[Optimal extraction of polysaccharide from Dioscorea nipponica by central composite design and response surface methodology].

OBJECTIVE: To optimize the extracting technology for polysaccharides from Dioscorea nipponica by response surface methodology. METHODS: The independent variables were extraction temperature, reflux time and liquid-to-solid ratio, the dependent variable was extraction rate of polysaccharides in Dioscorea nipponica. Linear or nonlinear mathematic models were used to estimate the relationship between independent and dependent variables. Central composite design and response surface methodology were used to optimize the process of extraction. The prediction was carried out through comparing the observed and predicted values. RESULTS: The optimum technological parameters were as follows: extraction temperature 91.5° C, reflux time 172.9 min, solid-to-liquid ratio 25.8:1 and 2 times for extraction. Bias between observed and predicted of rates was 1.3%. CONCLUSION: The extraction technology is simple, reliable and highly predictive.