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Pectin derived from plant waste sources is currently focused as an economical and eco-friendly approach. Optimization of pectin extraction from muskmelon peel by response surface methodology (RSM) was investigated in this study. Box–Behnken Design (BBD) was used to identify the optimal level of the extraction variables such as time, pH and temperature. A second-order model equation for pectin extraction was obtained from multiple regression analysis of experimental data with the correlation coefficient (R2) value of 0.92. ANOVA results showed that linear effect of temperature and combined effect of pH with temperature were found significant for pectin extraction from muskmelon peel. Validation results had good agreement with the predicted results. Pectin extracted from muskmelon peel was classed as high methoxy pectin with the equivalent weight of 384.5 g/mol. Non-newtonian pseudoplastic flow behaviour was observed for muskmelon pectin from the viscosity studies.

Statistical experimental designs were applied to optimize the fermentation medium for exopolysaccharide (EPS) production. Plackett–Burman design was applied to identify the significance of seven medium variables, in which sweet potato and yeast extract were found to be the significant variables for EPS production. Central composite design was applied to evaluate the optimum condition of the selected variables. Maximum EPS production of 9.3 g/L was obtained with the predicted optimal level of sweet potato 10 %, yeast extract 0.75 %, 5.5 pH, and time 100 h. The determined (R2) value was 0.97, indicating a good fitted model for EPS production. Results of this study showed that sweet potato can be utilized as a low-cost effective substrate for pullulan production in submerged fermentation.