How is whey protein made?

Whey protein is a co-product of the cheese making process. The steps generally involved in making whey protein isolate (WPI) are as follows:

Fresh milk is tested, approved for quality and pasteurized.
The casein, or "curd", and a portion of the milk-fat are separated out to make cheese.
The remaining liquid whey goes through a series of fine, specialty filters separating the whey protein from the lactose and other ingredients in the liquid.
Concentrated liquid whey enters an ion exchange tower to further concentrate and purify the whey protein. Ion exchange is a gentle process and does not denature, or "break down", the whey protein.
The product then enters a drying tower to remove water.
Once complete the final product (pure whey protein isolate powder) is packaged for use.