Application
Onion oil is an obvious high-quality functional product; however, its application in the food industry is relatively limited. Currently, it is mainly used in the flavor and fragrance industry, and there are still many shortcomings in its application in functional foods. Among these, extraction methods and flavor processing are the main influencing factors.
Description
Herbaceous plant originally from the Middle East, but today widespread
throughout the world because of the large consumption of
the edible bulb, the only part used. The stalk can reach approximately
1 m (39 in.) in height. The bulb consists of several concentric
tunics. Onion has a strong, pungent, lasting odor and a
characteristic onion flavor.
The essential oil is obtained by distillation of the bulbs with yields
of about 0.02%. The physical-chemical constants vary widely,
depending on the origin of the plant. The oil is a yellowish liquid
with a characteristic onion odor. Main constituents of the oil are
d-n-propyl disulfide and methyl-n-propyl disulfide.
The derivatives are oleoresin, fluid concentrated water extract, and
the fluid extract. The first two derivatives are obtained by special
manufacturing processes from thermally pretreated bulbs in order
to enhance some flavor top notes, as well as the flavoring strength.
Chemical Properties
Obtained by steam distillation of the bulbs with yields of about 0.02%. The physical–chemical constants vary widely,
depending on the origin of the plant. The oil has a characteristic onion odor.
Physical properties
The oil is a clear, amber-yellow-to-amber-orange liquid. It is soluble in most fixed oils, mineral
oil and alcohol. It is insoluble in propylene glycol and glycerin.
Definition
Extractives and their physically modified derivatives. Allium cepa, Liliaceae.
Essential oil composition
Main constituents of the oil are d-n-propyl disulfide and methyl-n-propyl dilsufide.
