Red algae is added to food in the form of carrageenan and agar extracts: these additives are contained in many foods, including frozen deserts, soups, gravies, salad dressings and dairy products. Carrageenan and agar are similar in physical and chemical composition, although carrageenan is slightly thicker and more viscous. Carrageenan is often used to stabilize shelved food items and refrigerated items such as pudding, chocolate, milk and frostings, while agar is better suited for low temperatures.
Carrageenan adds little flavor to the substances that it comprises. However, it creates a gel-like quality, which binds gelatins, puddings and other mixes. In this form, red algae is added to eggnog, sherbets, instant pudding and creamed soup.
Agar, like carrageenan, is a byproduct of red algae. Agar, however, helps keep items solidified at low temperatures, which makes it ideal for ice cream, popsicles and other frozen items. Agar is relatively inexpensive to produce, which makes it a popular additive for commercial food products. It is sometimes used as a substitute in shelf-stable items, such as breads and pastries, where it replaces gelatin. Agar in this form is used to create mayonnaise, processed cheese, whipped cream, relishes, dairy products, syrups and fruit juices. Some candies and chocolates contain also agar — as do many infant formulas and breakfast cereals.