Production steps of fermented milk product containing Lactobacillus reuteri and Streptococcus thermophilus, determination of technological properties and aroma profiles

In this study, a new probiotic fermented milk product was produced by utilizing the synergistic effect of L. reuteri and S. thermophilus. The study was carried out in three parallels. Microbiological and physicochemical analyzes were applied to the samples of the new probiotic fermented milk product produced on the 1st, 3rd, 7th and 15th days. In addition, the aroma profile and organic acid content of the product samples were also examined. Prejudices against drug consumption restrict the consumption of dietary supplement tablets and capsules, which are used as drugs. Therefore, the consumption of probiotics can only be achieved by adding probiotic properties to the food by adding them to the starter cultures in products such as fermented milk products. Therefore, the aim of our study is to produce a new probiotic fermented milk product that can be used in human diets. According to the analysis results of the study, the pH of the product reached 4.6, which is the isoelectric point of casein, after 12 hours of incubation. The water activity was 0.985, the dry matter content was 10.58%, the oil rate was 3.6, and the protein value was 4.030. In microbiological analysis results, L. reuteri 109 cfu/ml, S. thermophilus 109 cfu/g yeast-mold count was <100 cfu/g. In the analysis of aroma profiles, the amount of acetic acid was determined as 10.56%, the ethanol value as 0.44%, and the value of 2-methylbutanal in the aldehyde group as 32.97%. As a result of the organic acid analysis, the lactic acid value of the product was 14.64 mg/g, the acetic acid value was 2.80 mg/g and the citric acid value was 0.64 mg/g. In the physicochemical analyzes performed during the storage of the new probiotic fermented milk product, the pH was 4.65, 4.86, 4.52 and 2.91, respectively, on the 1st, 3rd, 7th, and 15th days, and the fat ratio was (%) 3.6, 3, 6, 3.3 and 2.8 and protein values were determined as 4.030, 4.027, 4.023 and 4.015, respectively. In the results of microbiological analysis, the lactobacillus and streptococcal counts were found to be >109 cfu/g, and the yeast-mold count as <100 cfu/g during storage. These values show that the product can be consumed during the storage period of 15 days. As a result, the new probiotic fermented milk product that we produced as a result of our study meets the conditions for acceptance of probiotics in the Turkish Food Codex.