Evaluation of phenolic and antioxidant properties of strawberry as a function of extraction conditions

Abstract We studied the extraction of antioxidant phenolic compounds, anthocyanins and the evaluation of antioxidant activity of strawberries in different extraction conditions, varying the type of solvent (ethanol:water (50%) and acetone:water (60%), the extraction time (15 and 60 min) and the solvent volume to sample mass ratio (5 mL/g and 20 mL/g). In addition, we performed principal component analysis and cluster analysis. The results showed that, although the two solvents tested had similar influence on total phenolic compounds extraction and antioxidant activity, the 60 minutes of extraction and the use of the solvent volume/sample mass ratio of 20 mL/g were the best extraction conditions, both for the 1st and 2nd recovered extracts. However, the solvent had a marked effect on anthocyanins’ extraction, so that acetone/water extracted almost the double as compared to ethanol/water, for the same extraction conditions. Finally, factor analysis allowed identifying a grouping structure of two components, which was confirmed by the dendogram obtained from cluster analysis.摘要 本研究针对不同提取条件下草莓中抗氧化酚类化合物（Antioxidant Phenolic Compounds）、花青素（Anthocyanins）的提取工艺及其抗氧化活性（Antioxidant Activity）开展探究，考察的变量包括溶剂类型（体积比50%的乙醇水溶液、体积比60%的丙酮水溶液）、提取时间（15 min与60 min）以及料液比（Solvent Volume to Sample Mass Ratio，5 mL/g与20 mL/g）。此外，本研究开展了主成分分析（Principal Component Analysis）与聚类分析（Cluster Analysis）。结果表明，尽管两种受试溶剂对总酚类化合物（Total Phenolic Compounds）提取率与抗氧化活性的影响相近，但针对两次回收的提取物而言，60 min的提取时长以及20 mL/g的料液比均为最优提取条件。然而，溶剂类型对花青素的提取效果具有显著影响：在相同提取条件下，丙酮-水体系的提取量几乎为乙醇-水体系的两倍。最后，因子分析（Factor Analysis）成功识别出包含两个主成分的分组结构，该结果通过聚类分析得到的树状图（Dendrogram）得到了验证。