carrageenan. According to the website of Gourmet World, carrageenan is a kind of hydrophilic colloid, also known as carrageenan, agar, carrageenan and carrageenan, because carrageenan is a hydrophilic colloid extracted from red seaweed such as Eucalyptus, agar and carrageenan, which is usually used to make jelly. Adding carrageenan to cakes can make them feel very moist.