Common/vernacular names: Expressed
grapefruit oil, cold-pressed grapefruit oil, and
shaddock oil.
GENERAL DESCRIPTION
A cultivated tree with large fruits, often over
10 m high; is considered to be a relatively
recent hybrid ofC. maximaandC. sinensis.
Numerous cultivars are grown commercially;
‘‘Duncan’’ is the standard type grown in Flor-
ida (TUCKER AND LAWRENCE); cultivated in the
United States (especially California, Florida,
and Texas), the West Indies (e.g., Jamaica and
the Dominican Republic), Nigeria, Brazil, and
Europe (e.g., Israel and Portugal). Part used is
the fresh peel of the fruit from which grape-
fruit oil is produced by cold expression. Nar-
ingin extract is a bitter flavoring material
prepared by extraction of the expressed peel;
it is not pure naringin.
CHEMICAL COMPOSITION
Grapefruit oil contains mostly the monoter-
pene hydrocarbon, limonene (ca. 90%). Other
volatileconstituentsincludesesquiterpenes(e.
g., cadinene and paradisiol or intermedeol);1,2
aldehydes (C 7 to C 12 aldehydes, neral, gera-
nial, perillaldehyde, citronellal, a-sinensal,
andb-sinensal); esters (e.g., geranyl acetate,
neryl acetate, perillyl acetate, octyl acetate,
decyl acetate, citronellyl acetate,trans-carvyl
acetate, 1,8-p-menthadien-2-yl acetate, and
1,8-p-menthadien-9-yl acetate); and nootka-
tone (a bicylcic sesquiterpene ketone); among
others (GUENTHER;LIST AND HO€RHAMMER).1–6
The oil also contains sizable amounts (ca.
1.4%) of coumarins and furocoumarins (bergap-
tens) composed mainly of 7-geranoxycoumarin,
with marmin, osthol, limettin, 7-methoxy-8-
(2-formyl-2-methylpropyl) coumarin, ber-
gapten, bergamottin, dihydroxybergamottin,
bergaptol, byakangelicin, 5-[(3,6-dimethyl-6-
formyl-2-heptenyl)-oxy] psoralen, and a
chromen-7-one also present.7–10
The characteristic grapefruit aroma and
flavor of grapefruit oil is reported to be due
primarily to nootkatone and other carbonyls
present (e.g., geranyl acetate, neryl acetate,
octyl acetate, 1,8-p-menthadien-2-yl acetate,
and others).1,11–13
Thecharacteristicbittertasteofgrapefruitis
due to naringin present mainly in the peel.14,15PHARMACOLOGY AND BIOLOGICAL
PROPERTIESGrapefruit oil is reported to have antibacterial
activities.^16 Its chromenone constituent has
been shown to enhance antibiotic effect against
MSSA and MRSA by acting as an inhibitor of
the bacterial efflux pump mechanism.^7
The olfactory stimulation resulting from
the scent of grapefruit oil has a sympathomi-
metic stimulating effect that results in an
increase in blood pressure, increased lipolysis,
and reduced body weight gain in experimental
animals and in humans.17–20TOXICOLOGYGrapefruit oil has been reported to promote
tumor formation on mouse skin by the
primary carcinogen, 9,10-dimethyl-l,2-
benzanthracene.^21
Certain bergaptens are known to be photo-
toxic and allergenic to humans (seebergamot
oil).
Dermatological studies have indicated
grapefruit oil to be nonirritating, nonsensitiz-
ing, and nonphototoxic to humans.^16USESMedicinal, Pharmaceutical, and Cosmetic.
Grapefruit oil is used as a fragrance compo-
nent in soaps, detergents, creams, lotions, and
perfumes, with maximum use level of 1.0%
reported in perfumes.^16Food. Grapefruit oil is extensively used as a
flavor ingredient in alcoholic and nonalcohol-
ic beverages (especially soft drinks), frozen
dairy desserts, candy, baked goods, gelatins
and puddings, and milk products, with highest
maximum average use level of about 0.108%
(1084 ppm) reported in candy.344 Grapefruit oil