In food systems, one of the most important properties that truly differentiates carrageenan from other hydrocolloids is its ability to complex or interact with proteins. In milk protein systems, at peripheral locations on the casein micelle there is a concentration of positive charges. This positive electrostatic charge attracts the negatively-charged sulfate groups of the carrageenan molecule to form linkages among the dispersed casein micelles as illustrated in Figure 14 . This reaction, in combination with the normal water gelling capabilities of carrageenan, can increase the gel strength about 10-fold.
Carrageenan’s ability to complex with milk proteins,combined with its water gelling properties enhances carrageenan’s functionality, e.g. increased gel potential. For this reason carrageenan will form a weak thixotropic gel structure which will suspend cocoa in chocolate milk at 0.02% and form milk gels, such as flans, at 0.20%.