Determination of viability in dynamic in vitro gastrointestinal model and some probiotic properties of lactobacillus acidophilus used in manufacture of different dairy products

In this study, probiotic ice cream, probiotic yoghurt, probiotic cheese and acidophilus milk were manufactured by using Lactobacillus acidophilus HOWARU and L. acidophilus DSM 20079. Total solids (%), fat (%), ash (%) and protein (%) contents of probiotic ice cream, probiotic yoghurt, probiotic cheese and acidophilus milk samples were determined on the first day of the storage, the pH and titratable acidity values were determined on days 1, 15 and 30 of the storage. Probiotic ice cream, probiotic yogurt, probiotic cheese and acidophilus milk samples were passed through a dynamic gastointestinal model designed in laboratory conditions. Microbiological analyses were performed at total five points; probiotic ice cream, probiotic yogurt, probiotic cheese and acidophilus milk samples and four points at the dynamic gastrointestinal model as mouth, stomach and small intestine parts of the model, on days 1, 15 and 30 of the storage. Additionally, some in vitro probiotic properties of L. acidophilus HOWARU and L. acidophilus DSM 20079 strains isolated from the samples on days 1, 15 and 30 of the storage were determined. The pH values of probiotic ice cream, probiotic yogurt, probiotic cheese and acidophilus milk samples decreased and the titratable acidity values increased during the storage. During the storage and the passage through the dynamic in vitro gastrointestinal model, the mean counts of L. acidophilus in the probiotic ice cream, probiotic yogurt, probiotic cheese and acidophilus milk samples decreased. Moreover, the mean counts of Lactobacillus delbrueckii subsp. bulgaricus and Streptoccoccus thermophilus in the probiotc yogurt samples and the mean counts of total mesophilic aerobic bacteria and the bacteria growing in M17 in the probiotic cheese samples decreased during the storage and the passage through the dynamic in vitro gastrointestinal model. In the result of the study, the highest viability reduction of L. acidophilus was determined in probiotic yogurt sample followed by, respectively, acidophilus milk, probiotic cheese and probiotic ice cream The diameter of the inhibition zone values L. acidophilus isolated from probiotic ice cream, probiotic yogurt, probiotic cheese and acidophilus milk samples in order to determine the antimicrobial activity against to Escherichia coli and Bacillus cereus decreased during the storage. The antimicrobial activity of L. acidophilus isolated from different samples varied. Type of sample, the type of strain and the storage time had no effect on the resistance of L. acidophilus isolated from probiotic ice cream, probiotic yogurt, probiotic cheese and acidophilus milk samples against to amoxycillin-clavulanic acid, tetracycline, ampicillin, gentamicin, clindamycin and erhytromycin antibiotics . Adherence of L. acidophilus isolated from probiotic ice cream, probiotic yogurt, probiotic cheese and acidophilus milk samples to mucin-coated wells decreased during the storage. The adherence of L. acidophilus isolated from different samples to mucin-coated wells varied. To test the competitive adhesion ability, L. acidophilus was isolated from probiotic ice cream, probiotic yogurt, probiotic cheese and acidophilus milk samples, and the inhibition rate of E. coli adhered to mucin-coated wells by L. acidophilus isolated from the samples decreased during the storage. It was determined that the inhibition rate of E. coli adhered to mucin-coated wells by L. acidophilus isolated from different samples varied.