Friday, August 05, 2022

History of gelling agent: Agar

Gelatin was the first gelling agent to be discovered but it soon paved the way for agar, which has far superior material qualities.

The most widely used gelling agent in the microbiological field is agar-agar, which has been widely distributed since 1905. Agar has its origins in Japan in 1658. It was discovered by Mino Tarōzaemon, an innkeeper in current Fushimi-ku, Kyoto

It was introduced first in the Far East and later in the rest of agarophyte seaweed producing countries. Its use was introduced in Europe in 1859 and it was being used in bacteriological culture media in 1882.

Agar allows microorganisms to be incubated at temperatures of up to 37° C because of its high gelation temperature; the high transparency facilitates the differentiation of colonies; the high firmness and low adhesiveness favors the distribution of microorganisms on the media’s surface.

In 1881 Robert Koch demonstrated a new technique at the International Medical Congress in London. Koch had recognized the difficulties of using broth media for isolation of pure cultures and had looked for solid media alternatives. Solid media, which is achieved by the addition of gelling agents to the liquid broth, is more suited for the separation and isolation of microorganisms than liquid media. Gelatin was used to obtain the first solid media in 1881 by Robert Koch. He paved the way to culture-based diagnosis of tuberculosis.

Fanny Angelina Eilshemius,in 1881, proposed the use of agar as an alternative to gelatin to prepare solid culture. Fannie, wife of Walther Hesse, was working in Koch’s laboratory as her husband’s technician and had previously used agar to prepare fruit jellies after hearing about its gelling properties from friends.

Later, European traders saw the possibilities of this product in the food industry, and began to expand its use throughout Europe.
History of gelling agent: Agar