Carrageenans (E407)

Application
Carrageenans (E407) are widely used as gelling agents, thickeners and stabilisers.  The addition of various ions or Locust Bean Gum can be used to modify the texture. They can be found in dairy products, beverages, meat products, water gels and powdered desserts. When used as gelling agents in water, they give a wide variety of textures from firm to weak and from elastic to brittle.
Carrageenans are used as stabilisers for foams, ice cream, condensed milk, cream and salad dressings.Due to their protein reactivity, carrageenans produce very economical milk gels. Weak, semi-gelled systems can be used to stabilise chocolate milk, giving mouth feel and cocoa suspension. Cold water-soluble types of carrageenan can be used in instant chocolate milk powders to provide similar properties.
Properties
Carrageenans are large, highly flexible molecules which curl forming helical structures. This gives them the ability to form a variety of different gels at room temperature. They are widely used in the food industry as thickening and stabilising agents. A particular advantage is that they are thixotropic-they thin under shear stress and recover their viscosity once the stress is removed. This means that they are easy to pump but stiffen again afterwards.
Kappa carrageenan is potassium-sensitive and will form strong brittle, thermo-reversible gels in the presence of potassium ions. Calcium and most polyvalent ions will induce gelation to a lesser extent, while the sodium salt is non-gelling and cold water-soluble. All other salts of Kappa carrageenan need to be heated above 50°C, generally to 80°C, to ensure complete dissolution. The gels are generally clear but calcium ions product slight cloudiness. Kappa carrageenan gels do exhibit some syneresis, and are not freeze/thaw stable. Kappa carrageenan will produce strong milk gels at very low levels.
Iota carrageenan forms transparent elastic thermo-reversible gels in the presence of calcium ions. Without the ions, considerable thickening occurs. All salts of iota carrageenan are soluble in cold water and milk and are freeze/thaw stable. The gels do not exhibit syneresis.
Lambda carrageenan does not gel in water or milk but it produces considerable thickening in milk and will stabilise both water and milk systems. It is cold water-soluble, thickening immediately to give a clear viscous solution.
The above three types of carageenan are usually blended and many of the available grades contain various food additives to alter the physical properties for specific uses. In particular, locust bean gum is used to modify Kappa carrageenan, increasing the elasticity, cohesion and breaking strength of the gel.