## 4 Discussion  
### Probiotic Bacterial Encapsulation as a Method of Protection from External Factors  
It is generally known that external factors such as temperature, light exposure, relative humidity and wall material composition influence bacteria viability during storage of probiotics-loaded formulations [45; 46]. Probiotic bacterial encapsulation may be an effective method of protecting the microorganisms against temperature, pH, UV light and other preservation systems. Probiotics are very temperature-sensitive, and their death rate increases with temperature and is particularly severe above 51 \({}^{\circ}\)C [47; 48]. In the case of the impact of high temperatures on the tested microcapsules, our results are consistent with the reports by other research groups [49]. As can be seen in Figure 1, even temperatures of 40 \({}^{\circ}\)C and 50 \({}^{\circ}\)C were not lethal to encapsulated _L. casei_, and cells encapsulated in carriers still showed significantly higher survival rates compared with non-encapsulated cells. Similarly, a high survival rate (90%) of the encapsulated _L. plantarum_ strain was previously reported when researchers heat-treated the microcapsules at 50 \({}^{\circ}\)C for 20 min [50]. In the study by [PERSON] et al. [51], it was found that encapsulated bacteria survived significantly better (\(p<0.05\)) than free cells when exposed to temperatures of 55, 60 and 65 \({}^{\circ}\)C. After exposure to heat at 65 \({}^{\circ}\)C for 30 min, the reduction in _L. rhamn_ encapsulated in alginate and chitosan microspheres decreased by only 2.55 log, while the number of free cells decreased by approximately 5 log [51]. In our case, the developed alginate carriers ensure the isolation of probiotictic strains (_L. casei_) due to the action of acidic and alkaline environments (pH = 2, 5.5 and 9). Moreover, in the case of microsphere samples 2 and 3, there were no significant differences in cell viability among different incubation times. However, in the case of the extreme pH \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{3}{*}{**Sample No.**} & \multicolumn{2}{c}{**Immediately after**} & \multicolumn{2}{c}{**After 7 Days**} & \multicolumn{2}{c}{**After 30 Days**} & \multicolumn{2}{c}{**After 120 Days**} \\  & \multicolumn{2}{c}{**Preparation**} & & & & & & & \\ \cline{2-9}  & **Cell** & **Cell** & **Cell** & **Cell** & **Cell** & **Cell** & **Cell** \\  & **Viability *** & **Log** & **Viability** & **Log** & **Viability** & **Log** & **Viability** & **Log** \\  & **[log CFU/g]** & & **[log CFU/g]** & & **[log CFU/g]** & & **[log CFU/g]** & & **[log CFU/g]** & \\ \hline E2 & 10.74 \(\pm\) 0.9 & 0.86 & 6.63 \(\pm\) 0.5 & 4.97 & 4.8 \(\pm\) 0.8 & 6.8 & 0 & 11.6 \\ E3 & 8.51 \(\pm\) 1.2 & 2.03 & 6.55 \(\pm\) 0.4 & 3.99 & 6.25 \(\pm\) 0.3 & 4.29 & 6.13 \(\pm\) 0.9 & 4.41 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Viability of probiotictic bacteria (_Lactobacillus casei_) in cosmetic formulations. values of 2 and 9, after 60 min, there was the almost complete elimination of bacterial cells, while the use of microencapsulation increased the viability of the probiotic strain. These findings are consistent with those of other research groups [49; 51; 52]. In the study by [PERSON] et al. [49], it was shown that encapsulated _L. rhamnus_ exhibited higher viability at different pH values in comparison with the non-encapsulated group. Consistent with previous reports by [PERSON] et al. on the encapsulation of _L. acidophilus_, at pH = 1.2, the non-encapsulated strain was completely destroyed after 1 h of incubation, while the encapsulated cells maintained viability above 10\({}^{6}\) log CFU/mL at pH = 1.5 after 2 h [53]. Also, in the study by [PERSON] et al., it was found that non-encapsulated _Lactobacillus plantarum_ 15 HN was very sensitive to low-pH conditions and its viability was dramatically lost (from 9.76 \(\pm\) 0.06 log CFU/g to 3.63 \(\pm\) 0.03 log CFU/g), while the survival rate was approximately 37%.