Production of probiotic grape juice

In this thesis study, grape juice samples of Lactobacillus fermentum CECT 5716 and Lactobacillus acidophilus DSM 20079 probiotic bacteria strains were stored at 4 oC for 21 days. Some physicochemical properties and probiotic bacteria viability levels of grape juice samples were followed on the 1 st, 7th, 14th and 21st days of storage. In the analyses conducted during the study, L. acidophilus and L. fermentum added to grape juice increased the viability levels until the 14th day of storage. After the 14th day, L. acidophilus decreased by 7.7% to 2x107 cfu /mL, while L. fermentum decreased by 7.6% to 1.6x107 cfu / mL. Both samples showed probiotic properties for 21 days by providing 106 cfu / mL standard for probiotic products to be effective. While the brix value of grape juice samples supplemented with L. acidophilus increased during storage, a decrease was observed in the brix values of L. fermentum added grape juice samples. When the pH values of all samples were examined, it was observed that it ranged between 3,64 and 3,42 (p>0.05). In the titration values, while the titration acidity% of the control sample remained constant during the storage, an increase was observed in the samples with probiotic bacteria. During the storage period of the study, the amount of phenolic matter increased by 12% in the control sample and by 15.26% in the grape juice sample to which L. fermentum was added. Although there was a loss of 14% in the grape juice sample to which L. acidophilus was added, it remained within the standard values. A statistically significant decrease was found in the viscosity and color values (L*, a*, b*) of all grape juice samples (p<0.05). Considering all quality parameters and vitality levels during 21 days of storage, the development of L. acidophilus and L. fermentum added grape juice drink is promising and its general findings show that grape juice is a suitable food matrix for probiotic bacteria. Key words: Functional drink, Probiotic, Grape juice, L. acidophilus, L. fermentum