A central composite rotatable design (CCRD) was used to evaluate the effects of extraction time, extraction temperature, particle size of mulberry leaf, number of extraction and water to the mulberry leaf ratio on extraction yield of mulberry leaf crude polysaccharides (MLCP). The response surface methodology (RSM) showed that the significant quadratic regression equation with high R(2) (=0.9782) was successfully fitted for extraction yield of MLCP as function of independent variables. The overall optimum region was found to be at the combined level of extraction time 5h, extraction temperature 85 °C, particle size of mulberry leaf (mesh) 40, number of extraction 4 and water to mulberry leaf ratio 18. At this optimum point, extraction yield of MLCP was 12.0017±0.42%. No significant (p>0.05) difference was found between the actual and predicted (11.6286±0.19) values. The results demonstrated that MLCP had strong scavenging activities on DPPH and hydroxyl radicals. Overall, MLCP may have potential applications in the medical and food industries.
Keywords: Extraction; Mulberry; Optimization; Polysaccharides; RSM.
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