Two environmentally friendly innovative extraction techniques - subcritical water (SWE) and microwave-assisted extraction (MAE) were applied for the extraction of phenolics from pomegranate peel. The impact of process conditions (SWE: temperature 100–220 °C, extraction time 5–30 min; MAE: solvent water and 50% ethanol, irradiation power 470 and 800 W) on the quality of extracts in terms of the content of total phenolics, total flavonoids, major phenolic constituents (gallic acid, ellagic acid, punicalin, punicalagin), as well as 5-hydroxymethylfurfural(HMF) amount was investigated. For SWE, temperature of 130 °C and 20 min extraction time were found optimal for obtaining high content of bioactive compounds and minimizing the yield of HMF. During MAE, phenolic compounds were effectively extracted by using lower microwave power and 50% ethanol. Comparing two techniques, MAE is more efficient than SWE for the extraction of phenolics from pomegranate peel while obtaining a HMF-free extracts.

中文翻译：

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亚临界水与微波辅助萃取技术对石榴皮酚类化合物及5-羟甲基糠醛含量影响的比较研究

应用亚临界水（SWE）和微波辅助萃取（MAE）两种环保创新提取技术从石榴皮中提取酚类物质。工艺条件（SWE：温度 100–220 °C，提取时间 5–30 min；MAE：溶剂水和 50% 乙醇，辐照功率 470 和 800 W）对提取物质量的影响（以总含量计）研究了酚类、总黄酮类、主要酚类成分（没食子酸、鞣花酸、安石榴苷、安石榴苷）以及 5-羟甲基糠醛 (HMF) 的量。对于 SWE，发现 130 °C 的温度和 20 分钟的提取时间最适合获得高含量的生物活性化合物并最大限度地减少 HMF 的产量。在 MAE 过程中，使用较低的微波功率和 50% 的乙醇可以有效地提取酚类化合物。