Extraction of antioxidant pectic-polysaccharide from mangosteen (Garcinia mangostana) rind: Optimization using response surface methodology

Box-Behnken design (BBD) was employed to optimize the incubator temperature (X1: 50–80 °C), extraction time (X2: 2–4 h) and pH (X3: 2–4) to obtain a high antioxidant pectic-polysaccharide yield with high uronic acid content and antioxidant activity from mangosteen rind. Analysis of variance showed that the contribution of quadratic model was significant for the extraction yield and antioxidant activity whereas linear model was significant for pectin content. Optimization study using response surface methodology was performed and 3D response surfaces were plotted from the mathematical model. Two optimal conditions were given: condition (1) X1 = 80.0 °C; X2 = 3.93 h; X3 = 2.45, and condition (2) X1 = 67.7 °C; X2 = 3.67 h; X3 = 2.00. These optimum conditions yielded pectic-polysaccharide of ∼12.0–12.4%, uronic acid content of ∼20.2–21.1 mg/g, and %DPPHsc/g extract of 225–252, respectively. Close agreement between experimental and predicted values was found. This could therefore be applied in extraction of mangosteen-derived functional pectic-polysaccharide in industry.