The chemical composition of essential oils isolated from sweet fennel fruits available as herbal tea products.

Unlabelled: Sweet fennel fruits (Foeniculum vulgare subsp. vulgare var. dulce Mill.) are a spice with various uses in medicine, but also in food, pharmaceutic and cosmetic industries. Their biological activities as well as the flavoring properties are due to the essential oil.
Aim: In this paper, the essential oils obtained from seven Romanian fennel herbal tea products were comparatively characterized in terms of their chemical composition.
Material and Methods: The volatile oils obtained by hydrodistillation, according to the Ph. Eur. 6th edition, were analyzed by GC and GC-MS.
Results: The volatile oil content of fennel herbal tea products varies widely (28.10-101.00 mL/kg dried fruits), but all the samples meet the requirements of the Ph Eur. 6th edition (min. 20 mL/kg dried fruits). Phenylpropanoid derivatives (52.12%-57.66%) and monoterpenes (39.25%-45.28%) represent the bulk of the fennel volatile oils. Trans-anethole, estragole, limonene, fenchone, a-pinene, y-terpinene and myrcene were the main compounds in all samples, but their levels vary greatly.
Conclusions: The Romanian fennel herbal tea products showed important differences in terms of volatile oil content. The qualitative and quantitative differences in the chemical composition of fennel volatile oils were also observed. The most striking variations concern trans-anethole and estragole phenylpropanoid derivatives. Furthermore, these variations could have a significant impact on the flavouring and biological effects of fennel volatile oils.