Effect of Adding Bifidobacreria and Turmeric on the Quality of Yoghurt

Effect of adding bifidobacteria and turmeric, on the quality of yoghurt monitors the survival of different strains of bifidobacteria and changes of chemical, microbiological and organoleptic properties during storage of yoghurt were investigated. Results indicated that yoghurt treatments which made with normal starter had higher acidity than those of corresponding treatments made with bifidobacteria strains. Titratable acidity decreased as the amount of B. bifidum ATCC 15696, B. bifidum ATCC 29521 and B. longumBL-04increased. Samples which made with incorporating bifidobacteria strains have a higher pH values than control sample. There was a positive correlation between the amount added of bifidobacteria and pH. Neither the strain nor the species of bifidobacteria significantly affected (p < 0.05) the total solids content of yoghurt. Diacetyl methyl carbinol content of all set yoghurt treatments increased gradually up to the sixth day of storage, then decreased as storage period progressed. No significant differences recorded among yoghurt treatments in total protein and fat content.Total bacterial counts of all yoghurt treatments increased up to the third day of storage then decreased up to the end of storage period. Incorporating of bifidobacteriacaused a significant decrease of the counts of moulds and yeasts. Even after 9 days of cold storage, the counts of bifidobacteria in all yoghurt treatments were still higher than the minimum level (10⁵ – 10⁶ / ml) that should be present at the consumption of the product to achieve the beneficial effect of bifidobacteria. Probiotic yoghurt treatments which made by adding B. bifidum ATCC 15696 were not significantly different (p > 0.05) of organoleptic properties from corresponding treatments made by adding either B. bifidum ATCC 29521 or B. longum BL-04. After 12 days of cold storage, the count of bifidobacteria with turmeric was still higher than the minimum level (10⁵ – 10⁶ / ml) that should be present at the consumption of the product. The turmeric concentration did not affect on the survival of bifidobacteria strains. Yoghurt treatments which made by adding bifidobacteria with turmeric slightly decreased organoleptic properties.