The effect of air-drying on glycosidically bound volatiles from seasonally collected origano (Origanum vulgare ssp. hirtum) from Croatia

The glycosidically bound volatiles were isolated from fresh and airdried origano by exhaustive percolation with ethyl acetate. After the purification of glycosidic fraction, the enzymatic hydrolysis with beta-glucosidase was performed. The obtained aglycones were analysed by GC-MS. Eighteen compounds were identified. The seasonal variations of main aglycone contents from the fresh plant material were: thymoquinone (3.10-6.18 mg/kg), benzyl alcohol (1.33-3.62 mg/kg), 3,5,5-trimethyl-4-(3-hydroxy-1-buthenyl)-2-cyclohexen-1-on (0.51-3.35 mg/kg), 2-phenyl ethanol (0.42-2.98 mg/kg), eugenol (0.93-2.55 mg/kg), thymol (0.70-1.40 mg/kg) and carvacrol (0.88-1.40 mg/kg). The season of collecting influenced the content and composition of the glycosidically bound volatiles of origano. Air-drying effected mostly the yield of these compounds.