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 made by a complex and diverse consortium of microorganisms, predominantly wild yeasts and lactic acid bacteria (LAB), positioning it as a valuable source for the isolation of specific LAB strains. LAB are capable of synthesising metabolites known as exopolysaccharides (EPS) during fermentation which enhanced the quality of food product. The characteristics of exopolysaccharides which are produced by LAB vary greatly depending on structure, molecular size, and physicochemical properties. This study aims to determine the optimal conditions for EPS production and characterize the exopolysaccharide from Pediococcus pentosaceus SL4 isolated from Flacourtia inermis sourdough. The investigation utilized a modified de Man Sharpe Rogosa medium and response surface methodology (RSM). The screened factors included monosaccharide types and concentrations, inoculum size, agitation speeds, and fermentation time. Using the Box Behnken design, the optimized conditions for EPS production were sucrose concentration of 5%, inoculum size of 6%, and agitation at 100 rpm, resulting in a maximum yield of 426.2 mg/L after 24 h incubation. The partially purified EPS had a molecular weight of 7.35×10 ⁵ kDa with a degradation temperature of 91.8⁰C. The irregular, porous, and spongy morphology of EPS was observed by scanning electron microscopy. The EPS exhibited physiological properties such as water solubility index, holding capacity, and emulsifying activity. Overall, EPS exhibits technological properties as a stabilizer in the food industry.