Arhat (Siraitia grosvenorii) Synonyms: Momordica grosvenorii Swingle; Thladiantha grosvenorii (Swingle) C. Jeffrey. Siraitia grosvenorii is a perennial herbaceous climbing plant in the cucurbitaceae family, native to southern China and northern Thailand. The plant is prized for its fruits, the extract of which is almost 300 times sweeter than sugar. In China, monk fruit is used as a natural, low-calorie sweetener for chilled drinks and in traditional Chinese medicine for diabetes and obesity. In English publications, the fruit of the monk is often referred to as luo han guo or lo han kuo (Luo Han Guo), from the Chinese Luohan guǒ, 罗汉果 / 羅漢果. The plant is also called la hán quả, Buddha fruit, monastic fruit or longevity fruit (the latter name is also used for some other plants). Siraitia grosvenorii is named after Gilbert Grosvenor, who, as president of the National Geographic Society, helped fund an expedition in the 1930s to locate the plant in its cultivation.
The vine reaches a length of 3 to 5 meters, "climbing" other plants with tendrils twisting around everything they touch. The plant has narrow, heart-shaped leaves 10-20 cm long. Fruits are round, 5-7 cm in diameter, smooth, yellow-brown or green-brown in color, with stripes extending from the end of the peduncle, with a tough but thin skin covered with fine hairs. The inside of the fruit contains edible pulp, which, after drying, forms a thin, light brown fragile shell about 1 mm thick. The seeds are elongated and almost spherical. Monk fruit is sometimes mistaken for an unrelated species, purple mangosteen. The inside of the fruit is eaten fresh, and the bitter rind is used to make tea. Siraitia grosvenorii is famous for its sweet taste, which can be concentrated from the sap of the plant. The fruit contains 25 to 38% of various carbohydrates, mainly fructose and glucose. The sweetness of the fruit is enhanced by the presence of mogrosides, a group of triterpene glycosides (saponins). Five different mogrosides are numbered I through V; the main component is mogroside V, which is also known as esgoside. The fruit also contains vitamin C.
Seed germination is slow and can take several months. The plant is grown mainly in the far southern Chinese province of Guangxi (mainly in the mountains near Guilin), as well as in the provinces of Guangdong, Guizhou, Hunan and Jiangxi province. Because of the mountains, the plants are shaded and often surrounded by fog, which protects them from the sun. However, the climate in this southern province is warm enough. The plant is rarely found in the wild; it has been specially cultivated for several hundred years. Records dated 1813 mention the cultivation of this plant in Guangxi province. There is currently a 16 km2 (6.2 sq mi) plantation in the Guilin Mountains with an annual production of about 100 million fruits. Most of the plantations are located in Yongfu and Lingui counties. Longyang City in Yongfu County is considered the "home of the Chinese fruit of Luo Han Guo"; a number of companies specializing in the production of Lo Han Guo extracts and finished products from monk fruit were founded in this area. The oldest of these companies is Yongfu Pharmaceutical Factory.
The plant is most prized for its sweet fruits, which are used medicinally and as a sweetener. The fruit is usually sold dried and is traditionally used in herbal teas or soups.
No negative side effects of monk fruit have been reported. The FDA defines the fetus as "generally safe for health." No restrictions were made regarding the consumption of the fruit or its extracts.
The sweet taste of the fruit is provided by mogrosides, a group of triterpene glycosides, which make up about 1% of the pulp of fresh fruits. By solvent extraction, a powder containing 80% mogrosides can be obtained, the main of which is mogroside-5 (esgoside). Other similar substances found in fruits are siamenoside and neomogroside. Recent research suggests that isolated mogrosides have antioxidant properties and possibly limited anti-cancer effects. Mogroside has also been shown to inhibit the induction of the Epstein-Barr virus in vitro. The plant also contains the glycoprotein momogrosvin, which inhibits ribosomal protein synthesis.
Traditional processing methods
Arhat fruits are round and green when picked, and brown when dried. They are rarely used fresh due to storage difficulties. In addition, in the process of fermentation, the fruits acquire a rotten taste, which is superimposed on the unpleasant aromas already present. Thus, the fruit is usually dried and sold dried in Chinese herbal shops. The drying process is carried out over low heat in ovens, thanks to which it is possible to preserve the fruit, removing most of the unpleasant odors. However, this method also produces a bitter and astringent taste. This limits the use of dried fruits and extracts for making teas, soups, and as a sweetener for foods traditionally consumed with sugar or honey.
Procter & Gamble Process
In 1995, Procter & Gamble patented a process for making a healthy sweetener from monk fruit. The patent claims that while monk fruit is very sweet, it contains too many foreign aromas that make it useless to use. The company's patented process focuses on removing foreign odors. Fresh fruits are harvested until they are finally ripe, and then stored for some time so that the process of their processing falls just at the stage of fruit ripeness. The shell and seeds are removed, and the fruit pulp is made into a fruit concentrate or puree, which is then used for further food production. Solvents are used to remove unpleasant odors.
During the Tang Dynasty, the Guilin area was one of the most important places for Buddhist retreats with many temples. The fruit was named after the Arhats (Luohan, 羅漢), Buddhist monks who hoped to achieve enlightenment and liberation through a proper lifestyle and meditation from their point of view. The word "luohan" (羅漢) is a shortened form of the word "āluóhàn" (阿羅漢), which is a very old transliteration of the Indian Sanskrit word "arhat". In early Buddhist traditions, an arhat was a monk who became enlightened. This process was called "attaining the fruits of an arhat" (Sanskrit: arhattaphala). In Chinese, this word was transformed into "Luohan guǒ" (羅漢果, lit. "fruit of Arhat"), which later became the designation for this type of sweet fruit in China. According to Chinese history, the fruit is first mentioned in the records of 13th century monks who used it for food. However, plantation space was limited, and arhat grew mainly on the slopes of the Guangxi and Guangdong mountains, and to a lesser extent in Guizhou, Hunan, Jiangxi and Hainan. Because of this and the difficulties involved in growing it, the fruit did not become part of Chinese traditional medicine, which used the more readily available herbs and plants. Because of this, the fruit is also not mentioned in traditional herbal guides.
Rediscovery of the Arhat in the 20th Century
The first mention of this plant in English occurs in an unpublished manuscript written in 1938 by Professors Groff and Hoh Hin Chung. The fruit was often used as the main ingredient in "chilled drinks, " meaning drinks used in heat, and as a remedy for fevers or other disorders traditionally associated with heat (inflammation), the report says. Then it was known that the juice from the fruit is very sweet. Interviews have confirmed that the fruits have only recently acquired meaning in Chinese history. However, a small group of people seem to have mastered plant cultivation a long time ago and have amassed extensive experience with plant growth, pollination, and climatic requirements. The fruit was brought to the United States at the beginning of the 20th century. Groff mentions that during his visit to the American Department of Agriculture in 1917, botanist Frederick Coville showed him monk fruit purchased from a Chinese store in Washington. The seeds of the fruit, purchased from a Chinese store in San Francisco, were introduced into the botanical description of the species in 1941. The first study of the sweet components of monk fruit is attributed to S.H. Lee, who wrote a report on the plant in English in 1975, and Takemoto, who studied it in the early 1980s in Japan (Takemoto later decided to focus on a similar sweet plant gynostemma). In China, the development of production of products from monk fruit, in particular, concentrated extracts, is still continuing.