Rutaceae (Citrus family)
The exterior of the fruit varies widely, from smooth to rugose, from green to orange to yellow. to marinate meat. In India, the unripe, pickled fruits are eaten as a side dish with curd rice (thayir sadam).
Bitter orange is famous as a main ingredient in orange marmalade. An oil (bitter orange oil) extracted from the dried peel is used to flavor sweets, ice cream, soft drinks, chewing gum, and liqueurs such as, for example, Cointreau and Curasao. An essential oil extracted from the fragrant flowers, called Neroli oil, is also employed in the production of sweets, drinks, and baked goods.
Comments. The peel of the bergamot orange (C. x bergamia) produces bergamot oil, an important ingredient in many perfumes and a flavoring in teas such as Earl Grey. Sour oranges are very hardy plants, relatively free of disease, and therefore cultivated as a rootstock for many other Citrus species. Extracts from the peel, which are thought to suppress the appetite, have been used in weight-loss products as a substitute for ephedra. Although used in ancient Chinese medicine, their effectiveness as an aid for weight loss is controversial.
Description. Evergreen shrub or small tree, 4-8 m (13-26 ft) tall and with many sharp spines. Alternate, obovate, strongly aromatic leaves with very broadly winged and leaflike, elliptic petioles, giving it a distinctive double-leaf look. Flowers white, hermaphroditic, with 5 petals. Almost spherical fruits 3-5 cm (1.2-2 in) in diameter, green turning yellow when ripe, with a thick, warty, rough rind. Segmented, juicy pulp with several whitish seeds and very acidic taste.
Origin and Distribution. Native to Southeast Asia, where the plant is widely grown in plantations and as a dooryard tree. This species requires a humid tropical or warm subtropical climate. Cultivated worldwide in the tropics and subtropics as a fruit tree or as a potted plant.
Food uses. The very sour juice of green fruits is used in Southeast Asia to add zest to drinks, desserts, ice cream, and also seafood dishes. In Southeast Asia the very fragrant, lime-scented leaves are widely used as a culinary spice to lend a characteristic flavor to savory and often spicy dishes like the famous tom yam soup of Thailand. The leaves are commonly combined with garlic, galangal, ginger, and chili to spice up stir-fries and Thai curries. Leaves and juice are employed together with several other spices to produce the typical Laotian and Cambodian vegetable paste called krueng, similar to Thai curry paste. In Indonesia, the leaves form an essential part of a dish called sayur asam, a popular meat and vegetable dish served with tamarind sauce. The oil of the fruit rind is used to flavor liqueurs and rum.
Comments. Leaves and fruit rind are used in parts of Southeast Asia in traditional herbal medicine. The oil of the rind has insecticidal properties.