This production centered on Japan, which produced most of the world's agar until World War II. With its newfound use in microbiology, agar production quickly increased. Agar quickly supplanted gelatin as the base of microbiological media, due to its higher melting temperature, allowing microbes to be grown at higher temperatures without the media liquefying. Agar was first described for use in microbiology in 1882 by the German microbiologist Walther Hesse, an assistant working in Robert Koch's laboratory, on the suggestion of his wife Fanny Hesse. īeginning in the late 19th century, agar began to be used as a solid medium for growing various microbes. Īgar was first subjected to chemical analysis in 1859 by the French chemist Anselme Payen, who had obtained agar from the marine algae Gelidium corneum. Over the following centuries, agar became a common gelling agent in several Southeast Asian cuisines. Ogonori, the most common red alga used to make agarĪgar may have been discovered in Japan in 1658 by Mino Tarōzaemon ( 美濃太郎左衞門), an innkeeper in current Fushimi-ku, Kyoto who, according to legend, was said to have discarded surplus seaweed soup ( Tokoroten) and noticed that it gelled later after a winter night's freezing. Agar can be used as a laxative, an appetite suppressant, a vegetarian substitute for gelatin, a thickener for soups, in fruit preserves, ice cream, and other desserts, as a clarifying agent in brewing, and for sizing paper and fabrics. Īgar has been used as an ingredient in desserts throughout Asia and also as a solid substrate to contain culture media for microbiological work.

These algae are known as agarophytes, belonging to the Rhodophyta (red algae) phylum. It forms the supporting structure in the cell walls of certain species of algae and is released on boiling. Īgar is a mixture of two components, the linear polysaccharide agarose and a heterogeneous mixture of smaller molecules called agaropectin. A blood agar plate used to culture bacteria and diagnose infectionĪgar ( / ˈ eɪ ɡ ɑːr/ or / ˈ ɑː ɡ ər/), or agar-agar, is a jelly-like substance consisting of polysaccharides obtained from the cell walls of some species of red algae, primarily from ogonori ( Gracilaria) and 'tengusa' ( Gelidiaceae).

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