Seasonal variation in essential oil content and chemical profile of mint in southeast of Brazil

ABSTRACT: This study evaluated the influence of seasonality in essential oil (EO) chemical composition of Mentha x piperita L. and Mentha viridis L. grown in southeast of Brazil. Leaves were collected from November 2011 until August 2013, in the middle of the following seasons: Spring (November), Summer (February), Autumn (May) and Winter (August). EO extraction was carried out by hydrodistillation in Clevenger apparatus for 1 hour. Chemical composition of EO was analyzed by GC-FID and GC-MS. The EO content and its chemical composition were influenced by seasonality in both species. The highest EO content was obtained for M. x piperita during spring (4.26%) and for M. viridis during spring (3.30%) and summer (3.70%). Mentha x piperita increased menthol (16.31 to 41.26%), neomenthol (3.02 to 6.39%) and menthone (5.56 to 41.58%) contents during spring and summer, respectively. Whereas, M. viridis EO content did not show a quality response pattern in relation to seasonality. Therefore, harvest time for M. x piperita is recommended during spring, and for M. viridis is recommended during spring and summer.

摘要：本研究评估了巴西东南部种植的辣薄荷（Mentha × piperita L.）与绿薄荷（Mentha viridis L.）的精油（essential oil, EO）化学组成受季节周期性的影响。研究于2011年11月至2013年8月期间采集样本叶片，采集时点分别对应下述季节的中期：春季（11月）、夏季（2月）、秋季（5月）与冬季（8月）。精油采用克莱文杰蒸馏器（Clevenger apparatus）通过水蒸馏法提取，提取时长为1小时。精油的化学组成通过气相色谱-氢火焰离子化检测器（GC-FID）与气相色谱-质谱联用仪（GC-MS）进行分析。结果表明，两种薄荷的精油含量及其化学组成均受季节周期性的显著影响。辣薄荷的精油含量峰值出现在春季（4.26%），绿薄荷的精油含量峰值则分别出现在春季（3.30%）与夏季（3.70%）。辣薄荷的薄荷醇（menthol）、新薄荷醇（neomenthol）与薄荷酮（menthone）含量分别在春季与夏季达到峰值，依次从16.31%提升至41.26%、从3.02%提升至6.39%、从5.56%提升至41.58%。与之相对，绿薄荷的精油化学组成并未呈现出与季节周期性相关的品质响应规律。因此，建议辣薄荷的采收时节为春季，绿薄荷的采收时节则为春季与夏季。