During this study, it was found that orange, lemon and tomato juices have a vital role in simulating lactic acid bacteria to produce lactic acid when they were used in yogurt production. The addition of juices to the milk used in yogurt production led to increase acidity in yogurt produced . The Acidity percentage in comparative sample of yogurt produced from cow's milk 0.75% and became 0.78 and 0.84 % with the addition of 3% and 10% orange juice respectively. However, the pH was less affective by using tomato juice than orange and lemon juices, where their pH were 4.45 , 4.30 and 3.98 respectively, and the juice was added in ratio of 3% to the cow's milk. This observation was encountered with buffalo's butter milk . The percentage of fat ,protien total solid decreased with the addation of juciesto them , while the yoghurt proccesed from buffalo milk was different significantly hn the syneresis and curd tention with the yoghurt proccesed from cows milk. The degree of the curd tention and the syneresis in buffalo yoghurt was 30g , 10ml/100ml respectively while it was 22g , 7ml /100ml in cows yoghurt.
Further, total count bacteria was an excess of 200*104 cfu/gm in all yogurt samples of both cow's and buffalo's butter milk with the addition of juices in the ratios of 3% , 5% and 10% . This bacteria count was higher than lactic acid bacteria present in comparative samples of which can be attributed to the increase of the microorganism activity and counts which caused acidity development as a response to the addition of these juices. total count bacteria of samples using lemon juice (5%) was reduced in cow's milk and buffalo's butter milk yogurt as 171*104 and 183*104 cfu/gm respectively.
Regarding the sensory evaluation tables, it was observed that the use of orange and lemon juices acquired the taste and flavor to the yogurt produced, while tomato juice caused to reduced sensory evaluation data of yogurt produced.