County and Lingui County. Longjiang Town 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. Traditional processing 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 when fresh. Thus, the fruits are usually dried before further use and are sold in this fashion in Chinese herbal shops. The fruits are dried slowly in ovens, preserving them and removing most of the unwanted aromas. However, this technique also leads to the formation of several bitter and astringent flavors. 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. Commercial manufacturing The process for the manufacture of a useful sweetener from luo han guo was patented in 1995 by Procter & Gamble. The patent states that luo han guo has many interfering flavors, which render it useless for general applications, and describes a process to remove them. The offending compounds are sulfur-containing volatile substances such as hydrogen disulfide, methional, methionol, dimethylsulfide, and methylmercaptan, which are formed from amino acids that contain sulfur, such as methionine, S-methylmethionine, cystine, and cysteine. Sweetening agent The sweet taste of the fruit comes mainly from mogrosides, a group of triterpene glycosides that make up about 1% of the flesh of the fresh fruit. Through solvent extraction, a powder containing 80% mogrosides can be obtained, the main one being mogroside-5 (esgoside). Other similar agents in the fruit are siamenoside and neomogroside. In this process, the peel and seeds are removed, and the pulped fruit is made into a fruit concentrate or puree. Additional juice may be extracted from the remaining pulp by hot water. The juice is homogenized, acidified slightly to prevent gelling and improve the flavor, then treated with pectinase or other enzymes to break down the pectin. Most of the off-flavor agents are then removed with ion-exchange resins, such as sulfonated polystyrene-divinylbenzene copolymer or polyacrylic acid. Alternatively, the off-flavors can be adsorbed by agents like charcoal or bentonite, which are removed by filtration; or precipitated with gelatin or other