In this study, different drying methodologies (convective air, oven and microwave) of Myrtus communis L. (M. communis L.) leaves were conducted to investigate their effects on the levels of phenolic compounds, antioxidant capacity of ethanolic extracts (EEs) as well as the soybean oil oxidative stability. Drying methodology significantly influenced the extractability of phenolic compounds. Microwave drying led to an increase in the amounts of total phenols, flavonoids and proanthocyanidins followed by oven drying at 70 °C. Higher temperature of drying (100 and 120 °C) led to a significant reduction of their amounts (p < 0.05). An ultra-performance liquid chromatography method combined with high resolution mass spectroscopic detection was used to analyze the phenolic fraction of extracts. Higher amounts of the identified compounds were observed when leaves were heat treated. Furthermore, the evaluation of the antioxidant activity showed that the studied extracts possess in general high antioxidant capacities, significantly dependent on the employed drying methodology. The incorporation of the different extracts at 200 ppm in soybean oil showed that its oxidative stability was significantly improved. Extracts from leaves treated with microwave (EE_MW) and at 70 °C (EE_70) have better effect than BHT. The results of the present study suggest that microwave drying could be useful to enhance the extractability of phenolic compounds and the antioxidant capacity of M. communis L. leaf extract.

中文翻译：

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干燥方法对桃金娘叶片乙醇提取物中酚含量，抗氧化活性和大豆油氧化稳定性的影响

在这项研究中，对桃金娘（M. communis L.）叶片进行了不同的干燥方法（对流空气，烤箱和微波炉），以研究其对酚类化合物含量，乙醇提取物（EEs）的抗氧化能力的影响。以及豆油的氧化稳定性。干燥方法极大地影响了酚类化合物的可萃取性。微波干燥导致总酚，类黄酮和原花色素的含量增加，然后在70°C下进行烤箱干燥。较高的干燥温度（100和120°C）导致其用量明显减少（p <0.05）。超高效液相色谱法结合高分辨率质谱检测法用于分析提取物中的酚类成分。对叶片进行热处理后，观察到更高含量的鉴定出的化合物。此外，抗氧化活性的评估表明，所研究的提取物通常具有高抗氧化能力，这很大程度上取决于所采用的干燥方法。大豆油中200 ppm的不同提取物的掺入表明其氧化稳定性得到了显着改善。微波（EE_MW）和70°C（EE_70）处理的叶子的提取物比BHT有更好的效果。本研究的结果表明微波干燥可用于增强酚类化合物的提取能力和沙枣叶片提取物的抗氧化能力。抗氧化活性的评估表明，所研究的提取物通常具有高抗氧化能力，这在很大程度上取决于所采用的干燥方法。大豆油中200 ppm的不同提取物的掺入表明其氧化稳定性得到了显着改善。微波（EE_MW）和70°C（EE_70）处理的叶子的提取物比BHT有更好的效果。本研究的结果表明微波干燥可用于增强酚类化合物的提取能力和沙枣叶片提取物的抗氧化能力。抗氧化活性的评估表明，所研究的提取物通常具有高抗氧化能力，这在很大程度上取决于所采用的干燥方法。大豆油中200 ppm的不同提取物的掺入表明其氧化稳定性得到了显着改善。微波（EE_MW）和70°C（EE_70）处理的叶子的提取物比BHT有更好的效果。本研究的结果表明微波干燥可用于增强酚类化合物的提取能力和沙枣叶片提取物的抗氧化能力。微波（EE_MW）和70°C（EE_70）处理的叶子的提取物比BHT有更好的效果。本研究的结果表明微波干燥可用于增强酚类化合物的提取能力和沙枣叶片提取物的抗氧化能力。微波（EE_MW）和70°C（EE_70）处理的叶子的提取物比BHT有更好的效果。本研究的结果表明微波干燥可用于增强酚类化合物的提取能力和沙枣叶片提取物的抗氧化能力。