Loss of essential oil of tarragon (Artemisia dranunculus L.) due to drying

The effect of hot air-drying on the essential oil constituents and yield in French and Russian tarragon (Artemisia dracunculus L.) leaves was studied. The tarragon leaves were dried at air temperatures ranging from 40 to 90 °C. The drying stopped when the moisture content of the samples reached 10% or for some of the treatments reached 7, 20 and 30%. The essential oil of the fresh and dried leaves was isolated by hydrodistillation and analysed by capillary gas chromatography and gas chromatography-mass spectrometry. The decrease of oil during the drying process was highest at 60 °C drying temperature. For French tarragon the decrease in the amount of oil was significantly lower at 90 °C. The effect of the relative humidity of the drying air at each temperature was not significant. The main compounds were estragole in French tarragon (69%) and sabinene in Russian tarragon (40%). The drying process changed the relative percentage of the constituents in the oil; for instance, the relative percentages of estragole decreased and sabinene increased in French tarrago