卡拉胶（Carrageenan，CAS 9000-07-1），又称鹿角菜胶、角叉菜胶、爱尔兰苔菜胶，是从海洋红藻（包括角叉菜属、麒麟菜属、杉藻属及沙菜属等）提取的多糖的统称，是多种物质的混合物，有ι(Iota)、κ(Kappa)、λ(Lambda)、μ(mu)四种。卡拉胶的名字来源于爱尔兰苔菜（Chondrus crispus，也称角叉菜），角叉菜在爱尔兰语称为 carraigín。

当用于食品时，在包装的卡拉胶以欧洲联盟的E编码E407（藻酸盐）表示。

Carrageenans or carrageenins (/ˌkærəˈɡiːnənz/ KARR-ə-GHEE-nənz from Irish carraigín, "little rock") are a family of linear sulphated polysaccharides that are extracted from red edible seaweeds. They are widely used in the food industry, for their gelling, thickening, and stabilizing properties. Their main application is in dairy and meat products, due to their strong binding to food proteins. There are three main varieties of carrageenan, which differ in their degree of sulphation. Kappa-carrageenan has one sulphate group per disaccharide. Iota-carrageenan has two sulphates per disaccharide. Lambda carrageenan has three sulphates per disaccharide.