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Agar

Agar, also called agar-agar, is a jelly-like polysaccharide obtained from certain species of red algae.

By Ethan Anderson| Reviewed by Olivia Bennett, Standards & Fact-Checking Lead| Updated July 26, 2026|2 min read| Fact-checked

Agar, also called agar-agar, is a jelly-like polysaccharide obtained from certain species of red algae. It is widely used as a gelling, thickening, and stabilizing agent in food, and as a solidifying medium in microbiology and other laboratory work.

Definition

Agar is a gelatin-like substance made from red algae. It consists mainly of polysaccharides, including agarose and agaropectin. The substance is valued for its gelling properties.

Uses

Agar is used in food preparation as a thickener, stabilizer, and vegetarian gelatin substitute. It is also widely used in microbiology as a solid medium for growing microorganisms.

Source and production

Commercial agar is extracted from certain red algae, especially species in the genera Gelidium and Gracilaria. The extracted material is purified and sold in dry forms such as powder, flakes, or bricks.

Properties

Agar is translucent, forms firm gels, and is more heat-stable than gelatin in many applications. These properties make it useful in both culinary and scientific settings.

Key facts

  • Agar is derived from the cell walls of certain red algae.
  • It is best known for its ability to form gels and remain firm at room temperature.
  • In food, it is used in desserts, confections, soups, and other processed products.
  • In laboratories, agar is a standard base for bacteriological culture media.
  • It is sold in several forms, including powder, flakes, and bricks.
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Canadian context

Agar is relevant to Canadian food manufacturing, culinary use, and laboratory science, where it is used as a vegetarian gelling agent and as a microbiological culture medium.

Frequently asked questions

What is agar agar?
Agar agar is another name for agar, a jelly-like substance made from red algae and used mainly as a gelling agent.
What is agar used for?
It is used to thicken and stabilize foods and to make culture media for growing bacteria and other microorganisms.
Where does agar come from?
It is extracted from the cell walls of certain red algae, especially Gelidium and Gracilaria.
Is agar the same as gelatin?
No. Agar is plant-based and comes from algae, while gelatin is usually animal-derived. Both can gel liquids, but they have different properties.
In what forms is agar sold?
Agar is commonly sold as powder, flakes, or bricks.

References

  1. Wikipedia — https://en.wikipedia.org/wiki/Agar
    Supports: General definition, source from red algae, and common forms
  2. Encyclopaedia Britannica — https://www.britannica.com/topic/agar-seaweed-product
    Supports: Uses in food and laboratory media, source algae genera, and commercial forms
  3. Merriam-Webster — https://www.merriam-webster.com/dictionary/agar
    Supports: Definition as a gelatinous extract from red algae and use as a food gelling agent
  4. Cambridge Dictionary — https://dictionary.cambridge.org/dictionary/english/agar
    Supports: General definition and use in scientific work and thickening liquids