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Keywords:

  • Thymus vulgaris L.;
  • Lamiaceae;
  • Thyme;
  • Essential oil;
  • Seasonal variation;
  • p-Cymene;
  • Thymol;
  • GC-MS

Abstract

The seasonal variation in essential oil yield and composition from naturalized Thymus vulgaris L. in Central Otago, New Zealand, is reported. Essential oil yield (l/ha), from replicated, pilot-scale distillations, was influenced by both the field production of herb and the essential oil content of the herb. The oil yield peaked at 22.8 l/ha in December, after flowering had finished. Essential oil composition also varied significantly during the 13-month sampling period. Levels of the phenolic components, thymol and carvacrol, peaked at a total of 37% after flowering in summer (December and January). p-Cymene was an important component of Central Otago thyme oils and ranged from 40% to 50% in winter and early spring (May to October), declining to 21% in January. To maximize yields and phenol content of the oil, naturalized thyme in Central Otago should be harvested after flowering has finished in December.