Onion

Onion (Allium cepa) is a perennial or biennial herb up to 1.2 meters high with hollow leaves and flowering stem, and a globe like fleshy bulb. It belongs to Liliaceae family.

Onion is native of western Asia and the Middle East; it has a long history of cultivation all over the world, mainly for culinary uses.

The essential oil is mainly produced in France, Germany and Egypt from the 'red' onion. It is obtained by steam distillation of the bulb. It is a pale-yellow or brownish-yellow mobile liquid with strong, unpleasant, sulphuraceous odour with a lachrymatory effect. The principal constituents of these essential oils are dipropyl disulphide, also methylpropyl disulphide, dipropyl trisulphide, and methylpropyl trisulphide and allylpropyl disulphide, among others.

The onion essential oil is used in some pharmaceutical preparations and it is extensively used in most major food categories, especially meats, savouries, salad dressings, as well as alcoholic and soft drinks. It is not used in perfumery work.