Cookbook:Agar

Agar, or agar agar, is a gelatinous substance derived from seaweed. In cooking, it is chiefly used as an ingredient in desserts throughout Japan.

Characteristics
Agar is a carbohydrate-type thickener made of long chains of the sugar galactose. Commercially it is derived primarily from Gelidium amansii, and it creates a strong gel with no flavor.

On average, agar is about 8 times stronger than gelatin, which means it takes 8 times less agar than gelatin to set a product to the same degree. Unlike gelatin, agar both sets and melts at a higher temperature—after dissolving in boiling liquid, agar sets at 95°F (35°C) and doesn't melt again until heated to 185°F (85°C). This makes it very stable, but it isn't as soft and melt-in-the-mouth, which can sometimes create a "crumbly" texture.

Acids decrease agar's gelling strength, and more may be needed to make a dish set. Unfortunately, agar doesn't work to stabilize whipped and aerated mixtures, so it can't be used effectively in mousses, marshmallow, etc.

Varieties
Agar can come in multiple forms for culinary use. It is most commonly available in powdered or strand form. When in strands, it is often referred to as "China grass".

Use
Agar can be used as a laxative, a gelatin substitute, a thickener for soups, in jellies, ice cream, and Japanese desserts such as anmitsu. It can also be used as a clarifying agent in brewing.