Müberra Ko¸sar,* Temel Özek, Mine Kürkçüoglu and K. Hüsnü Can Ba¸ser
Abstract: Microwave-assisted hydrodistillation (MWHD) and hydrodistillation (HD) were carried out for the analysis of
volatile components in whole and ground fruits of ,i>Foeniculum vulgare Miller (fennel). Fruits were distilled using a
microwave oven modified to fit a Clevenger-type apparatus. The effect of microwave energy on the yield and composition
of the essential oil was investigated against the classical hydrodistillation. All the essential oils were analyzed by
GC-FID and GC/MS. (E)-anethole was found as the main compound in the oils of both whole and ground materials
(82.2–86.8%) using the two methods. Methyl chavicol (4.0–4.9%) and limonene (2.2–4.9%) were also found in fennel
oils obtained by HD and MWHD. The amounts of identified components in the oils obtained from whole and ground
fennel fruits were not affected significantly by microwave energy except for limonene.
The fruits of Foeniculum vulgare Miller (Fennel) (Apiaceae) are used as a spice in Europe, Northern Africa, West, Central and South Asia, as well as Turkey. Fennel fruits are used as appetizers, digestive, sedative and colic (1) and added in breads, fishes, salads and cheeses as a spice (2). Two varieties of fennel are known and reported in the European Pharmacopoeia. Foeniculum vulgare Miller subsp. vulgare var. vulgare known as bitter fennel contains (E)-anethole (60%) and fenchone (15%) and F. vulgare Miller subsp. vulgare var. dulce (Miller) Thellung known as sweet fennel contains (E)-anethole (80%) as the main component. The oil of fennel fruits is used as an ingredient of cosmetic and pharmaceutical products for its balsamic, cardiotonic, digestive, lactagogue and tonic properties. The composition of the oil of fennel has been reported. (E)-Anethole, fenchone (present in bitter varieties), estragole (methyl chavicol), limonene, α−pinene, and α−phellandrene were found as the main components (2–5). The amount of methyl chavicol and the ratio of (E)-anethole and methyl chavicol vary between the two types. The carcinogenic effect of methyl chavicol has been reported. Scientific committee on food of European Commission reported its opinions on methyl chavicol in 2001 (6). In this report, chemical characterization, exposure assessment, metabolism, and toxicity of methyl chavicol were given. According to this report, limited with respect to the standard long-term bio-assays, have shown that methyl chavicol is a weak inducer of hepatocarcinogenicity in mice treated orally, by i.p. or s.c. injection. The induction of liver tumours seems to depend on formation of 1’-hydroxymetabolites. Metabolic studies indicate that in the high dose range of carcinogenicity studies (150–600 mg/kg bw) the production of 1’-hydroxy-methyl chavicol, expressed as percentage of the dose, is about 5–10 times higher than that at lower doses (0.05–50 mg/kg bw). 1’-Hydroxyestragole has been found also in the urine of men dosed with 100 μg estragole/day for six months. Methyl chavicol occurs naturally in a variety of foods including tarragon (60–75%), sweet basil (20–43%), sweet fennel (5–20%), green anise (1%), and star anise (5–6%). There are 28 food categories identified by industry to which methyl chavicol can be added. For these food categories, a concentration of 10 mg methyl chavicol/kg food was assumed for food in general and a concentration of 50 mg/kg for food containing herbs and spices.
