Effect of drying on the yield and chemical composition of essential oils obtained from Mentha Longifolia leaves

The present study was carried out to evaluate the influence of the drying mode (under the sun) on the yield and composition of essential oils extracted from leaves (fresh and sun dried) of Mentha longifolia. Drying under the sun increased the concentration of essential oils isolated by hydrodistillation in a Clevenger apparatus. Twenty-three components were identified by using gas chromatography (GC) and GC coupled to mass spectrometry (GC–MS). The chemical composition was dominated by the presence of piperitenone oxide, in both essential oils obtained from fresh and sun dried mentha leaves. These results showed that the drying has a significant variation on essential oils yield and affected the qualitative and quantitative constituents of their composition.