Lychee

Lychees ( LEE-chee) are the fruit of the tree Litchi chinensis, the sole member of the genus Litchi, part of the soapberry family, Sapindaceae. They are edible, with a sweet, mildly tart flavor, and have a distinctive floral aroma often described as rose-like. There are three distinct subspecies of lychee. The most common is the Indochinese lychee, found in South China, Malaysia, and northern Vietnam. The other two are the Philippine lychee (locally called alupag or matamata), found only in the Philippines, and the Javanese lychee, cultivated in Indonesia and Malaysia. The tree has been introduced throughout Southeast and South Asia. Cultivation in China has been documented since the 11th century. China is the main producer of lychees, followed by India, Vietnam, other countries in Southeast Asia, other countries in South Asia, Madagascar, and South Africa. A tall evergreen tree, it bears small fleshy sweet fruits. The outside of the fruit is a pink-red, rough-textured soft shell. Lychee seeds contain methylene cyclopropyl glycine, which has caused hypoglycemia associated with outbreaks of encephalopathy in undernourished Indian and Vietnamese children who consumed lychee fruit.

Taxonomy

Litchi chinensis is the sole member of the genus Litchi in the soapberry family, Sapindaceae. It was described and named by French naturalist Pierre Sonnerat in his account Voyage aux Indes Orientales et à la Chine, fait depuis 1774 jusqu'à 1781 (translation: Voyage to the East Indies and China, made from 1774 to 1781), which was published in 1782. There are three subspecies, determined by flower arrangement, twig thickness, fruit, and the number of stamens.

Litchi chinensis subsp. chinensis is the only commercialized lychee. It grows wild in southern China, northern Vietnam, and Cambodia. It has thin twigs; the flowers typically have six stamens; and the fruits are smooth or have protuberances up to 2 mm (0.079 in). Litchi chinensis subsp. philippinensis (Radlk.) Leenh is common in the wild in the Philippines and rarely cultivated. Locally called alupag, mata-mata, or matamata due to its eye-like appearance when the fruit is opened, it has thin twigs, six to seven stamens, and long, oval fruit with spiky protuberances up to 3 mm (0.12 in). Litchi chinensis subsp. javensis is only known to be cultivated in Malaysia and Indonesia. It has thick twigs, flowers with seven to eleven stamens in sessile clusters, and smooth fruit with protuberances up to 1 mm (0.039 in).

Description

Tree Litchi chinensis is an evergreen tree that is frequently less than 15 m (49 ft) tall, sometimes reaching 28 m (92 ft). Its leaves, 12.5 to 20 cm (4.9 to 7.9 in) long, are pinnate, having 4 to 8 alternate, elliptic-oblong to lanceolate, abruptly pointed leaflets, The bark is grey-black and the branches a brownish-red. The leaves are 12.5 to 20 cm (4.9 to 7.9 in) long, with leaflets in two to four pairs. Lychees are similar in foliage to those of the family Lauraceae, likely due to convergent evolution. They adapted by developing water-repellent leaves which are called laurophyll or lauroid leaves. Flowers grow on a terminal inflorescence with many panicles on the current season's growth. The panicles grow in clusters of 10 or more, reaching 10 to 40 cm (3.9 to 15.7 in) or longer, holding hundreds of small white, yellow, or green flowers that are distinctively fragrant.

Fruit

The lychee tree bears fleshy fruits that mature in 80 to 112 days depending on climate, location, and cultivar. Fruits vary in shape from round to ovoid to heart-shaped, up to 5 cm long and 4 cm wide (2.0 in × 1.6 in), weighing approximately 20 g. The thin, tough skin is green when immature, ripening to red or pink-red, and is smooth or covered with small, sharp, roughly-textured protuberances. The rind is inedible but easily removed to expose a layer of translucent white flesh with a floral aroma and a sweet flavor. The skin turns brown and dry when left out after harvesting. The fleshy, edible portion of the fruit is an aril, surrounding one dark brown inedible seed that is 1 to 3.3 cm long and 0.6 to 1.2 cm wide (0.39–1.30 by 0.24–0.47 in). Some cultivars produce a high percentage of fruits with shriveled aborted seeds known as 'chicken tongues'. These fruits typically have a higher price, due to having more edible flesh. Since the floral flavor is lost in the process of canning, the fruit is usually eaten fresh.

Flavor and aroma The edible aril of the lychee is juicy and translucent, with a sweet, mildly tart flavor and a distinctive floral aroma often described as rose-like. Its sweetness is primarily due to sucrose, glucose, and fructose, while malic and citric acids provide acidity. Aroma-active compounds in the flesh include the monoterpenes linalool, geraniol, nerol, limonene, and cis-rose oxide, which contribute rose-like and citrus-like notes, as well as furaneol (sweet, caramel-like), methional (cooked-potato nuance), and sulfur volatiles such as dimethyl trisulfide.

History

Cultivation of lychees began in the regions of southern China (going back to 1059 A.D.), Malaysia, and northern Vietnam. Unofficial records in China refer to lychees as far back as 2000 BC. Wild trees still grow in parts of southern China and on Hainan Island. The fruit was a delicacy in the Chinese Imperial Court. In the 1st century during the Han dynasty, fresh lychees were a popular tribute item, and in such demand at the Imperial Court that a special courier service with fast horses would bring the fresh fruit from Guangdong. There was great demand for lychee in the Song Dynasty (960-1279), according to Cai Xiang in his Li chi pu (Treatise on Lychees). It was also the favorite fruit of Emperor Li Longji's (Xuanzong) favored concubine Yang Yuhuan (Yang Guifei). The emperor had the fruit delivered at great expense to the capital. The lychee attracted the attention of European travelers, such as the Spanish bishop, explorer, and sinologist Juan González de Mendoza in his History of the Great and Mighty Kingdom of China (1585; English translation 1588), based on the reports of Spanish friars who had visited China in the 1570s and given the fruit high praise:

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