RESUMEN
Yoghurt was manufactured from 6Kg of heat treated mixed cow's and buffalo's milk [1:1] with 2% Lactobacillus delbrueckil subsp. bulgaricus and Streptococcus salivarius subsp. thermophilus [1:1] as normal starter cultures of the 1[st] group. However, another two groups of yoghurt were inoculated with 1% normal starter culture with 1% Lb acidophilus culture for 2[nd] group and 1% Lb plantarum for the 3[rd] group. Yoghurt samples were analyzed for organoleptic scores, titratable acidity and microbiological quality during refrigerated storage till the signs of spoilage appeared. The trials repeated for processing and analysis for 3 times. The obtained results indicated that acidophilus yoghurt had the best organoleptic properties as compared with control and plantarum yoghurt samples and have better acidity and microbiological quality. Accordingly, the using of Lb acidophilus and Lb plantarum is very effective in prolonging the yoghurt shelf life up to 21 days of refrigerated storage with better properties than control yoghurt. As well as, they promote the consumer health as they are probiotic bacteria