## 3 Results and Discussion
### Production of Enriched Fermented Milk Drink  
It is well-known that milk and fermented dairy produces do not contain polyphenols. Therefore, it would be useful to enrich them by utilizing sources of plant origin in order to improve their nutritional and functional values. Five different fermented milk drinks where prepared: (a) Sample 1 (S1)--no addition of FDE (Control); (b) Sample 2 (S2), containing the FDE of _M. germanica_ at 1.5% \(w/v\); (c) Sample 3 (S3), containing the FDE of _M. germanica_ at 3% \(w/v\); (d) Sample 4 (S4), containing the FDE of _C. azaroluus_ 1.5% \(w/v\); and (e) Sample 5 (S5), containing the FDE of _C. azaroluus_ of 3% \(w/v\). The fermented milk drinks were incubated at 40 \({}^{\circ}\)C until the pH reached 5-5.2. It took approximately 4 h to achieve the desired pH value in S1 (control, pH 6.25), while for the samples containing the FDE of _M. germanica_, namely, S2, with pH 6.1, and S3, with pH 5.9, times of 3.5 h and 2.5 h were required to achieve pH values of 5.19 \(\pm\) 0.02 and 5.14 \(\pm\) 0.05, respectively. The extracts S4, with pH 5.9, and S5, with pH 5.5, required times of 3 h and 1 h to obtain pH values of 5.20 \(\pm\) 0.01 and 5.12 \(\pm\) 0.01, respectively. The fermentation time was significantly shorter at all the concentrations of the milk drinks containing FDEs compared to the control. The main reason for this was the lower initial pH when the fruit FDE was added to the milk. Moreover, increasing the concentration of the FDE decreased the fermentation time. The viability of the lactic-acid-bacteria-population-fermented milk drinks during the 28 days of cold storage is shown in Figure 1. One day after production, the population of lactic acid bacteria varied significantly between samples within a range from 4.9 to 6.4 log\({}_{10}\) cfu/mL. During storage, the LAB population increased, which corresponds with other studies which observed that plant substances showed increased microbial populations [27]. On the last day of storage (Day 28), the population ranged between 7.3 and 7.4 log\({}_{10}\)(cfu/mL) in all the samples, without the values differing significantly. These results are in agreement with the Codex Alimentarius commission [28], which states that LAB counts added as a starter culture must be \(>\)10\({}^{6}\) cfu/mL. Figure 1: Lactic acid bacteria in enriched fermented milk drinks. Mean values with different letters. (a–c) were statistically different within the same day (\(p<\) 0.05). S = sample. As shown in Figure 2, the value of pH gradually decreased significantly during cold storage. The pH of all the samples, on the first day after production, had similar values of 4.91 \(\pm\) 0.01 to 5.18 \(\pm\) 0.01. The highest drop in pH was observed on day 14 for all the samples. Moreover, the amount of _M. germancia_ and _C. azarolus_ FDE extracts had no effect on the changes in pH during cold storage. At the end of cold storage, the pH of the fermented milk drinks ranged from 4.38 \(\pm\) 0.01 to 4.48 \(\pm\) 0.01. During the cold storage, no significant differences in pH values were observed between the fermented milk drinks containing FDE extracts and the control. This indicated that the FDE of both fruits had no effect on the post-acidification rate. Similar trends in pH changes during the cold storage of fermented dairy products were observed by other authors, who added plant/fruit extracts and inulin [4]. As for the contents of phenolic components and flavonoids and the antidiabetic capacity of the products, these were determined on the 1 st, 14 th and 28 th days of storage. The incorporation of the FDE of _M. germancia_ and _C. azarolus_ significantly increased both the TPC and TFC contents compared to the control fermented milk drink during the 28 days of cold storage, as shown in Figures 3 and 4. The increase in the TPC and TFC contents of the samples supplemented with FDE is due to the presence of plant-specific phytochemical compounds such as flavonoids and phenolic compounds.