Response Surface Optimization of Extraction Technology of Procyanidins from Buckwheat Shells

Procyanidins in buckwheat shells was extracted with a mixture of 70% ethanol and water.In order to maximize the extraction of procyanidins,a rotatable orthogonal central composite design combined with response surface and ridge analyses was employed.Extraction temperature and time affected the yield of procyanidins significantly(P 0.05),while the effect of ratio of material to liquid was not significant.The optimum extraction conditions were as follows:ratio of material to liquid 1:16.9,temperature 73 ℃,and extraction time 118.9 min.Under these conditions,the actual yield of procyanidins was 0.56%,which accounts for 94.9% of the theoretically predicted value of 0.59%.