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Agar vs. Alginate: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Published on January 23, 2024
Agar is a gelatinous substance derived from red algae used as a stabilizer and medium in food and scientific applications, while alginate, extracted from brown algae, is used for its thickening, gelling, and stabilizing properties.

Key Differences

Agar is obtained from red algae and is mainly composed of agarose and agaropectin. Alginate, derived from brown algae, is a polysaccharide composed of mannuronic and guluronic acid units.
Agar forms firm, brittle gels and is used as a vegetarian gelatin substitute in cooking and baking. Alginate forms softer gels and is often used in food as a thickening agent, especially in jellies and ice creams.
In biotechnology, agar is widely used as a culture medium for microorganisms and plant tissues. Alginate has found applications in wound dressings and dental impressions due to its biocompatibility and moldability.
Agar gels upon cooling after heating, making it useful in culinary applications for setting desserts. Alginate requires the presence of divalent cations like calcium to form gels, a process utilized in molecular gastronomy for spherification.
Both agar and alginate are sustainable products, as they are derived from renewable seaweed sources. However, the harvesting practices and processing methods can impact their overall environmental footprint.

Comparison Chart


Red algae
Brown algae

Gel Texture

Firm and brittle
Soft and flexible

Primary Use

Gelatin substitute, culture medium
Thickening agent, spherification

Gelling Mechanism

Gels upon cooling
Requires divalent cations to gel

Key Composition

Agarose and agaropectin
Mannuronic and guluronic acid

Agar and Alginate Definitions


Agar solidifies at room temperature.
After boiling, the agar mixture will set once cooled.


Alginate is used as a thickener and stabilizer in foods.
Ice cream manufacturers add alginate to improve texture.


Agar is a key component in microbiological media.
Scientists use agar plates for microbial growth studies.


Alginate is a polysaccharide extracted from brown algae.
Alginate is often used in the production of dental molds.


Agar is a gelatinous substance derived from red algae.
Agar is used in petri dishes to grow bacteria cultures.


Alginate is biodegradable and biocompatible.
Alginate dressings are effective for treating wounds.


Agar serves as a vegetarian gelatin substitute.
She used agar to make vegan jelly.


Alginate forms gels in the presence of calcium ions.
Chefs use alginate for spherification in molecular gastronomy.


Agar is used in culinary applications for its gelling properties.
Agar can be used to thicken soups and sauces.


Alginate has industrial applications in textile printing.
In textile printing, alginate is used as a thickening agent for dyes.


A gelatinous material derived from certain marine algae. It is used as a base for bacterial culture media and as a stabilizer and thickener in many food products.


A salt of alginic acid, widely used as a thickening or gelling agent.


A culture medium containing this material.


(biochemistry) Any salt or ester of alginic acid.


A gelatinous material obtained from red algae, especially Gracilaria species, used as a bacterial culture medium, in electrophoresis and as a food additive.


A culture medium based on this material.




Common shortened form of agar-agar{2}.


Any culture medium that uses agar as the gelling agent; - used especially with a modifying prefix, as, EMB agar. The term is applied both to the dehydrated medium powder containing agar and to the gelatinous medium prepared from it.


Any culture medium that uses agar as the gelling agent


A colloidal extract of algae; used especially in culture media and as a gelling agent in foods


What is the main difference in texture between agar and alginate gels?

Agar forms firmer gels, while alginate gels are softer and more flexible.

Does agar have a flavor?

Agar is flavorless, making it versatile in various dishes.

Can alginate be digested?

Alginate is not digestible and passes through the digestive system.

Is agar vegan?

Yes, agar is a vegan alternative to gelatin.

What makes alginate ideal for dental impressions?

Alginate's moldability and non-toxic nature make it ideal for dental impressions.

Is agar suitable for all types of bacterial cultures?

Agar is suitable for most bacterial cultures but not for fungi.

Can alginate be used for wound healing?

Yes, alginate is used in wound dressings due to its absorbent properties.

How much agar is needed to set a liquid?

Typically, 1-2% of agar is enough to gel most liquids.

Can alginate be used in vegan cooking?

Yes, alginate is plant-based and suitable for vegan diets.

Can alginate be used in gluten-free cooking?

Yes, alginate is gluten-free and suitable for such diets.

Does agar have a shelf life?

Agar, when stored properly, has a long shelf life.

How is agar extracted from red algae?

Agar is extracted through boiling and filtering red algae.

Is alginate environmentally friendly?

Alginate is generally eco-friendly as it is derived from renewable seaweed.

Does alginate affect the flavor of food?

Alginate is typically flavorless and does not alter the taste of food.

Is agar readily available in grocery stores?

Agar can be found in health food stores and some grocery stores.

Does agar provide any nutritional benefits?

Agar is low in calories and high in fiber.

Does agar need refrigeration to set?

No, agar sets at room temperature, unlike gelatin.

Can alginate be used in dairy products?

Yes, alginate is often used as a stabilizer in dairy products.

Are there any allergens in alginate?

Alginate is generally free of common allergens.

Can agar be used in high-heat cooking?

Agar maintains its gelling properties even after being heated.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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