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Culinary Arts

What Is Whey? Learn About the Uses for Whey and the Difference Between Whey Concentrate and Whey Isolate

Written by MasterClass

Last updated: Oct 10, 2019 • 4 min read

While cheese has been around for thousands of years, there’s one little-known byproduct of cheesemaking that can be used for everything from cooking to gardening: whey.



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What Is Whey?

Whey is one of the two proteins in milk (the other being casein). While normally the two milk proteins remain intermixed when you drink or cook with milk, whey can be isolated from casein during the cheesemaking process, when it is drained from cheese curds as the watery part of milk, usually a yellowish liquid. There are two types of whey:

  • Sweet whey. Sweet whey is the whey produced when cooks use rennet to coagulate cheese. Rennet-coagulated cheeses are usually hard cheeses like cheddar or Swiss.
  • Acid whey (or sour whey). Acid whey is the whey produced from using acid (like lactic acid bacteria) to curdle cheese. This method produces soft cheeses like mozzarella or cottage cheese.

How Is Whey Produced?

Whey is first made by warming milk (cow’s milk, goat’s milk, or sheep’s milk) on the stovetop. Unpasteurized milk works best because it already has the necessary bacteria to begin culturing, but in the United States, milk must be pasteurized, and therefore needs to have bacteria culture added to it at this step.

After the milk has the bacteria, cooks add either powdered rennet or acidic bacteria (such as lactic acid bacteria). The culture converts the milk’s lactose into lactic acid, while the rennet acts as a coagulate to set the cheese. The curds (solidified milk protein) separate from the whey during this process. To strain the rest of the whey from the curds, the cheesemaker scoops out the curds and further strains them through a cheesecloth. The curds are then ready to be made into cheese, while the whey is ready to be used however you’d like.

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7 Ways to Use Whey

While many home cooks throw out liquid whey as an unusable byproduct of cheese, whey actually has many uses in the kitchen and beyond.

Both sweet and acid whey can be used for all kinds of things. When cooking with them, keep in mind the flavors you’re working with—if you’re making something sweet, then sweet whey will be the best, and if you’re making something savory, acid whey will work great. Consider using whey in the kitchen for:

  1. Ricotta cheese. Ricotta (an Italian word that means “recooked”) is a cheese made from the whey left over from making a different cheese. Ricotta is easy to make at home and is a staple in many Italian pasta dishes, including lasagna.
  2. Baked goods. Anywhere that a baking recipe calls for skim milk or water, liquid whey can be used instead. Try it in bread loaves, homemade crackers, waffles, pizza dough, rolls, and more.
  3. Soup stock. Whey has a deep, slightly sour taste that will add a unique flavor to soup, similar to the way a soup stock will.
  4. Dressings and marinades. Whey’s unique flavor will add some interest to any dressings or marinades for meat or vegetables.
  5. Cocktails and smoothies. Whey is a popular ingredient in most dairy-based cocktails. It’s also a great addition as the liquid ingredient in shakes and smoothies.
  6. Whey butter. While most of the cream is strained out of whey during cheesemaking, there is still enough cream present to make a particular type of butter called whey butter. Let it sit until the cream rises to the top, then skim it off to churn.
  7. Pasta or rice. If your kitchen is still full of whey from tons of cheesemaking, use whey in place of water when boiling pasta or rice—it will give it some extra flavor and use up your excess whey!


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Is Whey Dairy?

While whey has been mostly strained of cream, it still contains lactose, which means that those with allergies to dairy products should avoid drinking or cooking with whey.

What Is Powdered Whey Protein?

While whey in its liquid form has a number of uses, it is also powdered commercially and sold as a high-protein dietary supplement called whey protein or whey protein powder. Whey protein powder is full of quality protein alpha-lactalbumin, protein building blocks like branched-chain amino acids (notably leucine and cysteine), and other essential amino acids.

Whey protein is popular among bodybuilders and athletes, who use whey (often mixed into smoothies or other drinks) to maximize their daily protein intake. Enough protein paired with resistance training can help athletes improve their athletic performance by increasing muscle strength, can help them change their body composition by encouraging muscle protein synthesis and building muscle (especially lean muscle), and can help encourage satiety (the feeling of being full).

What Is the Difference Between Whey Concentrate, Whey Isolate, and Why Hydrolysate?

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There are three types of whey protein supplements:

  • Concentrate. Whey protein concentrate ranges between 30 to 75 percent protein and contains more lactose, fat, and nutrients.
  • Isolate. Whey protein isolate is usually around 90 percent protein and contains less lactose, less fat, fewer carbs, and fewer nutrients.
  • Hydrolysate. Whey protein hydrolysate is a “pre-digested” protein, meaning it has gone through part of the hydrolysis process and will be much faster absorbed than whey concentrate or whey isolate. It ranges in protein percentage and contains almost no lactose, and its reduced allergen potential makes it popular for infant formula and for those with lactose intolerance.

Whey protein is just one of many types of protein powders. Other proteins include soy protein, casein protein, and creatine.

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