f302 Mandarin

Citrus fruits constitute several species of the genus Citrus of the subfamily Aurantiodeae of the plant family Rutaceae.

The mandarin is a small, deep-orange-coloured orange. The skin is loose and easily peeled. The mandarin orange is considered a native of south-eastern Asia and the Philippines. It is most abundantly grown in Japan, southern China, India, and the East Indies. These fruits have never been as popular in Western countries as they are in the Orient. For commercial exploitation, mandarins have several disadvantages, including that (unlike the orange) the fruit does not ship well. But increasing cultivation in non-Eastern tropical areas has led to increasing availability.

Since the mandarin is easy to peel, it is a natural fruit for eating out of hand. The sections are also utilised in fruit salads, gelatins, puddings, and cakes. Very small types are canned in syrup. The dried rind is often used as a flavouring. The essential oil is expressed from the peel, and with terpenes and sesquiterpenes removed, is employed in flavouring hard candy, gelatins, ice cream, chewing gum, liqueurs and bakery goods. Mandarin essential-oil paste is a standard flavouring for carbonated beverages. Petitgrain mandarin oil, distilled from the leaves, twigs and unripe fruits, has the same food applications. Unlike orange, mandarin is not widely used as a juice.

The fruit is said to be antiemetic, aphrodisiac, astringent, laxative and tonic. The flowers, pericarp, endocarp, exocarp and seed are said to have a number of medicinal properties and to have been used in the treatment of a number of ailments.

Mandarin essential oil and petitgrain oil, and their various tinctures and essences, are valued in perfume manufacturing. The substance bergapten, from this and other citrus fruits, is sometimes added to tanning preparations, since it promotes pigmentation in the skin; though it can cause dermatitis or allergic responses in some people. Some of the plant’s more recent applications are as sources of anti-oxidants and chemical exfoliants in specialised cosmetics.

Allergen Description

The following allergen(s) have been characterised:

• Cit r 3, a lipid transfer protein. (1, 2)
• Cit r 3 is present in mandarin peel and also in the pulp. (1)

The presence of a profilin has been inferred through a study reporting that hypersensitivity to Bet v 2 was strongly associated with clinical allergy to citrus fruit (orange, mandarin, or both): 39% of subjects were monosensitised to Bet v 2, compared to 4% monosensitised to Bet v 1. (3)

A cross-reactive 30 kDa protein has also been detected. (4)

Potential Cross Reactivity

An extensive cross-reactivity among the different individual species of the Rutaceae or citrus family could be expected, (5) but has not been reported specifically for mandarin.

Mandarin contains a lipid transfer protein (LTP), Cit r 3, which is expected to result in cross-reactivity with other LTPs, in particular those in other citrus fruits. Two citrus-fruit LTP allergens, orange Cit s 3 and lemon Cit l 3, have previously been characterised, and sensitisation to these allergens has been detected in in a group of Spanish orange-allergic patients: in around 50 to 45% by in vitro testing, and in 27 to 37% by skin-prick testing. (6)

Cross-reactivity between mandarin and other profilin-containing foods and plants is possible. (2)

A peanut-allergic patient was described who exhibited co-sensitivity to citrus seed and had experienced anaphylaxis to lemon soap. The major protein component of citrus seed is a globulin seed storage protein, citrin, which was shown to be completely cross-reactive between seeds from various citrus fruits (orange, lemon and mandarin), and partially cross-reactive between peanut and orange seed extracts. (7)

A patient who had experienced allergic responses to various fruits developed an acute anaphylactic reaction after the ingestion of peach. The patient's serum contained IgE antibodies reactive to extracts from peach, guava, banana, mandarin, and strawberry, but not apple, pear, or nectarine. A common 30 kDa protein was demonstrated, which was not present in extracts from pear or apple. (3)

Clinical Experience

IgE-mediated reactions

Anecdotal evidence suggests that Mandarin may occasionally induce symptoms of food allergy in sensitised individuals; however, few studies have been reported to date. (1) Clinical presentation of citrus fruit allergy, reported mostly for orange, is heterogeneous, varying from mild oral allergy syndrome to severe anaphylaxis. (1, 8) Biphasic anaphylactic reactions have been reported following ingestion of mandarin. (9)

Importantly, individuals allergic to mandarin or another citrus fruit may not necessarily be allergic to all citrus fruits. For example, in a study of 6 patients with orange allergy (type-1 hypersensitivity after ingestion of orange juice and a positive skin-prick test on at least 2 occasions), 3 patients tolerated small quantities of lemon juice, and 1 patient tolerated mandarin; but 2 patients experienced oral allergy syndrome to this fruit. Serum orange-specific IgE was raised in all patients, mandarin-specific IgE in 5 patients (highest 6.04), lemon-specific IgE in 6 patients, and grapefruit-specific IgE in 5. (7) Cross-reactivity was not evaluated.

A 24-year-old-woman was described who experienced an anaphylactic reaction (pronounced oral allergy syndrome, throat swelling, angio-oedema of the face, and severe bronchospasm) beginning within half an hour after ingestion of a mandarin. Mandarin-serum specific IgE was 5.18 kUa/l, and 5.26 kUa/l for lemon, 3.07 kUa/l for orange, and 2.21 kUa/l for grapefruit. Specific IgE for house dust mite and bromelain (both indicators of sensitisation against cross-reactive carbohydrate determinants) was negative. She was shown to be sensitised to orange (Cit s 3) and mandarin (Cit r 3) LPT allergens, as well as to a germin-like allergen, Cit s 1. Her sensitisation was confirmed by skin-prick testing and basophil-activation testing (BAT). (1)

Allergic symptoms were observed in farmers engaged in mandarin farming, but might not have been due to Mandarin, but to pesticides, mites, or some other cause. (10)

Other reactions

Contact dermatitis from the essential oil of mandarin in fragrance has been reported. (11).Occupational asthma in a mandarin-orchard worker, from inhaling arrowhead scale dust, has been reported. (12).Obstruction of the small intestine due to orange and mandarin has been reported. (13, 14) Reactions have also been noted to mandarin seeds.

Last reviewed: June 2022.