ABSTRACT

The research project was carried out to investigate the result of substitution of yoghurt with fermented tiger nut milk. The major objective of the study was to evaluate the nutritional quality of substitute milk products produced from tiger nut milk and its substitution in yoghurt while the specific objectives are: to produce milk extract from tiger nut milk, to produce yoghurt with cow milk and tiger nut milk and to determine the microbial, physicchemical, mineral composition and sensory analysis on the milk substitute developed from tiger nut milk yoghurt. The result of the physico-chemical composition, vitamin, microbial analysis and sensory properties of the complementary milk and the 100% tiger nut milk produced from the mixture of cow milk yoghurt plus tiger nut milk yoghurt and cow milk yoghurt without the addition of cow milk yoghurt respectively were evaluated. The result revealed that the complementary milk yoghurt samples 301 with 90.19% from the mixture of 60% of cow milk yoghurt plus 40% of tiger nut milk yoghurt gave a significant increase in their percentage of moisture content but sample 301 (100% tiger nut milk yoghurt) and 303 (80% cow milk yoghurt and 20% tiger nut milk yoghurt) with 4.15%, 11.2% and 20.08% respectively have significant increase in their percentage of crude protein, total solid, and percentage of carbohydrates. The pH value showed that all the complementary milk yoghurt samples ranging from 4.80 — 5.19 pH value and sample 301 (100% tiger nut milk yoghurt) with 4.92 pH value were significantly higher than sample 300 (100% cow milk yoghurt; control) with 4.78 pH value. This revealed that the 100% cow milk yoghurt was more acidic than the tigernut substituted milk yoghurt. The vitamin composition showed that the complementary milk yoghurt sample 306 (50% cow milk yoghurt and 50% tiger nut milk yoghurt) with 7.29p.g/loog had higher Vitamin A than 6.78 jig/i OOg of the control (100% of cow milk yoghurt), but the control with 1.58 jig/bOg had the highest Vitamin C. This indicated that the 100% cow milk yoghurt was richer in Vitamin C than Vitamin A over the complementary milk yoghurt. The result of the microbial analysis revealed that the complementary milk yoghurt ranging from 66.00 — 94.00 cfulmg revealed a lower microbial growth compared to the 98.00cflulmg at room temperature but showed no significant difference (P>0.05) at refrigeration temperature. The sensory evaluation showed that the complementary milk yoghurt samples ranging from 7.40 — 7.60 have equal general acceptability with that of the controls ranging from 7.95 — 8.10. Therefore, there was no significant difference (P>0.05) in the quality and acceptability of the milk yoghurt produced and those with 100% cow milk yoghurt alone and tiger nut milk yoghurt. This implies that the tiger nut milk could serve as a good substitute for manufacturing of nutritional base yoghurt since there is no significant difference in the general acceptability of the cow milk yoghurt and milk yoghurt.