Effect of Drying on Essential Oil Yields and Chemical Composition of Pineapple Mint (Mentha rotundifolia ‘variegata’) from China

Abstract

The fresh leaves of pineapple mint (Mentha rotundifolia ‘variegata’) were dried by air-drying at ambient temperature (22°C) and oven-drying at 60°C. The essential oils of each treatment were isolated by hydrodistillation (HD) and analysed by GC-MS and retention index comparison. The results showed that the yields of the oils were significantly affected by the drying methods. Higher oil yields by air-drying at 22°C was obtained when compared with oven-drying (0.63 % and 0.31 %, respectively), while the effect of drying methods on the chemical components of the essential oils were not significantly different. Thirty-three and thirty-one components, (99.06 % and 98.75 % of the total oils, respectively), were identified from the two oils. The main components were cis-jasmone (36.77 % by air-drying, 32.43 % by oven-drying), germacrene D (11.89 %, 10.88 %), β-ocimene (10.51 %, 11.27 %), viridiflorol (8.20 %, 8.47 %), octenyl acetate (6.41 %, 6.74 %), and β-farnesene (4.22 %, 5.66 %).