There are two main ingredients in milk protein, they are casein and whey. Whey is produced mostly from the production of cheese. Milk is treated to cause a shift in pH and the casein coagulates and separates, and raw whey is left un-curded on top of the casein. It’s then collected and undergoes various processing steps. These processing steps are what determines the quality of the whey protein end product.
During the processing, fat and lactose are filtered out to make a lower fat, lower carbohydrate, and higher concentrated protein powder. The protein content can range from 35% to 95% whey protein. Obviously, the higher the protein concentration, the more processing (filtering) is needed which adds to the cost. Generally, when the protein level reaches >90% concentration, it’s considered WPI (whey protein isolate).
With all of the different terms associated with protein supplements, it’s not difficult to understand why we get confused. When talking about whey proteins, for example, the term ion exchange is common, but what does it really mean? Ion exchange is one method used to produce protein supplements. This is a process that separates proteins on the basis of their electrical charge. Various solvents are used to create an attractive charge on the proteins, which causes them to migrate toward oppositely charged resin beads in the reaction vessel. The protein can then be removed from the resin beads by reversing the charge to result in a “highly purified” whey protein isolate (WPI).