Yuzu (Citrus junos, from Japanese ユズ or 柚子) is a citrus fruit and plant in the family Rutaceae. It is called yuja (from Korean 유자) in Korean cuisine. Both Japanese yuzu and Korean yuja are cognates of the Chinese yòuzi (柚子), but the Mandarin word refers to the pomelo. Yuzu is called xiāngchéng (香橙) in Mandarin.
The fruit looks somewhat like a small grapefruit with an uneven skin, and can be either yellow or green depending on the degree of ripeness. Yuzu fruits, which are very aromatic, typically range between 5.5 cm (2.16 in) and 7.5 cm (2.95 in) in diameter, but can be as large as a regular grapefruit (up to 10 cm (3.93 in) or larger).
Yuzu forms an upright shrub or small tree, which commonly has many large thorns. Leaves are notable for a large, leaf-like petiole, resembling those of the related kaffir lime and ichang papeda, and are heavily scented.
Yuzu closely resembles sudachi (a Japanese citrus from Tokushima Prefecture, a yuzu-mandarin orange cross) in many regards, though unlike the sudachi, yuzu eventually ripen to an orange colour and there are subtle differences between the flavours of the fruit.
The yuzu originated and grows wild in central China and Tibet. It was introduced to Japan and Korea during the Tang Dynasty, and is still cultivated there. It grows slowly, generally requiring 10 years to fruit. To shorten duration to fruiting, it may be grafted with karatachi (P. trifoliata). It is unusual among citrus plants in being relatively frost-hardy, due to its cold-hardy C. ichangensis ancestry, and can be grown in regions with winters as low as -9 °C (15 °F) where more sensitive citrus would not thrive.
Varieties and similar fruits
In Japan, an ornamental version of yuzu called hana yuzu (花ゆず, 花柚子) “flower yuzu” is also grown for its flowers rather than its fruit. A sweet variety of yuzu known as the yuko, only present in Japan, became severely endangered during the 1970s and 1980s; a major attempt has been made to revive this varietal in southern Japan. Another variety of yuzu in Japan, with knobby skin is called shishi yuzu (獅子柚子, literally “lion yuzu”).
Though rarely eaten as a fruit, yuzu is a common ingredient in Japanese cuisine, where the aromatic zest (outer rind) as well as juice are used much in the same way that lemons are used in other cuisines. The yuzu’s flavor is tart and fragrant, closely resembling that of the grapefruit, with overtones of mandarin orange.
It is an integral ingredient (along with sudachi, daidai, and other similar citrus fruits) in the citrus-based sauce ponzu, and yuzu vinegar is also produced. Yuzu is often combined with honey to make yuzu hachimitsu (柚子蜂蜜)—a kind of syrup that is used to make yuzu tea (柚子茶), or as an ingredient in alcoholic drinks such as the yuzu sour (柚子サワー). Yuzu kosho (also yuzukosho, literally “yuzu and pepper”), is a spicy Japanese sauce made from green or yellow yuzu zest, green or red chili peppers, and salt.
It is used to make liquor (such as yuzukomachi, 柚子小町) and wine.
Slivered yuzu rind is used to garnish a savoury, salty egg-pudding dish called chawanmushi, as well as miso soup. It is often used along with sudachi and kabosu.
In Korean cuisine, yuja is most commonly used to make yuja-cheong (yuja marmalade) and yuja tea. Yuja-cheong can be made by sugaring peeled, depulped, and thinly sliced yuja, and yuja-cha (yuja tea) can be made by mixing hot water with yuja-cheong. Yuja-hwachae (yuja punch), a variety of hwachae (fruit punch), is another common dessert made with yuja. Yuja is also a common ingredient in Korean-style western food, such as salads.
Yuzu is also known for its characteristically strong aroma, and the oil from its skin is marketed as a fragrance. In Japan, bathing with yuzu on Tōji, the winter solstice, is a custom that dates to at least the early 18th century. Whole yuzu fruits are floated in the hot water of the bath, sometimes enclosed in a cloth bag, releasing their aroma. The fruit may also be cut in half, allowing the citrus juice to mingle with the bathwater. The yuzu bath, known commonly as yuzuyu (柚子湯), but also as yuzuburo (柚子風呂), is said to guard against colds, treat the roughness of skin, warm the body, and relax the mind.
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Yuzu is also even used in the flavoring of many snack products, such as chips and chocolate bars.
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Yuzuyu dates from the Edo period (1603–1868) and may have been partially inspired by a form of Japanese wordplay called goroawase—the characters for “winter solstice” (冬至) and “hot-spring cure” (湯治) can both be read as tōji.
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