# Postbiotic Potential of Lactic Acid Bacteria Strains in Functional Minimally Processed Oranges
## 3 Results and Discussion
### Evaluation of Functional Traits of Isolates

Table 1: Colour and texture coordinates of orange slice samples treated differently during refrigerated storage. Figure 5: Weight loss (%) in orange slice samples treated differently during storage at refrigerated conditions. The pH value of the initial fresh oranges was 3.77, while in treated samples, it slightly varied between 3.45 and 4.00 (time 10 and time 3, respectively). No significance was found for total soluble solids during the first two times of refrigeration (times 3 and 8). Overall, the value of the TTS decreased in most samples, indicating that the treatment with pathogenic bacteria generally leads to a reduction in the TSS related to an increased consumption of available sugars. A significance was detected exclusively at time 10, showing the highest value around 12\({}^{\circ}\)Brix in the control, _E. coli, P. aeruginosa_, and _P. aeruginosa_ with CFSs. Overall, zooming in on the phenol content, it is interesting to highlight that samples treated with the CFS alone showed a significantly higher value than the controls, showing a phenol content of 779.09 mg/L. These results agree with those reported by [PERSON] and coworkers [26], who established the antioxidant activity of the CFS produced by LAB. The authors demonstrated how the application of the CFS obtained from LAB and, in particular, from _Pediococcus acidilactici_ in food packaging increased the antioxidant properties and inhibited the growth of pathogenic microorganisms, such as _S. aureus_ and _L. monocytogenes_. For the physical analysis (Table 1), the colour and texture showed only a slight variation between treated and control samples at any storage time. For the colour coordinates L* and b*, despite the statistical differences, no evident trend was detected between the different treatments and analysis time. For the a* coordinate (red to green indicator), a significant difference can be seen after 8 days of refrigeration, with a general value reduction in almost all samples at time 10 (from \(-5.12\) to \(-3.10\) for _Listeria_+CFS and _S. aureus_ samples, respectively). Regarding the firmness of the orange slices, there was no significant difference among the samples after 3 and 8 days of storage. A slight difference was found only at the last sampling point (with a firmness ranging from 1.59 N for _P. aeruginosa_ sample to 3.43 for _L. innocua_+CFS one), confirming that the consistency is not only related to the weight loss and the metabolism of the inoculated microorganisms [16]. Zooming in on the acid content, citric and lactic acids were the most prevalent compounds detected in all tested samples (Figure 6). In detail, regarding citric acid, there was an increase in CFSs and _E. coli_ and _P. aeruginosa_ samples with and without CFSs, reaching values between 11 and 12 g/L. The citric acid content is related to the matrix, exhibiting values similar to those reported by [PERSON] et al. [27], as 9.7 and 15.1 g/L, and to the microbial metabolism, storage temperature, and transcription factors involved [28]. As far as lactic acid is concerned, the starting value was  
Figure 6: Organic acids expressed as mg/L: (**A**) citric acid and (**B**) lactic acid. Data are expressed as mean (n = 3). found to be between 0.8 and 1.5 g/L in all samples and remained slightly constant over time, with values between 0.9 and 1.6 g/L at the end of storage, with the lowest value in _S. aureus_ and the highest in CFS samples, respectively. Dynamics of the Main Microbial Groups in Minimally Processed Orange Slices Treated Differently During Storage at Refrigerated Conditions  
Several pathogens are associated with the contamination of fresh fruit, such as _E. coli, Listeria_ spp., _Pseudomonas_ spp., and _S. aureus_[29]. Therefore, any proposal for new strategies must consider these microbiological risks to comply with hygienic parameters. In this scenario, the antagonistic effect of mixed CFSs, obtained from _L. plantarum_ spp. and _Ln. mesenteroides_, was evaluated at different storage times (Figure 7).