What is agar made of
Agar (Malay.) too Agar AgarCalled agartang, Japanese isinglass, edging (Japanese) or Chinese or Japanese gelatine, like carrageenan it is a polysaccharide (more precisely galactose polymer) that can form jelly. The basic units of agar are agarose and sulfated agaropectin.
Agar is made from the cell walls of some types of algae (especially red algae, such as Gracilaria-, Gelidiopsis-, Gelidium-, Hypnea- and SphaerococcusSpecies), mainly from East Asia.
Agar is tasteless and indigestible. It is a very good gelling agent that is independent of the surrounding medium. A concentration of 1% dissolved in hot water is enough for a good gel, half a teaspoon corresponds to about four sheets of gelatine. Agar gel becomes liquid at 95 degrees Celsius, which is why the gel is stable even at higher temperatures than gelatine gels, and solidifies at 45 degrees Celsius, which means that thermolabile substances can be added before it solidifies. The main component of the agar is the agarose.
Areas of application
In food technology, agar (in the EU as a food additive number E 406) as a thickener, e.g. B. used in soups, confectionery and ice cream, but relatively seldom because the price is very high. In the household it can be used as a vegan substitute for gelatine. Agar has been used in food preparation in Japan and China since the 17th century. It is an integral part of the kitchen in Southeast Asia. There it is used to prepare a wide variety of desserts. Gelatine is completely unknown there.
In microbiology, culture media for microorganisms are almost invariably solidified with agar instead of gelatin, because agar is more resistant than gelatin to the high temperatures used during sterilization, gelatin gels are liquefied at higher incubation temperatures, and because some microorganisms can digest gelatin. The German microbiologist Walther Hesse was the first to use agar culture media to grow bacteria and published this in 1884 (About the quantitative determination of the microorganisms contained in the air. In: Messages from the Imperial Health Office. Vol. 2, 1884, pp. 182-207). The idea came from his wife Fanny Angelina Hesse, who had been using agar to make fruit jelly since a Dutch neighbor who immigrated from Java had pointed it out to her.
Agar in gel form is also used as a substrate for various plants to be grown in laboratories.
Due to its indigestibility, agar is also used as a laxative (in higher doses than in food). In Indonesia, agar-agar is said to have positive effects against diabetes mellitus and heart diseases.
Sources of supply
Agar is available at low prices in large supermarkets, health food stores, health food stores and Asian grocery stores. Agar in its pure form can be purchased in pharmacies at high prices.
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