Optimum conditions for the enzymatic hydrolysis of citron waste juice using response surface methodology (RSM)

This study investigated the optimum conditions, including pH, temperature, incubation time, and enzyme concentration, for the enzymatic manufacture of citron waste juice by pectinase and cellulase using response surface methodology (RSM). A central composite design was used as an experimental design for the allocation of treatment combination. The highest yield was 71.1% at pH 5.00, 51.15°C, 53.74 min, and 0.44%, whereas the lowest turbidity was 0.20 at pH 4.87, 50.21°C, 49.99 min, and 0.44%. The highest hunter’s L (lightness), a (redness), and b- (yellowness) values were 47.39 (pH 4.86, 50.72°C, 51.60 min, and 0.44%), −1.34 (pH 5.48, 49.36°C, 46.29 min, and 0.21%), and 13.18 (pH 5.49, 50.05°C, 43.31 min, and 0.23%), respectively. The highest electron donating activity was 68.36% at pH 4.51, 50.62°C, 47.00 min, and 0.23%. The highest limonin and nomilin contents were 3.49 mg/100 g (pH 4.51, 50.30°C, 48.34 min, and 0.21%) and 1.56 mg/100 g (pH 4.59, 50.08°C, 66.07 min, and 0.30%).