Optimization of Extraction Process of Tannins from Almond Skin and Its DPPH Radical Scavenging Activity

The yield of almond skin tannins was served as indicator,and the four effects of factors on the extraction efficiency of almond skin tannins were investigated,such as solid to liquid ratio,extraction time,extraction temperature and volume fraction of ethanol. On the basis of single factor,response surface methodology was used to optimize the extraction process of almond skin tannins,and the DPPH radical scavenging activity of almond skin tannins was tested under the optimal process. The results showed that the extraction process model of almond skin tannins was highly significant. The optimum conditions were as follows:the ratio of solid to liquid was 1:22 (g/mL),the extraction time was 89 min,the extraction temperature was 70 ℃,and the volume fraction of ethanol was 50%. Under these conditions,the yield of almond skin tannins was 2.13%. When the concentration of almond skin tannins was 250 μg/mL,the DPPH radical scavenging rate reached 98.65%,which suggested that almond skin tannins had strong antioxidant activity.