# Postbiotic Potential of Lactic Acid Bacteria Strains in Functional Minimally Processed Oranges
## 3 Results and Discussion
### Evaluation of Functional Traits of Isolates  
The strains were evaluated for their pro-technological aspects, such as their acidifying capacity, growth at different stresses (pH and temperature), and organic acid production. Regarding the acidifying test, all strains showed good acidifying properties (Figure 2). The highest acidifying activity was detected after 24 h for AS1 and AS3 _L. plantarum_ strains, reaching pH values of 3.83 and 3.77, respectively. This result may be attributed to the high concentration of organic acids, mainly lactic acid (Figure 3). Indeed, while the concentration of acetic and citric acid was found to be similar among the tested strains, the concentration of lactic acid was significantly different between _L. plantarum_ and _Ln. mesenteroides_ strains, reaching concentrations of 13.76 g/L and 13.69 g/L in AS1 and AS3 and 6.25 g/L and 5.31 g/L in MEL1 and MAC1, respectively. The type and level of organic acids produced are linked to the microbial species, the culture medium composition, and the growing conditions [21,22]. In addition, the different productions of organic acids, especially of lactic acid, are related to the metabolic pathway of LAB and whether it belongs to the homo- or heteroformterative group. As reported by [PERSON] and coworkers [8], _Leuconostoc_, _Pediococcus_, _Oneococcus_, _Weisella_, and _Lactibacillus_ genera induce the production of lactic acid isomers (D-, L-, or the racemic mixture) in relation to several factors, such as the growth phase, presence of specific substrates, nutrients, and oxygen. The generation time and lag phase are strongly influenced by the pH and temperature [23]. Therefore, the ability of the selected strains to tolerate different pH values (3.0 and 4.0) and their ability to grow at low temperatures (4 and 8 \({}^{\circ}\)C) (Figure 4) were tested. Figure 3: Organic acids detected through HPLC analysis. Figure 2: The acidification capacity of the LAB isolates tested. Several studies focused on _L. plantarum_ species have already confirmed their high versatility, adaptability, and tolerance to acidic environments and different temperature values [24]. In this study, both _L. plantarum_ strains showed a good resistance to both the tested pH and temperatures, highlighting a greater susceptibility for the lowest tested values (pH 3.0 and 4 \({}^{\circ}\)C). Specifically, concerning a pH of 3.0, the strains showed a stable cell density reaching the highest value after 8 h of incubation, reaching a density of 8.02 and 8.00 Log CFU/mL, respectively. A different trend was observed at a pH of 4.0, where both strains reached the highest cell density after 24 h of incubation, with values of 9.30 Log CFU/mL and 9.0 Log CFU/mL for AS1 and AS3, respectively. A similar trend was observed for the lowest tested temperature. Indeed, whereas AS1 showed a slight increase up to 24 h of incubation, a decrease in the cell density of AS3 was observed, reaching a value of 6.26 Log CFU/mL. On the contrary, an increase in viable cells at 8 \({}^{\circ}\)C was observed with a cell density of 10.5 Log CFU/mL and 10.0 Log CFU/mL after 48 h of incubation. Regarding _Ln. mesenteroides_ (MEL1 and MAC1), the results showed that both strains were affected by the lowest tested pH value. A good adaptation was observed at a pH of 4.0, where an increase in cell density was observed, with values of 9.23 Log CFU/mL and 9.40 Log CFU/mL for MEL1 and MAC1, respectively. Regarding the effect of temperature, the cell density remains quite constant at the lowest tested temperature, while the cell density increased with the highest temperatures for both _Ln. mesenteroides_ strains, reaching values of 9.90 and 8.06 Log CFU/mL after 48 h at 8 \({}^{\circ}\)C, respectively. Physico-Chemical Analyses of Minimally Processed Orange Slices Treated Differently During Refrigerated Storage  
During storage at refrigerated conditions (after 3, 8, and 10 days), physico-chemical analyses were performed.