Siraitia grosvenorii is an herbaceous perennial vine native to southern People s Republic of China and Northern Thailand and best known for its fruit, the luo han guo (traditional Chinese: 羅漢果/simplified Chinese: 羅漢果; pinyin: luóhàn guǒ; literally 'arhat fruit' or monk s fruit). It is one of four species in the genus Siraitia. Botanical synonyms include Momordica grosvenorii and Thladiantha grosvenorii. The fruit is one of several that have been called longevity fruit.
The other species of the genus Siraitia are: S. siamensis from Thailand, S. sikkimensis and S. silomaradjae from India, and S. taiwaniana from the Republic of China (Taiwan).
The vine grows to 3 to 5 m long, climbing over other plants by means of tendrils which twine round anything they touch. The narrow, heart-shaped leaves are 10–20 cm long. The fruit is globose, 5–7 cm in diameter, and contains a sweet, fleshy, edible pulp and numerous seeds.
The fruit extract is nearly 300 times sweeter than sugar and has been used as a natural sweetener in China for nearly a millennium due to its flavor and lack of food energy, only 2.3 kcal/g (9.6 kJ/g). It has also been used in traditional Chinese medicine.
It is grown primarily in the southwestern Chinese province of Guangxi (mostly in the mountains of Guilin), as well as in Guangdong, Guizhou, Hunan, and Jiangxi. These mountains lend the plants shadows and often are surrounded by mists; because of this the plants are protected from the worst of the sun. Nonetheless, the climate in this southern province is warm. The plant is rarely found in the wild and has hence been cultivated for hundreds of years.
Records as early as 1813 mention the cultivation of this plant in the Guangxi province. At present, the Guilin mountains harbor a plantation of 16 square kilometers with a yearly output of about 10,000 fruits. Most of the plantations are located in Yongfu County and Lingui County, which in China are renowned for the extraordinary number of centenarians. This is usually attributed to the consumption of this fruit and the unspoiled nature. The inhabitants themselves, however, are of the opinion that the reason lies in their calm lifestyle and simple nutrition.
Longjiang town ('Dragon River') in Yongfu County has acquired the name 'home of the Chinese luohanguo fruit'; a number of companies specialised in making luohanguo extracts and finished products have been set up in the area. The Yongfu Pharmaceutical Factory is the oldest of these.
The plant is most prized for its sweet fruits, which are used for medicinal purposes, and as a sweetener.The fruits are generally sold in dried form, and traditionally used in herbal tea or soup. They are used for respiratory ailments, sore throats and reputed to aid longevity.
The best way to describe the medicinal use of luohan guo in southern China during the 20th century can be found in the book written by Dai and Liu. It was written in Chinese in 1982 and translated into English in 1986. Here is their description:
The dried fruit may be bought in a market. The surface of the fruit is round and smooth, it has a yellow-brownish or green-brownish colour, and is covered by fine hairs. The fruit has a hard but thin shell. Inside, one finds a partially dried, soft substance which contains the juice and a large quantity of seeds. All components are very sweet. Their nature is cool and not toxic. The fruit can act as a remedy for sun stroke, wet the lungs, remove phlegm, stop cough and aid defecation.
Heat stroke and thirst.Take a fruit, break it open and pour hot water on it to make an infusion. Drink the infusion in place of tea.
Acute or chronic infection of the larynx (aphonia). Take the halves of a fruit and 3 to 5 sterculia seeds, cover this with water and leave it to boil. Swallow very slowly.
Chronic cough. Take a piece of the fruit, cover it with water and leave it to boil. Drink the resulting liquid twice daily.
Constipation due to old age. Take two fruits and, using only the soft parts and seeds, divide it into pieces. Cover these pieces with water, boil it, and drink the liquid before going to bed.
Diabetes.Take an appropriate amount of fruit squash or boil it so as to get concentrated juice. Use this as a substitute for sugar in your nutrition..
Luohan guo is harvested in the form of a round green fruit, which becomes brown on drying. It is rarely used in its fresh form, as it is hard to store. Furthermore, it develops a rotten taste on fermentation, which adds to the unwanted flavours already present.
Thus the fruits are usually dried before further use and are sold in precisely this fashion in Chinese herbal shops. The fruits are slowly dried in ovens, which preserves it and removes most of the unwanted aromas. However, this technique also leads to the formation of several bitter and astringent aromas. This limits the use of the dried fruits and extracts to the preparation of diluted tea, soup, and as a sweetener for products that would usually have sugar or honey added to them.