.03% to 76.48%, 6.02% to 7.28%, 0.02% to 0.11%, 9.08% to 14.44%, 0.80% to 0.97%, 3.15% to 7.80%, 142.52 Kcal to 166.64 Kcal for moisture, crude protein, crude fibre, fat, ash, carbohydrate and energy value respectively, whereas the physicochemical properties ranged from 5.06 to 5.51, 0.60% to 0.87%, 1.73% to 4.62%, 0.98 to 1.15, 13.41% to 16.25% and 14.28% to 17.13% for pH, total titratable acidity, lactose, specific gravity, total soluble solids (brix) and total solids respectively. The vitamin contents significantly increased with inclusion of coconut milk and tigemut milk, the values ranged from 67.33 lU/ml to 74.82 lU/ml for vitamin A, 4.92 mg/lOOml to 10.38 mg/ml for vitamin C and 0.08 mg/lOOml to 0.13 mg/lOOml for vitamin E. There was also increase in mineral content, with significant difference (P<0.05) being recorded among the samples and ranged from 293.84 mg/lOOml to 360.18 mg/lOOml, 203.07 mg/lOOml to 314.58 mg/lOOml, 563.06 mg/lOOml to 711.84 mg/lOOml and 0.40 mg/lOOml to 0.73 mg/lOOml for calcium, phosphorus, potassium and zinc respectively. For microbial analysis, total viable count ranged from 5.60 x 107 cfu/gto 1.04 x 108 cfu/g while total lactobacillus count ranged from 3.60 x 107 cfu/g to 9.10 x 107 cfu/g in the yoghurt samples. No fungal or coliform growth was observed in the samples. In terms of sensory attributes, appearance ranged from 6.00 to 7.55, mouthfeel from 5.20 to 6.90, taste 5.40 to 6.70, aroma 5.30 to 6.55 and general acceptability from 5.29 to 7.10, when evaluated on a 9 - point hedonic scale. There was generally no significant difference (P>0.05) in sensory properties among the samples especially those containing 100% and 85% of cow milk, indicating that the yoghurt samples with inclusion of coconut milk and tigernut milk could be equally acceptable to consumers. The resultrevealed that introduction of coconut milk and tigernut milk as partial substitute for skimmed milk could improve the nutrient quality of yoghurt