In this study, the effects of microwave-assisted extraction conditions on antioxidant capacity of sweet tea (Lithocarpus polystachyus Rehd.) were studied and the antioxidants in the extract were identified. The influences of ethanol concentration, solvent-to-sample ratio, microwave power, extraction temperature and extraction time on Trolox equivalent antioxidant capacity (TEAC) value, ferric reducing antioxidant power (FRAP) value and total phenolic content (TPC) were investigated by single-factor experiments. The response surface methodology (RSM) was used to study the interaction of three parameters which had significant influences on antioxidant capacity including ethanol concentration, solvent-to-sample ratio and extraction time. The optimal conditions for the extraction of antioxidants from sweet tea were found as follows—ethanol concentration of 58.43% (v/v), solvent-to-sample ratio of 35.39:1 mL/g, extraction time of 25.26 min, extraction temperature of 50 ℃ and microwave power of 600 W. The FRAP, TEAC and TPC values of the extract under the optimal conditions were 381.29 ± 4.42 μM Fe(II)/g dry weight (DW), 613.11 ± 9.32 μM Trolox/g DW and 135.94 ± 0.52 mg gallic acid equivalent (GAE)/g DW, respectively. In addition, the major antioxidant components in the extract were detected by high-performance liquid chromatography with diode array detection (HPLC-DAD), including phlorizin, phloretin and trilobatin. The crude extract could be used as food additives or developed into functional food for the prevention and management of oxidative stress-related diseases.

中文翻译：

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微波辅助提取条件对甜茶抗氧化能力的影响。

在这项研究中，微波辅助提取条件对甜茶（Lithocarpus polystachyus）抗氧化能力的影响Rehd。）进行了研究，并鉴定了提取物中的抗氧化剂。通过一次实验研究了乙醇浓度，溶剂-样品比，微波功率，萃取温度和萃取时间对Trolox当量抗氧化能力（TEAC）值，三氧化二铁抗还原能力（FRAP）值和总酚含量（TPC）的影响。因素实验。响应面法（RSM）用于研究三个参数的相互作用，这三个参数对抗氧化剂的能力有重大影响，包括乙醇浓度，溶剂与样品的比例和萃取时间。发现从甜茶中提取抗氧化剂的最佳条件如下：乙醇浓度为58.43％（v / v），溶剂与样品的比例为35.39：1 mL / g，提取时间为25.26分钟，提取温度为50℃，微波功率为600W。在最佳条件下，提取物的FRAP，TEAC和TPC值为381.29 Fe（II）/克干重（DW）为±4.42μM，Tlolox / g DW为613.11±9.32μMTrolox / g DW为135.94±0.52 mg没食子酸当量（GAE）/ g DW。此外，提取液中的主要抗氧化剂成分通过高效液相色谱-二极管阵列检测（HPLC-DAD）进行检测，其中包括phlorizin，phloretin和trilobatin。粗提物可用作食品添加剂或开发成功能食品，以预防和管理氧化应激相关疾病。