Natural form

Fresh liquid whey separating from white cheese curds in a colander.

Shows whey in its most recognizable form — the pale yellow liquid draining away from solid curds — teaching readers exactly what it is and where it comes from.

Dairy & Eggs

Whey

Liquid left after curdling milk, used as a starter, in baking, brining, and protein powders.

Whey is the watery liquid that separates from curds during cheesemaking, carrying milk sugars, some protein, and tang. Cooks use fresh whey as a fermentation starter, a brine for proteins, a liquid in breads and pancakes, or to make ricotta, while dried whey protein isolate is a concentrated powder for shakes and baking. It adds a subtle acidity and tenderizing effect.

Whey is the liquid remaining after milk has been curdled and strained during cheese-making, separating the coagulated curds from their liquid medium. This ancient byproduct has been documented in Greek and Roman culinary traditions and gave rise to distinctive cheeses like ricotta and gjetost, which were developed specifically to make use of the whey left from other cheese productions. The yield is substantial—approximately 80–90% of the original milk volume separates as whey during cheese-making, making it one of the most abundant dairy byproducts. In modern cooking, whey occupies a peculiar position: abundant at artisanal cheese operations, where it is often discarded in enormous quantities, yet rare in everyday home kitchens where its versatility remains largely untapped.

There are two primary types defined by their coagulation method. Sweet whey, the byproduct of rennet-coagulated hard and semi-hard cheeses like cheddar and Swiss, has a pH between 5.9 and 6.6 with a mildly sweet flavor. Acid whey, from acid-coagulated fresh cheeses such as cottage cheese and cream cheese, has a lower pH of 4.6 to 5.1 and a noticeably sharper, tangier character. Both contain lactose at approximately 4.8%, whey protein with a complete amino acid profile, B vitamins, calcium, potassium, and phosphorus. The liquid form contains roughly 1% protein, while processed concentrates range from 35% to over 90% protein by weight. Fresh whey keeps refrigerated for up to five days or frozen for three months; dried whey powder remains stable for twelve months or more in cool, dry storage.

The value of whey in cooking extends far beyond its modest flavor—it functions as a neutral cooking liquid, fermentation medium, brining agent, and nutritional enhancer. The fermentation properties make it particularly valuable for sourdough bakers, as natural lactose and proteins feed beneficial bacteria and wild yeast. In brining applications, whey proteins denature at the meat surface similarly to salt brines, improving moisture retention and browning capacity. For home cooks, cottage cheese drainage provides the most accessible source of acid whey for experimentation.

Measured in: ml
Storage: Fridge

Allergens

Dairy

Types & varieties

Sweet Whey

Byproduct of rennet-coagulated hard and semi-hard cheeses (cheddar, gouda, Swiss); pH 5.9–6.6; mildly sweet flavor; most common commercial type

Acid Whey

Byproduct of acid-coagulated fresh cheeses (cottage cheese, farmer's cheese, cream cheese); pH 4.6–5.1; sharper, tangier flavor; contains more lactic acid and minerals

Milk Permeate

Ultrafiltered whey with reduced protein content; byproduct of dairy processing; used as an additive in processed foods and animal feed

Demineralized Whey

Whey with 25–90% of minerals removed through ion exchange; used in infant formulas and specialty food applications

Whey Protein Concentrate

Liquid whey concentrated to 35–80% protein; common in protein powders, sports nutrition, and food formulations

Whey Protein Isolate

Further processed to 90%+ protein content with minimal lactose; most expensive form; used in medical nutrition and high-protein foods

The Brining Advantage

Whey performs a dual function in brining poultry and pork. The proteins denature at the meat surface, creating a barrier that helps retain moisture during cooking—similar to traditional salt brine effects but with added nutritional benefit. Simultaneously, the mild acidity slightly tenderizes surface proteins, improving browning capacity. For best results, use fresh whey within 48 hours and combine with salt and aromatics for a more complex brine.

Replace up to half the liquid in a standard brine with whey
Add 1 tablespoon salt per cup of whey for poultry
Include garlic, peppercorns, and fresh herbs for flavor depth
Brine poultry for 4–12 hours; pork for 8–24 hours depending on cut thickness

Sourdough and Fermentation

Whey provides readily fermentable sugars for wild yeast and beneficial bacteria in sourdough starters and vegetable ferments. The lactose in whey is particularly valuable because it ferments differently than glucose, producing unique organic acids that enhance flavor complexity. For sourdough applications, replace up to 25% of the water with whey for a softer crumb and improved fermentation activity. The slight acidity also helps activate natural yeast in whole wheat and hearty grain breads, improving gluten development and rise.

