One member of the casein family is especially influential in these gatherings. That is kappa-casein, which caps the micelles once they reach a certain size, prevents them from growing larger, and keeps them dispersed and separate. One end of the capping-casein molecule extends from the micelle out into the surrounding liquid, and forms a “hairy layer” with a negative electrical charge that repels other micelles.
From the book On Food and Cooking (2nd edition) by Harold McGee. © 2004 Harold McGee. By permission of Scribner, a division of Simon & Schuster, Inc.