Thickening the base imparts a feeling of creaminess to the milk. And yes, this seaweed derived thickener is a major ingredient in less expensive (read: cheap) brands of ice cream.
VegetariansIts origin makes carrageenan a natural for vegetarian products. One historically important variety comes from Chondrus crispus seaweed. It is very often called Irish Moss. It replaces animal based gelatin. Another well known form comes from the seaweed Gigartina stellata (which is called Carrageen Moss).
ChemicallyChemically, the thickener is not simply one substance. It is a whole family of substances, the sulfated¹ polysaccharides². Members of the family are categorized by their structure, which reflects the ability or inability to form gels.
Who May Eat CarrageenanThe most controversial use of this food additive is in baby formula. The U.S. permits its use (why is that not surprising?), whereas the European Union (EU) disallows it.
¹ The sulfur and oxygen containing sulfate group is written –OSO₃
² Polysaccharides are complex compounds consisting of linked sugar molecules. The sugar units are galactose and 3,6-anhydrogalactose.
- FAO: Production, Properties, and Uses of Carrageenan
- Cyber Colloids Ltd: Introduction to Carrageenan Structure