Optimization of ultrasonic extraction of polysaccharides from dried longan pulp using response surface methodology

Ultrasonic technology was applied for polysaccharides extraction from the dried longan pulp and response surface methodology (RSM) was used to optimize the effects of processing parameters on polysaccharides yields. Three independent variables were ultrasonic power (X1), extraction time (X2) and ratio of water to raw material (X3), respectively. The statistical analysis indicated that three variables and the quadratic of X1 and X2 had significant effects on the yields, and followed by the significant interaction effects between the variables of X2 and X3 (p < .05). A mathematical model with high determination coefficient was gained and could be employed to optimize polysaccharides extraction. The optimal extraction conditions of polysaccharides were determined as follows: Ultrasonic power 680 W, extraction time 4.5 min, ratio of water to raw material 25 mL/g. Under these conditions, the experimental yield of polysaccharides was 4.455 ± 0.093%, which was agreed closely with the predicted value (4.469%).