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