Optimization on production and technological properties of exopolysaccharide from Pediococcus pentosaceus SL4 isolated from sourdough Tomi-tomi (Flacourtia Inermis Roxb).

Sourdough is a fermented food produced by a complex and diverse consortium of microorganisms, predominantly wild yeasts and lactic acid bacteria (LAB), making it a valuable source for isolating functional LAB strains. During fermentation, LAB synthesize exopolysaccharides (EPS), which enhance the quality of food products. The characteristics of LAB-derived EPS vary widely depending on their structural features, molecular weight, and physicochemical properties. This study attempted to optimize EPS production and to characterize the exopolysaccharide produced by Pediococcus pentosaceus SL4 isolated from Flacourtia inermis sourdough. EPS production was optimized using a modified de Man, Rogosa, and Sharpe (MRS) medium and response surface methodology (RSM). The investigated factors included monosaccharide type (glucose, fructose, sucrose, galactose, and maltose) and concentration (25–125 g/L), inoculum size (2–10%), agitation speed (0–200 rpm), and fermentation time (8–56 h). Based on the Box–Behnken design, the optimal conditions for EPS production were a sucrose concentration of 5%, an inoculum size of 6%, and agitation at 100 rpm, resulting in a maximum EPS yield of 426.2 mg/L after 24 h of incubation. The partially purified EPS exhibited a molecular weight of 7.35 × 10⁵ Da and a degradation temperature of 91.8 °C. Scanning electron microscopy displayed an irregular, porous, and spongy morphology. The EPS demonstrated favorable techno-functional properties, including water solubility index, water-holding capacity, and emulsifying activity. Overall, the EPS produced by P. pentosaceus SL4 shows potential for application as a stabilizing agent in the food industry.