Abstract

A microwave-assisted extraction (MAE) technology developed to extract polyphenols from the strawberry leaves was optimized by response surface methodology (RSM). Box–Behnken design (BBD) with four-factor and three-level was used to estimate the effects of extraction time, microwave power, ethanol concentration, and liquid–solid ratio in strawberry leaf extracts on total phenolic content (TPC) and antioxidant capacity (DPPH and FRAP). The optimized conditions were extraction time of 40 s, ethanol concentration of 51.1%, microwave power of 300 W, and liquid–solid ratio of 61.6 mL/g. The TPC, inhibition percentage of DPPH radical, and FRAP were 89.21 mg GAE/g, 79.80%, and 34.62 mM FE/g under optimal conditions. The absolute errors between the experimental and predicted values were less than 5.00%, revealing that the model was fitted well. High Performance Liquid Chromatography (HPLC) analysis demonstrated that the major antioxidant polyphenols with the highest concentration extracted at the optimum conditions were sinapic acid and rutin. This study proves that the MAE technique can efficiently extract polyphenols with high antioxidant activity from strawberry leaves.

摘要

通过响应面法（RSM）优化了开发用于从草莓叶中提取多酚的微波辅助提取（MAE）技术。采用四因子和三水平的Box–Behnken设计（BBD）来估算草莓叶片提取物中的提取时间，微波功率，乙醇浓度和液固比对总酚含量（TPC）和抗氧化能力的影响（DPPH和FRAP）。优化的条件是提取时间为40 s，乙醇浓度为51.1％，微波功率为300 W，液固比为61.6 mL / g。在最佳条件下，TPC，DPPH自由基的抑制百分比和FRAP为89.21 mg GAE / g，79.80％和34.62 mM FE / g。实验值和预测值之间的绝对误差小于5.00％，表明模型拟合良好。高效液相色谱（HPLC）分析表明，在最佳条件下提取的最高浓度的主要抗氧化剂多酚是芥子酸和芦丁。这项研究证明，MAE技术可以有效地从草莓叶片中提取具有高抗氧化活性的多酚。