What Is Whey?

A Guide to Buying, Using, and Storing Whey

what is whey

The Spruce Eats / Lindsay Kreighbaum

While many Americans can recite the story of Little Miss Muffet eating her curds and whey, most would be hard-pressed to list a single home-kitchen use for whey, a byproduct of cheese-making and a main ingredient in commercial protein powders and bars.

Much of the whey resulting from commercial production of cheese and other dairy products such as yogurt ends up as animal feed or going down the drain. But creative chefs have been finding new uses for the nutrient-packed, flavorful liquid.

What Is Whey?

Whey (pronounced WAY) is one of the two main proteins in milk. It's the cloudy, yellowish liquid expelled from cheese curds during the cheese-making process and from straining fresh yogurt to thicken it. Whey can be either acidic, like that from yogurt and soft cheeses such as cottage or mozzarella, or sweet, which comes from harder cheeses produced with rennet, such as cheddar and Swiss.

In Italian, ricotta means "recooked," a fitting name for a cheese traditionally made from the whey that remains after another cheese has already been made. Italian ricotta cheese usually uses whey from sheep's milk, while American ricotta cheese typically uses whey from cow's milk.

How to Use Whey

Although whey largely fell out of use in the country when large-scale farming and factory production made individual family farms obsolete, it's been experiencing a bit of a resurgence, first as a supplement among health-food advocates and now within the general population.

You can use commercially purchased powdered sweet whey as a protein booster in smoothies and other blended drinks, pancakes, homemade energy bars, and even added to soups and stews. Depending on the volume of liquid whey you have available, you can use acidic whey in place of water or milk in savory recipes, or as the liquid ingredient in breads and pastries. You can add it to dressings and marinades, boil pasta or rice in it, and soak grains overnight so they cook more quickly. You can even add it to a cocktail or drink it straight over ice.

What Does It Taste Like?

Unflavored fresh whey tastes a bit like plain yogurt—just very slightly sour with a real creaminess, despite its lack of any cream. Powdered supplements come in many flavors, such as vanilla, chocolate, coffee, banana, and berry.

Recipes With Whey

To get your hands on some fresh whey, try making cheese at home. In general, a pound of soft cheese such as mozzarella or goat cheese, made from a gallon of fresh milk, yields 9 pounds of whey. If you make homemade yogurt and drain it in cheesecloth to thicken it, you can use the resulting "yogurt whey" in the same manner.

Where to Buy Whey

You can purchase powdered whey, both flavored and plain, for use as a protein supplement in most health food and grocery stores. It's also available online, in the supplements section of many drugstores, and at gyms around the country. Most of the sweet whey resulting from rennet-based cheese production ends up as protein powder.

Fresh acidic whey is much more difficult to come by, unless you produce your own by making cheese or yogurt at home. You could find a small-scale local producer and offer to take some off their hands; acidic whey can disrupt aquatic ecosystems, so strict laws regulate its disposal.


Store dried whey as you would most any powdered product, in an airtight container protected from heat, light, and moisture. Check the package for an expiration or best-by date, but in general, commercial whey supplements last for up to two years from the date of packaging.

Fresh liquid whey should be kept refrigerated in a tightly sealed glass container; properly stored, it has a shelf life of up to six months.

what is whey
The Spruce Eats / Hugo Lin