The aim of this study was to evaluate the effects of different extraction parameters on total phenolic (TP) compounds and antioxidant activity (AA) from olive leaves (Olea europaea L.) using microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE) and maceration. The study also emphasized on the optimization of MAE and UAE conditions, and on the potential benefits of using MAE as a pretreatment to UAE. It was demonstrated that olive leaves were a good source of phenolic compounds with high antioxidant activity. MAE at a higher temperature (86 °C) was more efficient in terms of TP yield, with short extraction time (3 min). MAE performed with water as a solvent was effective in disrupting the olive leaf cells thereby promoting the release of the compounds. Under this condition, the TP yield was increased by 82% when compared to maceration. In addition, it was demonstrated that MAE used as a pretreatment to UAE was more efficient.

Industrial relevance

Olive leaves are usually considered as a residue with huge potential for value addition. High added-value compounds can be obtained by recovering phytochemicals from olive leaves for valorization through food products. The extraction of the bioactive compounds requires efficient techniques, but only a few studies show good extraction yields using clean techniques. Microwave-assisted extraction is a method for the extraction of bioactive compounds, which utilizes microwave energy to produce voluminous heating and the reduction of extraction time is one of the most attractive advantages of the system. In addition, the potential benefit of using microwave-assisted extraction as a pretreatment to ultrasound-assisted extraction to improve the recovery of bioactive compounds was reported and can be used as a means of intensifying the extraction process.

中文翻译：

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微波，超声波和常规技术从橄榄叶中提取生物活性化合物的比较（Olea europaea L.）

这项研究的目的是评估不同提取参数对橄榄叶中总酚（TP）化合物和抗氧化活性（AA）的影响（油橄榄）L.）使用微波辅助提取（MAE），超声辅助提取（UAE）和浸渍。该研究还强调了MAE和阿联酋条件的优化，以及使用MAE预处理阿联酋的潜在好处。结果表明，橄榄叶是具有高抗氧化活性的酚类化合物的良好来源。在较高的温度（86°C）下，MAE的TP收率更高，萃取时间较短（3分钟）。以水为溶剂进行的MAE有效地破坏了橄榄叶细胞，从而促进了化合物的释放。在这种条件下，与浸渍相比，TP的产量提高了82％。此外，已证明MAE用作阿联酋的预处理更为有效。

行业相关性

橄榄叶通常被认为是具有巨大增值潜力的残留物。高附加值的化合物可以通过从橄榄叶中回收植物化学物质以通过食品进行增值来获得。生物活性化合物的提取需要有效的技术，但只有少数研究表明使用清洁技术可获得良好的提取产率。微波辅助提取是一种提取生物活性化合物的方法，该方法利用微波能量产生大量热量，减少提取时间是该系统最吸引人的优势之一。另外，已经报道了使用微波辅助提取作为超声辅助提取的预处理以改善生物活性化合物的回收的潜在益处，并且可以用作增强提取过程的手段。