Optimization of enzymatic extraction technology of polysaccharide from Osmanthus fragrans using response surface methodology and investigation on its antioxidant activity

Objective:This study aimed to optimize the enzymatic extraction technology of polysaccharide from Osmanthus fragrans and investigate its antioxidant activity. Method:The response surface method (RSM) was adopted to establish the mathematical model, which used polysaccharides extraction rate as response value, and used the ratio of water to material, cellulase concentration, extraction temperature and extraction time as experimental factors to optimize the polysaccharide extraction conditions from Osmanthus fragrans. Antioxidant activity of polysaccharides was measured by DPPH and O2-·free radical elimination method. Result:The optimum conditions obtained by RSM were as follows, polysaccharide yield was most significantly affected by cellulase concentration, followed by extraction time, water to material ratio and extraction temperature. The concentration of cellulase was 6.0mg/m L, extraction time was 80 min, the ratio of water to feedstock was 8 ∶1m L/g, extraction temperature was 55℃. Under the optimal conditions, the predicted extraction rate by mathematical model was19.05%, while the experimental extraction rate was 18.43%, with a difference of less than 5%. IC50 of DPPH and O2-· were 0.846mg/m L and 1.256mg/m L, respectively. Antioxidant activity of sample polysaccharides was weaker than those of vitamin C. Conclusion:The optimum enzymatic extraction technology of the polysaccharides from Osmanthus fragrans by RSM was convenient and feasible, and the extracted polysaccharides had good antioxidant activity.