Characterization of Highly Branched Dextran VB113 Produced by Leuconostoc mesenteroides VB113 as Traditional Pickle Isolate

Lactic Acid Bacteria (LAB) from traditional fermented foods serve as a promising source of novel exopolysaccharides (EPSs) with desirable techno-functional properties. In this study, the EPS production ability of LAB strains from traditional pickles was tested and a strong slimy isolate grown in a sucrose-rich environment was further selected. The isolate was identified as Leuconostoc mesenteroides VB113 and its EPS production characteristics were determined. HPLC analysis revealed that glucose was the only monomer in the EPS repeating structure, whereas ¹H and ¹³C NMR spectroscopy analysis demonstrated a branched dextran structure with 20% (1 → 3)-linked α-D-glucose units. Dextran VB113 showed a molecular weight of 2.4 × 10⁶ Da tested by GPC analysis. The functional groups within dextran VB113 were determined by FTIR analysis, and XRD analysis demonstrated its amorphous physical status. TGA and DSC analysis were applied for thermal characterization and a degradation temperature of 272.25 °C was observed for dextran VB113, suggesting its high thermal resistance. The micro-structural features of dextran VB113 were tested by SEM and AFM analysis that revealed spherical and fibrillary properties, respectively. These findings revealed the importance of testing different niches to obtain novel EPS-producing LAB strains that can be further evaluated to enhance the techno-functional properties of food systems. The branched nature of dextran VB113, together with its molecular weight and thermal characteristics, offers practical advantages for its potential usage as a thermal-stable thickening agent, emulsion stabilizer, and fat replacer in high-temperature food processing applications, such as bakery products, processed dairy, and plant-based meat analogs.