Determination of Viability of Acid Adapted Bifidobacterium bifidum and Lactobacillus acidophilus Cultures in Yoghurt During Shelf Life

Yogurt is a functional nutrient with high nutritional value and is a suitable carrier for the intake of probiotics. The use of Bifidobacterium bifidum and Lactobacillus acidophilus cultures in the production of yoghurt production is becoming increasingly widespread. These products have been marketed named as probiotic yogurt samples in this study were produced by adding acid adapted and non-acid adapted L.acidophilus and B.bifidum in addition to the yoghurt culture. Yoghurt samples were stored at 4 ±1˚C for 21 days. Probiotic bacteria counts and pH and titration acidity values of the samples were examined on 1, 7, 14 and 21 day of the storage period. The results were analyzed comparatively and the differences in acid adaptation during 21-day storage time were evaluated. When the results of pH and titratable acidity of yoghurt samples are examined, it has been seen that in all samples the pH values decrease during storage and the titration acidity values increase in parallel with this results. Acid adaptation caused lower pH and higher titratable acidity values during atorage in the whole yoghurt samples that were produced by adding L.acidophilus, B.bififum and both cultures together. It was determined that the highest viable count in the yoghurt sample was found in yoghurt where L.acidophilus and B. bifidum cultures were used together. Acid adaptation caused an increase in the viability of L.acidophilus but not an increase in viability of B.bifidum. The acid environment adversely affectd B.bifidum. The number of viable probiotics in yogurt samples where two probiotic cultures were used together provided a value of 106 cfug which was critical for probiotic products at the end of the 21-day storage period. When the microbial counts are examined, promising values for the production of probiotic yoghurt have been obtain.

کلیدواژه ها:

Probiotic yoghurt ، functional yoghurt ، acid adaptation ، L.acidophilus ، B.bifidum