Add whey to unfed sourdough starter to boost activity
Replace water with whey 1:1 in levain builds
Use whey in place of water for vegetable lacto-ferments
The acidity helps develop flavor in whole-grain and seeded breads

Common uses

Starter culture for fermented foods including sourdough, vegetables, and traditional beveragesProtein supplement in shakes, smoothies, and baking recipesBrining liquid for poultry and pork to improve moisture retention and browningCooking liquid for bread and sourdough for a tender crumb and enhanced fermentation activityPan deglazing and sauce base in place of wine or stockRicotta and whey cheese productionTraditional whey beverages in Scandinavian and Baltic culinary traditionsThickening agent in soups, stews, and cream-based saucesMarinade component for tenderizing meats before cookingIce cream and frozen dessert base for improved texture and reduced icinessPasta water substitute in grain bowls and risottos for added nutritionBase for Polish żur and Scandinavian whey soups

Tips & pitfalls

Do not discard whey from cheese-making or cottage cheese drainage—it can replace water in virtually any recipe with minimal flavor impact and added nutrition
Use fresh whey within 24–48 hours for optimal quality in drinking, fermentation, and brining applications
When brining, whey proteins denature at the meat surface, improving moisture retention and browning capacity
For sourdough starters, whey provides readily available sugars for wild yeast and bacteria—stimulates activity faster than water alone
Freeze whey in ice cube trays for convenient portioning when adding to smoothies, batters, or soups
Avoid boiling or extended high-heat cooking with whey, as proteins may denature and create off-flavors and a scalded taste
Acid whey curdles when heated to high temperatures—reserve it for cold applications, gentle warming, or use sweet whey for cooked preparations
Strain fresh whey through cheesecloth or fine mesh to remove any remaining curds before using in beverages or sauces
Avoid whey for individuals with lactose intolerance or milk protein allergies—the lactose content (~4.8%) remains significant even in sweet whey, and all whey forms contain milk proteins

Nutrition

24kcal

Energy

100 kJ · per 100 g

Where the calories come from

Protein 12%Carbs 84%Fat 3%

Protein

0.8g

2% DV

Carbs

5.1g

2% DV

Fat

0.1g

0% DV

Fiber

0% DV

Sugars

5.1g

of which

Sodium

48mg

2% DV

Notable micronutrients

Riboflavin (B2)11% DV

Vitamin B128% DV

Calcium8% DV

Phosphorus6% DV

Thiamin (B1)4% DV

Zinc4% DV

Source · USDA FoodData Central · Whey, acid, fluid

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Good to know

Primary Types: Sweet whey (pH 5.9–6.6, rennet-coagulated) and acid whey (pH 4.6–5.1, acid-coagulated)
Key Nutrients: Lactose, complete-profile whey protein, B vitamins, calcium, potassium, phosphorus
Protein Content: ~1% in fresh liquid whey; 35–80% in concentrates; 90%+ in isolates
Yield: ~80–90% of milk volume yields as whey during cheese-making
Lactose Content: ~4.8% in fresh whey; significantly reduced in isolates
Flavor Profile: Mildly sweet and slightly tangy; acid whey is noticeably sharper
Shelf Life: 5 days refrigerated; 3 months frozen; 12+ months dried
Origin: Ancient byproduct of cheese-making, documented in Greek and Roman culinary traditions

Substitutes

Buttermilk — Similar tangy dairy liquid; best for baking and brining; differs in protein content but acceptable in most applications
Milk — Substitute for liquid whey in soups and sauces; lacks the slight tartness and may affect protein-dependent applications
Yogurt Whey — Liquid strained from yogurt; similar acidity and culture profile; excellent for fermentation and dressing applications
Water with Lemon Juice — Approximation of acid whey acidity; use 1 tablespoon lemon juice per cup of water for similar pH in brining or baking
Chicken or Vegetable Stock — For savory applications calling for liquid; will alter flavor significantly but provides similar cooking medium
Aquafaba — Chickpea cooking liquid; provides some protein and works as egg white substitute; different flavor but functional equivalence in some baking applications

Pairs with

Grains (rice, farro, quinoa)Sourdough and whole wheat floursCitrus (lemon, orange)Fresh herbs (parsley, dill, chives)Honey and maple syrupGarlic and shallotsRoot vegetables (potatoes, carrots, parsnips)Fish and shellfish

Also called

Whey (Starter) · Whey Protein Isolate · Milk Whey