COMPARATIVE EVALUATION OF YOGHURT SAMPLES FROM GOATS AND COWS MILK AND COMMERCIAL RETAIL OUTLET

Résumé

This paper compared the chemical (Proximate and mineral), acidity, microbial count and organoleptic properties of yoghurt samples produced from Nigeria locally bred goat and cow milk with commercially retail yoghurt during 14days of refrigerated storage. Yoghurt production was conducted by inoculation of the milk samples at 43^oC for 6hrs with 2% of streptococcus thermophillus and lactobacillus bulgarus active culture. The total ash content of yoghurt ranges from 0.23g/100g in the commercial yoghurt sample to 0.84g/100g in yoghurt from goat  milk which is considered significantly higher than that observed for yoghurt from cow milk. The commercially retail yoghurt had a significantly higher (P < 0.05) total solid matter than yoghurt from goat and cow milk. Calcium and phosphorus contents were significantly (P < 0.05) lowest in the commercial yoghurt (0.28%) to a significant higher value of 0.28% in goat milk. A statisitically significant drop in pH values was observed in the commercial yoghurt sample after one and two week storage compared to yoghurt from goat and cow milk. High lactic acid bacteria were observed in yoghurt from cow milk with lactococci group being higher than the lactobacilli group throughout the storage period. The yeast count range from a significant low (P < 05) value of 2.22 cfu/ml^-1 in commercial yoghurt sample to 3.22 and 3.24 in goat and cow milk respectively on day zero of storage. By the 7days of storage, the commercially retail yoghurt was significant (P < 0.05) least desirable with respect to colour, taste and overall acceptability while there was no significant difference in the consistency of all the yoghurt samples.