Whey protein eventually expires due to the small traces of dairy in the product, according to WeightTraining.com. Whey protein products list the expiration dates on the containers. The taste and potency of whey protein deteriorate over time, but most whey protein products have a long shelf life.
Manufacturers produce whey protein as a derivative of cow milk and a by-product of cheese, states WeghtTraining.com. Milk is pasteurized and evaluated prior to separating the casein protein from the liquid whey. The liquid whey undergoes a series of filtering processes that separate lactose and other ingredients from the liquid whey. It's left to dry to create whey protein powder, and then manufacturers package and ship out the products to vendors for sale.