The object of the present study was to investigate the effect of different drying methods on percentage and components of volatile oil distilled from some aromatic plants leaves. The natural sun drying at 30°C ±1 and the artificial drying using artificial batch dryer are the two different methods used to dry the leaves. Drying methods were carried out under three different levels of air temperature (35, 40 and 45 oC), and air velocity of (2 m/s), for different plants spearmint (Mentha viridis L.), sage (Salvia officinalis L.), and sweet basil (Ocimum basilicum,L. var. basilicum).
The obtained results indicated that:-
1- In natural drying, moisture content decreased from 88.7 to 13.7 %, 85.6 to 14.1 % and 89.2 to 13.9 % at drying time of 42, 46 and 44 hours for spearmint, sage and sweet basil, respectively.
2- In artificial drying the recorded drying times at drying air temperature of 35, 40 and 45 oC were 18, 16 and 14 hours for spearmint 20, 18 and 16 hours for sage, and 20, 18 and 16 hours for sweet basil moisture content decreased from 88.7 to 13.7 %, 85.6 to 14.1 % and 89.2 to 13.9 % for spearmint, sage and sweet basil, respectively.
3- Percentage of volatile oils distilled from the leaves of the studied aromatic plants, varied and it decreased as the drying air temperature increased over 40 oC.
4- The optimum distillation time to distillate volatile oils for dry leaves from spearmint, was one hour, while it was two hours for sage and sweet basil.
5- The maximum percentage of volatile oil components were obtained from artificial drying at 40 oC and sir velocity of 2 m/s.
6- Artificial drying of the studied plants at drying air temperature of 40 oC is recommended for shorter drying time, higher percentage of volatile oil, and getting dried plants without contamination.