Carrageenans 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 stabilising 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 and forms strong, rigid gels in the presence of potassium ions; it reacts with dairy proteins. It is sourced mainly from Kappaphycus alvarezii.
- Iota-carrageenan has two sulphates per disaccharide and forms soft gels in the presence of calcium ions. It is produced mainly from Eucheuma denticulatum.
- Lambda carrageenan has three sulphates per disaccharide. It does not gel, and is used to thicken dairy products.
Carrageenan is a vegetarian and vegan alternative to gelatine in some applications, although it cannot replace gelatine in confectionery such as jelly beans.
In molecular gastronomy it is used as follows:
- Desserts, ice cream, cream, milkshakes, salad dressings, sweetened condensed milk, and sauces: gel to increase viscosity
- Pâtés and processed meats such as ham: substitute for fat, increase water retention, and increase volume, or make them easier to slice
- Soya milk and other plant milks: used to thicken, in an attempt to emulate the consistency of whole milk
- Vegetarian hot dogs