The foremost objective of this work is to assess the microcapsules composition (polymer-based and polymer/clay-based) effect, on the release of rosemary essential oil into w/o medium and evaluate their antioxidant activity. Calcium alginate (CA) and calcium alginate/montmorillonite hybrid (CA-MTN) microcapsules were developed following an ionotropic crosslinking gelation and were used as host materials for the encapsulation of rosemary essential oil. The unloaded/loaded CA and hybrid CA-MTN microcapsules were characterized by Fourier transform infra-red (FT-ATR) spectroscopy, thermal analysis (TGA), scanning electron microscopy (SEM) and DPPH assay. The evaluation of the microcapsule’s physicochemical properties has shown that the clay filling with montmorillonite improved the microcapsule’s properties. The encapsulation efficiency improved significantly in hybrid CA-MTN microcapsules and exhibited higher values ranging from 81 for CA to 83% for hybrid CA-MTN and a loading capacity of 71 for CA and 73% for hybrid CA-MTN, owing to the large adsorption capacity of the sodic clay. Moreover, the hybrid CA-MTN microcapsules showed a time-extended release of rosemary essential oil compared to CA microcapsules. Finally, the DPPH assay displayed a higher reduction of free radicals in hybrid CA-MNT-REO (12.8%) than CA-REO (10%) loaded microcapsules. These results proved that the clay–alginate combination provides microcapsules with enhanced properties compared to the polymer-based microcapsules.

This study aimed to characterize the fermentation of commercial xylooligosaccharide (XOS) using Lactiplantibacillus plantarum S61. XOS was utilized as the main carbon source in a modified MRS medium (MRSm) at concentrations of 1%, 2%, 4%, and 6% (w/v). The growth of L. plantarum S61 was tracked daily over a week and compared to a control MRS medium using glucose as the main carbon source. The pH, total free acidity, and biomass were analyzed during fermentation, and the resulting fermentation product was analyzed for its content of fatty acids, total polyphenols, and the production of antioxidant and antimicrobial metabolites. The findings revealed that L. plantarum S61 thrived in MRSm, particularly at a 6% XOS concentration, which was identified as the best condition among the four tested concentrations (1%, 2%, 4%, and 6%). The fermentation of XOS by L. plantarum S61 significantly increased the total phenolic content and antioxidant activity compared to glucose, with the highest phenolic content observed at 6% XOS (6.70 ± 0.01 mg GAE/g). The strains produced various organic acids including lactic, malic, and oxalic acids from glucose and XOS. Notably, the strains yielded a broader range of organic acids with higher contents in the presence of XOS, leading to enhanced antifungal and antibacterial activities compared to glucose. Significant antibacterial activity was observed against Gram-negative bacteria, particularly Salmonella enterica, with inhibition zones of 20.25 mm and 11.75 mm for XOS (5% and 6%) and glucose, respectively. For Gram-positive bacteria, S. aureus and M. luteus exhibited inhibition zones of 20.01 mm for XOS 6% and 10.25 mm for glucose. In terms of antifungal activity, the strongest inhibition was observed against Rhodotorula glutinis, with inhibition zones of 26.00 mm for XOS 6% and 20.04 mm for glucose. The fermentation product of XOS by L. plantarum S61 showed significant inhibitory effects against pathogenic bacteria and yeasts, suggesting its potential application in the manufacturing of preservatives with antifungal properties and pharmaceutical products targeting pathogenic and spoilage yeasts.