The Effect of Drying Process on the Physiochemical Characteristics and Quality of Basil Leaf Leaves

Basil contains high phenolic compounds and its seeds contain mucilages. By investigation the essential oils of this plant, and especially its phenylpropanoid compounds, have been identified as the main medicinal product.

In this research, basil leaves were dried by three

shadow, drying oven method at 40 and 60° C and microwave method at 180 and 360 W. In order to increase the heat transfer in short time some effective factors concerned with the leaves, namely moisture, iron, potassium,vitamin C and polyphenol contents were determined.

The first stage of drying rate is constant and controlled by external factors, was seen only in the shadow drying method. In two other methods, this stage has been almost eliminated.  Forced convection heat transfer coefficients is higher than natural convection coefficient. Therefore in the oven drying method, mass transfer rate is higher than the other methods. With increasing microwave power, drying time decreased. The determined amounts of iron, potassium and vitamin C showed that there is a significant difference between different drying methods (P <0.05).The longest drying time was in shadow with1800 minutes and the highest amount of vitamin C, iron and phenolic compounds was in the dried treatment in the shade.

According to the results, it can be stated that the drying of the basil leaf using shade drying and microwave drying at 180 W, are desirable because the amount of active ingredients in the plant is considerably retained.