## 3 Results and Discussion
### Microbiological Quality and Biological Activity of Fermented OBB
Analysing the effect of the additive type (extract or lyophilate), it can be noticed that a significantly higher number of LAB was noted in samples with a 5% addition of chokeberry extract. Similarly to the oat beverages with chokeberry extracts and lyophilates, the samples with hawthorn demonstrated high microbiological quality since _E. coli, Enterobacteriaceae_ rods, and fungi were not observed. The number of LAB was initially at a level of 10\({}^{7}\)-10\({}^{8}\) CFU/mL; however, a significant increase was noted after 20 h of fermentation, which proves that both hawthorn extract and lyophilate have no inhibitory effect on LAB (Figure 6). After the fermentation process, the number of LAB in all variants of beverages with hawthorn additions was comparable (without statistically significant differences). The results of the microbiological analysis confirmed that the oat fermented beverage with hawthorn does not pose a health hazard to consumers. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Oat Beverages**} & \multicolumn{2}{c}{**Hawthorn Extract**} & \multicolumn{2}{c}{**Hawthorn Lyophiliate**} \\  & \multicolumn{2}{c}{**Fermentation Time**} & \\ \cline{2-5}  & **0 h** & **20 h** & **0 h** & **20 h** \\ \hline \hline \multicolumn{5}{c}{TPC (mg GAE/L)} \\ \hline Control & 84.93\({}^{\text{\text{BB}}}\) \(\pm\) 1.89 & 64.92\({}^{\text{\text{AL}}}\) \(\pm\) 3.50 & 84.93\({}^{\text{\text{BB}}}\) \(\pm\) 1.89 & 64.92\({}^{\text{\text{AL}}}\) \(\pm\) 3.50 \\
1\% addition & 239.39\({}^{\text{\text{DEF}}}\) \(\pm\) 5.90 & 251.88\({}^{\text{\text{dF}}}\) \(\pm\) 12.29 & 219.60\({}^{\text{\text{IDE}}}\) \(\pm\) 13.91 & 193.42\({}^{\text{\text{CC}}}\) \(\pm\) 5.27 \\
5\% addition & 243.65\({}^{\text{\text{dF}}}\) 15.50 & 199.73\({}^{\text{\text{CD}}}\) \(\pm\) 7.50 & 214.13\({}^{\text{\text{CD}}}\) \(\pm\) 9.39 & 215.41\({}^{\text{\text{AD}}}\) \(\pm\) 2.51 \\ \hline \multicolumn{5}{c}{Antioxidant activity (mM Trolox/L)} \\ \hline Control & 0.657\({}^{\text{\text{BBC}}}\) \(\pm\) 0.034 & 0.603\({}^{\text{\text{ABB}}}\) \(\pm\) 0.033 & 0.657\({}^{\text{\text{BBC}}}\) \(\pm\) 0.034 & 0.603\({}^{\text{\text{BAB}}}\) \(\pm\) 0.033 \\
1\% addition & 0.677\({}^{\text{\text{BCD}}}\) \(\pm\) 0.039 & 0.557\({}^{\text{\text{AL}}}\) \(\pm\) 0.026 & 0.808\({}^{\text{\text{EE}}}\) \(\pm\) 0.013 & 0.674\({}^{\text{\text{CDCD}}}\) \(\pm\) 0.020 \\
5\% addition & 0.743\({}^{\text{\text{CDE}}}\) \(\pm\) 0.032 & 0.543\({}^{\text{\text{AL}}}\) \(\pm\) 0.018 & 0.732\({}^{\text{\text{AD}}}\) \(\pm\) 0.011 & 0.532\({}^{\text{\text{AL}}}\) \(\pm\) 0.009 \\ \hline \hline \end{tabular}  
* Averages with different small letters (\({}^{\text{\text{AE}}}\)) are significantly different at \(p<0.05\) (comparison within a group of samples with the addition of extract and lyophilate separately). Averages with different capital letters (\({}^{\text{\text{AE}}}\)) are significantly different at \(p<0.05\) (comparison between groups of samples with the addition of extract and lyophilate).  
\end{table} 
Table 5: The effect of hawthorn extract and lyophilate addition on total polyphenol content and antioxidant activity of fermented oat beverages. During the OBB fermentation by _L. plantarum_ DKK 003, a decrease in pH value was observed for all tested samples. The measurements were conducted both at the beginning of the fermentation and after the process. The pH value of the control samples, without fortification, decreased from 5.08 \(\pm\) 0.05 to 4.15 \(\pm\) 0.03 after 20 h of fermentation. The same tendency was observed for all of the fortified OBB samples, independently of the used additive and its amount. For OBBs with black chokeberry extracts, the pH value decreased from 5.00 \(\pm\) 0.03 to 4.13 \(\pm\) 0.02 and, for the freeze-dried fruits, from 5.03 \(\pm\) 0.04 to 4.14 \(\pm\) 0.02 during the fermentation process. As for the hawthorn fortification of OBBs, the pH value of samples with added extract acidified from 5.04 \(\pm\) 0.04 to 4.14 \(\pm\) 0.01, and for the lyophilisates, from 5.03 \(\pm\) 0.04 to 4.14 \(\pm\) 0.02.