EFFECT OF FREEZE DRYING ON THE CHEMICAL COMPOSITION OF LEMON BALM LEAVES (Melissa officinalis, L.)

This research focuses on the analysis of the chemical component of essential oil of lemon balm. The essential oil of leaves was obtained by extraction. The chemical components of the essential oil of lemon balm were analyzed by capillary GC and GC/MS and 8 substances were identified. The quality of the final product depends heavily on the operation of freeze drying (FD). It was found that essential oil content was more influenced by chamber pressure (high and low). Higher chamber pressure tended to lengthen the drying time but major volatile compounds of lemon balm. Comparative determinations of the essential oil in fresh and dried material at high pressure showed slightly higher content of the oil in the fresh one. The effect of freeze drying method on peltate glandular hairs structure was observed by electro-microscopy.