Design of experiment approach for the process optimization of ultrasonic-assisted extraction of polysaccharide from mulberry leaves by response surface methodology

Mulberry is considered as food-medicine herb, with specific nutritional and medicinal values. In this study, response surface methodology (RSM) was employed to optimize the ultrasonic-assisted extraction of total polysaccharide from mulberry using Box-Behnken design (BBD). Based on single factor experiments, a three level, three variable central composite designs were carried out to establish a quadratic regression model for the extraction efficiency of total polysaccharides as a function of extraction time, extraction temperature and material-water ratio. The optimum extraction conditions were obtained as follows: extraction temperature of 70°C, material-water ratio of 1:30 (g/ml), and extraction time of 40 min. Under these conditions, the predicted total polysaccharides extraction efficiency was 3.6%, while the experimental value was 3.56%. Analysis of variance (ANOVA) was used to examine the statistical significance of the developed model. The result indicates that the established model well predicted the extraction efficiency of total polysaccharides from mulberry leaves. Key words: Mulberry leaves, total polysaccharides, extraction conditions, design of experiment.