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**1. Overview of Agar**

– Etymology: Agar comes from agar-agar, the Malay name for red algae.
– Also known as Kanten (Japanese: 寒天) and commonly referred to as China grass or Ceylon moss.
– Chemical Composition: Agar consists of agarose and agaropectin, with agarose making up about 70% and agaropectin about 30%.
– Physical Properties: Agar solidifies to form a gel at 32–42°C, melts at 85°C, and is suitable for scientific applications requiring incubation at 37°C.
– History: Agar was discovered as a food additive in Japan in 1658, first chemically analyzed in 1859, and used in microbiology media from the late 19th century.

**2. Culinary Uses of Agar**

– Agar-agar is used as a natural vegetable gelatin in making jellies, puddings, and custards.
– Contains approximately 80% dietary fiber and is used in fad diets for its bulking quality.
– Widely used in Taiwanese bubble tea and other culinary applications like fruitcakes, jams, and marmalades.
– Offers superior gelling properties compared to gelatin and is a strengthening ingredient in soufflés and custards.
– Traditional candies in Mexico are made from Agar gelatin.

**3. Applications of Agar in Microbiology**

Agar plate is used for bacterial and fungal culture due to its indigestible nature for many organisms.
– Different types of agar support the growth of various microorganisms, and agar plates can be selective to promote the growth of specific bacteria.
Agar or agarose medium is used in motility assays to measure microorganism motility, and under-agarose cell migration assays can identify motile species.

**4. Diverse Uses of Agar**

Agar is used in dentistry as an impression material, in histopathology processing to secure tissue specimens, and in electrochemistry for salt bridges and gel plugs.
– Also used in formicariums, modeling clay, and organic farming as a biofertilizer component.
– Commercially, agar is used in bacteriological plates, food applications, and as a substitute in various industries.

**5. Production, Substitutes, and Research Applications of Agar**

Agar is derived from seaweed, harvested from red algae, and processed in major agar-producing countries like Japan, China, and South Korea.
– Plant-based alternatives like carrageenan, gelatin, xanthan gum, pectin, and arrowroot powder can substitute agar.
– In research, agar is essential for medical research, molecular biology techniques, cloning of genes, selective media, and synthetic biology applications.

Agar (Wikipedia)

Agar (/ˈɡɑːr/ or /ˈɑːɡər/), 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). As found in nature, agar is a mixture of two components, the linear polysaccharide agarose and a heterogeneous mixture of smaller molecules called agaropectin. It forms the supporting structure in the cell walls of certain species of algae and is released on boiling. These algae are known as agarophytes, belonging to the Rhodophyta (red algae) phylum. The processing of food-grade agar removes the agaropectin, and the commercial product is essentially pure agarose.

Green tea flavored yōkan, a popular Japanese red bean jelly made from agar
A blood agar plate used to culture bacteria and diagnose infection

Agar has been used as an ingredient in desserts throughout Asia and also as a solid substrate to contain culture media for microbiological work. Agar can be used as a laxative; an appetite suppressant; a vegan 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.

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