Effect of different drying treatments on essential oil yield, composition and color characteristics of Kelussia odoratissima Mozaff

Abstract

Kelussia odoratissima is known as an endemic and valuable spice plant. The effect of six different drying treatments (sun, shade, oven 45°C, oven 65°C, microwave and freeze drying) was studied on the color, essential oil content and chemical composition of K. odoratissima leaves. The essential oils were isolated from fresh and dried samples by a hydrodistillation method and analyzed using gas chromatography–mass spectrometry (GC–MS). The highest essential oil yield was obtained by shade drying (1.50%) followed by microwave (1.46%) and oven 65°C (1.43%)-drying methods. The major compounds of K. odoratissima oils were (Z)-ligustilide, (E)-ligustilide and cis-3-butylidene phthalide. Drying treatments significantly increased (Z)-ligustilide compared with the fresh one. In this study, (Z)-ligustilide ranged from 48.67% in sun-dried samples to 68.3% in 45°C oven-dried ones. For color analysis, shade drying possessed the highest a*/b* value, followed by microwave and oven 45°C. Results showed that shade drying at ambient temperature significantly increased the essential oil yield and (Z)-ligustilide with acceptable color quality. Finally, shade and oven drying (<50°C) methods were introduced to produce appreciable essential oil yield, composition and color quality.