Flavor constituents in fennel

Fennel has anise-like, slightly licorice, camphoraceous aroma. The flavor is warm, anisic with a bittersweet aftertaste.

The dried fennel fruit contains about 3-6% of volatile oil. The principal flavor constituents are anethole (50-60%), fenchone (20%), and various terpenes.

There are several varieties of fennel; both common and sweet fennel are grown for their fruits’ essential oil. Sweet fennel is also grown for the thickened bulb-like base of the leaf stems (often called anise), a 3- or 4- inch-wide structure that grows just above the ground.

Sweet fennel oil contains fenchone 1 -25% and anethole 30 -75%. While bitter fennel oil contains fenchone 12 - 25% and anethole 55 - 75%. Fenchones can be regarded as a character –impact of bitter fennel oil.

Fennel oils may contain up to 30% monoterpene hydrocarbons, among which limonene is dominant.
Flavor constituents in fennel

Fennel oil

Fennel oils are obtained from two cultivars of Foeniculum vulgare Miller: sweet fennel or bitter fennel. The oil contains up to 90% trans-anethole and up to 20% fenchone and small amounts of limonene, α -pinene, camphor and additional volatile compounds.

Sweet fennel oil is colorless or pale yellow to greenish with a characteristic smell of anise, fresh and spicy. Bitter fennel oil is colorless to pale yellow with a sharp, warm-camphoraceous, herbaceous odor, initially earthy, later sweet, anisic and spicy.

The main use for fennel oil is as a food flavoring, in liquors where a liquorice or anise taste is important, and in industrial perfumery to mask the odour of aerosols, insecticides, disinfectants, etc.
Fennel oil