## 3 Results and Discussion
### Storage Stability in Skinmed Milk  
In order to test the viability of _S. thermophilus_ cells inside capsules during prolonged storage, we maintained them in skimmed milk at refrigeration conditions (4 \({}^{\circ}\)C) for 21 days (Figure 2). At the end of the period, cell viability showed 0.46, 1.62, 1.79, and 1.97 log decrease for _S. thermophilus_ TH982 cells encapsulated with S + G, S + F, S, and S + I, respectively. Capsules containing G as a co-encapsulating agent showed a better performance after 21 days with respect to other co-encapsulating agents. However, data show that free cells had the highest viability level throughout the storage period since there was no significant difference between initial (8.90 \(\pm\) 0.08 log CFU/mL; day0) and final (8.94 \(\pm\) 0.05 log CFU/mL; day21) values. Interestingly, S, S + I, and S + F capsules revealed a similar, not significantly different, viability reduction (_p_ < 0.05). Unlike some studies that indicate an increase in survivability during refrigerated storage conditions, which could be linked to the difference in species/strain used. _S. thermophilus_ is frequently used in the production of different dairy products, and it is highly adapted to the dairy environment. It was reported that encapsulation improved the stability of _L. plantarum_ during storage [33], and encapsulation of bacteria in alginate was found to improve survivability when compared to unprotected cell counts stored in skimmed milk for 24 h [14]. Since FAO and the International Dairy Federation (IDF) recommend that the minimum content of probiotic cells should be 10\({}^{7}\) CFU/g of product at the time of consumption [34], the four encapsulating agents used in this study were efficient in maintaining the required viability of _S. thermophilus_ TH982 after refrigerated storage in skimmed milk. The high numbers suggested by IDF have been proposed to compensate for the possible numerical reduction of probiotic organisms during passage through the human stomach and intestine. The cells must remain viable throughout the projected shelf-life period of a product so that when consumed, the product contains a sufficient number of viable cells. \begin{table}
\begin{tabular}{c c c c} \hline
**Capsule Composition** & **Cell in the Encapsulation Solution** & **Cells after Encapsulation** & **Encapsulation Efficiency** \\  & **(log CFU/mL)** & **(log CFU/g)** & **(EE\%)** \\ \hline Sodium alginate & 9.46 \(\pm\) 0.04 \({}^{\circ}\) & 8.61 \(\pm\) 0.19 \({}^{\circ}\) & 91.07 \({}^{\circ}\) \\ Sodium alginate + Inulin & 9.17 \(\pm\) 0.21 \({}^{\circ}\) & 9.04 \(\pm\) 0.12 \({}^{\circ}\) & 98.61 \({}^{\circ}\) \\ Sodium alginate + Gelatin & 9.39 \(\pm\) 0.09 \({}^{\circ}\) & 8.50 \(\pm\) 0.04 \({}^{\circ}\) & 90.50 \({}^{\circ}\) \\ Sodium alginate + Fucosyllactose & 9.34 \(\pm\) 0.03 \({}^{\circ}\) & 8.97 \(\pm\) 0.07 \({}^{\circ}\) & 96.13 \({}^{\circ}\) \\ \hline \end{tabular} Values are the mean \(\pm\) standard deviation (SD) of triplicate experiments (n = 3). Superscript letters in each column indicate statistically significant (_p_ < 0.05) differences among different formulations.  
\end{table} 
Table 1: Encapsulation efficiency (EE%) of _S. thermophilus_ TH982 using different encapsulating matrices. The viability of probioticotic bacteria in food products is affected by many intrinsic and extrinsic aspects such as dissolved oxygen and oxygen permeation through the package, post acidification in fermented products (lactic and acetic acids), pH, storage and incubation temperature, duration of fermentation, production of hydrogen peroxide due to bacterial metabolism, and processing conditions [35; 36]. Moreover, the specific strains used, the interaction between species, availability of nutrients, and growth promoters and inhibitors can affect viable cells' survivability [14]. The great survivability of free _S. thermophilus_ TH982 cells in skimmed milk is probably due to the fact that _S.