The effect of drying conditions on the color of tarragon (Artemisia dracunculus L.) leaves was studied. Tarragon leaves were dried at temperatures of 40 to 90°C with a constant airflow of 0.6 m/s. The samples were collected at 7%, 10%, 20%, and 30% moisture content wet basis for evaluation of the color change. The color parameters of fresh and dried leaves were measured by a colorimeter. The individual parameters of L*a*b* and L*C*h°color systems were evaluated and h°proved to be the best parameter to monitor color change. The smallest change of the color parameters was observed at 40°C, in which temperature was low, and also at 90°C, when drying time was short. The biggest change occurred at the temperatures of 50 to 70°C. Most of the color change happened before the material reaches 35% moisture content. The combination of drying time and temperature defines the change of color.

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 tarragon.