MPC contains 80% casein and 20% whey proteins while WPC contains solely whey proteins. Casein and whey proteins react very differently under various conditions so it is important to understand how each protein will react in your application.

Caseins are generally good at fat emulsification, foaming amd water binding, and have good heat stability as long as the pH of the application they are used in is above six.  When the pH decreases below six, caseins will form acid gels, which is essentially the process that happens during the fermentation of milk into yogurt and cheese.   

Whey proteins are known for their foaming ability, gelling properties, high solubility over a wide pH range and heat sensitivity. Unlike casein, whey proteins will denature upon heating starting at about 145 degrees Fahrenheit and the proteins will eventually form a gel at a high enough concentration (about 7% protein). Whey proteins do not form acid gels like caseins, which is a key difference to consider when choosing a dairy protein ingredient for a yogurt application.