Effect of spearmint on the growth of Lactobacillus acidophilus and Bifidobacterium bifidum in probiotic milk and yoghurt

In the present study, the potential of producing foods containing probiotic bacteria with the bases of milk, yoghurt and spearmint was evaluated. The goal was to determine the effects of different doses of spearmint (0, 0.3, 0.6 and 0.9%) on the growth of two probiotic bacteria, that is, Bifidobacterium bifidum and Lactobacillus acidophilus, in milk and yoghurt produced in the first and second phases, respectively. The products were then examined in terms of pH, acidity and microbe counting during the incubator setting period and their respective permanence. In day 10, the production quantities of the products were evaluated by sensory method. The results of the questionnaires filled by 50 people in statistical–descriptive test were analyzed using SPSS software version 16 system. In the samples with either L. acidophilus or B. bifidum and the sample containing both bacteria, it was observed  that the increased concentration of spearmint did not create a favorable taste of yoghurt and of all the samples the yoghurt containing 0.3% spearmint and the testifier were with the best tastes. The increased concentration of spearmint had no effect on the yoghurt permanence and the yoghurt containing 0.3% spearmint, and the testifier containing 0% spearmint were of greater permanence than the other samples. The bioability of probiotic bacteria was measured by direct counting method. During the 15-day period, the number of bacteria decreased and no significant difference between the testifier sample and the samples containing different concentrations of spearmint was observed. Duration of the product permanence was determined within the same period. Upon examination of the results, it was revealed that the increased concentration of spearmint had a positive effect on the growth of the probiotic bacteria, L. acidophilus and B. bifidum in probiotic milk and yoghurt. Key words: Probiotic, Bifidobacterium bifidum, Lactobacillus acidophilus, spearmint.