The Effect of Growing Conditions and Different Drying Methods on Drying Time, Essential Oil Content, Color Characteristics and Microbial Load of Dracocephalum Moldavica L.

Drying, is one of the important postharvest processes of medicinal plants with an important role played in quality and quantity of the drugs. In this research, in order to study the effect of growing conditions and different drying methods on drying time, essential oil content, color characteristics and microbial load of Dracocephalum moldavica, a Factorial experiment in Randomized Complete Block Design (RCBD) of two factors namely: drying method (five methods) and growing conditions (two conditions), of three replications was performed. The five treatments followed in the drying method were comprised of: 1- sun drying, 2- drying in shade at room temperature, 3- Oven drying at 30°C, 4- Oven drying at 40°C, and 5- Oven drying at 50°C, while the treatments for the growing conditions were:1- cultivation in greenhouse and 2- cultivation in field. The drying process was continued until the moisture content of either about 10% on a wet basis or on a dry basis was obtained. The results indicated the significant effect of treatments on all the evaluated factors. Also for both conditions (field and greenhouse), the minimum drying time (11 and 14 hours) belonged to 50°C for oven treatment while maximum drying time (55 and 73 hours) belonged to drying in shade. The maximum essential oil content (in both conditions)was related to shade drying, while the minimum content achieved at 50°C treatments. Also, it was observed that 50°C and sun drying treatments significantly decreased the plants microbial load.