Optimization of the extraction of total flavonoids from Walnut shell using response surface methodology

In this paper,the optimum conditions for the extraction of total flavonoids from Walnut shell were determined using response surface methodology. On the basis of single-factor experiments,selecting extraction temperature,ethanol concentration and liquid-to-solid ratio as independent variables,response surface methodology was applied to investigate the effect of three variables on extraction yield of total flavonoids. A regression model describing extraction content of total flavonoids as a function of these three variables was established. The optimal conditions for achieving the high extraction rate of total flavonoids from Walnut shell were ethanol concentration of 59%,extraction temperature of 78℃ and liquid-to-solid ratio of 33:1. The result of verification experiment was coincided with predictive value,the content of total flavonoids from Walnut shell was 3. 61mg·g-1.