The impact of both the season of collection and drying on the volatile constituents of Origanum vulgare L. ssp hirtum grown wild in Croatia

Samples of Origanum vulgare ssp. hirtum were collected from the same geogra phic area in the south of Croatia at different seasons of growth. The maxim um fluctuations found for the main components from fresh plant material wer e: thymol [149.2-1124.4 mg (100 g)(-1)], carvacrol [51.6-564.3 mg (100 g)(- 1)], p-cymene [20.2-220.9 mg (100 g)(-1)] and gamma -terpinene [50.1-217.5 mg (100 g)(-1)]. The oregano that was analysed belonged to a thymol/carvacr ol chemotype. The season of collecting affected the qualitative and quantit ative composition of the essential oil. The most impressive difference was the increase of p-cymene content in August. After the drying of the plant m aterial, all samples showed a minor decrease in essential oil yields when c ompared with fresh plants. Drying, at room temperature, had no effect on th e qualitative composition of oregano oil. Because of the variability of ess ential oil compositions from seasonally collected fresh and dried oregano, it would be important to check the quantity and quality of such components before usage.