Whey Cheese Production & Whey Valorisation

What is a whey cheese?

A whey cheese is made from whey, the liquid by-product of normal cheesemaking, rather than from whole milk. Whey retains roughly 50% of the solids of the original milk, including most of the lactose and the whey proteins (the “albumin” fraction). There are two fundamentally different products:

• Albumin cheeses — made by coagulating the whey proteins with heat (sometimes with added acid), e.g. Ricotta, Mizithra, Manouri, Anari.
• Brown whey cheeses — made by evaporating whey until the lactose caramelises, e.g. Brunost and the other Nordic mysost cheeses.

The whey-protein coagulation process (albumin cheeses)

The whey proteins — mainly beta-lactoglobulin and alpha-lactalbumin, with serum albumin and immunoglobulins — are heat-labile, unlike casein. Heating whey (often with a little added milk or cream) to about 88–92°C denatures and coagulates them; added or natural acidity assists. The coagulated protein floats to the surface, where it is skimmed or ladled off and drained. No starter culture is used after the heat step.

1. Collect fresh whey from cheesemaking (optionally add milk and/or cream for richness and yield).
2. Adjust acidity if required (acid whey, citric or lactic acid).
3. Heat to about 88–92°C with minimal agitation.
4. The whey proteins denature, coagulate and float to the surface.
5. Skim or ladle the soft curd off the surface.
6. Drain in baskets or cloth; then cool and pack (fresh) or salt, press and dry (ripened).

Ricotta and the albumin whey cheeses

Ricotta — the name means “recooked” — is the best-known example. Traditionally Italian and made from sheep-cheese whey (often with added milk), it was described by the Roman writer Columella around 50 AD. Fresh ricotta is soft, high-moisture and unpressed. Ripened and dried versions such as Ricotta Salata and Mizithra are salted, pressed and dried for grating, with moisture falling from around 70% to about 40%. Related albumin cheeses include Anthotyros and Manouri (Greece, richer — whey plus milk or cream, a PDO), Anari (Cyprus, made from the whey left over from Halloumi), Requeijão (Portugal), Requesón (Spain and Mexico) and Brocciu (Corsica). Modern plants use continuous ricotta lines and ultrafiltration to lift and stabilise yield (Maubois & Kosikowski, 1978).

Brunost — the Nordic brown whey cheeses

Brunost (“brown cheese”) is made by boiling and simmering whey — usually with added milk and cream — for several hours until the water evaporates and the lactose caramelises through the Maillard reaction, giving the characteristic brown colour and sweet, fudge-like flavour. Variants include Gudbrandsdalsost (whey plus cow's milk and cream), Gjetost (made with goat's milk) and Fløtemysost (cow's milk and cream). The same idea appears across the Nordic countries as mysost, mesost and myseost, and in German-speaking areas as Braunkäse. No protein is coagulated here — the product is essentially concentrated, caramelised whey solids.

Whey valorisation — turning a cost into a product

The scale is the point. About 9 kg of whey is produced per kg of cheese; whey is 85–95% of the milk volume and retains roughly 55% of the milk nutrients, about 20% of the protein and most of the lactose. A typical sweet whey is around water 93–94%, lactose 4.5–6.0%, protein 0.6–1.1%, minerals 0.8–1.0% and fat 0.06–0.5%. Lactose makes up 70–75% of the solids and is responsible for roughly 90% of the organic load: whey has a BOD of about 27–60 g/L and a COD of about 50–102 g/L — on the order of 100 times stronger than domestic sewage — so untreated disposal to water or land is prohibited under EU and national law.

Whey cheese recovers the heat-coagulable proteins, but it leaves behind “second cheese whey” that still carries about half of the original whey's dry matter, mostly lactose, and itself needs valorising. The higher-value route is membrane processing — ultrafiltration, nanofiltration and reverse osmosis — to recover whey proteins and lactose as WPC, WPI and lactose powders.

Composition & comparison

Plant & equipment

A fresh-albumin (ricotta) line is built around steam-jacketed ricotta vats or kettles, or continuous ricotta extractors, with acid dosing, gentle heating to around 88–92°C, surface skimming or automated separation, and draining baskets; ultrafiltration is used where yield and consistency matter. A brown-cheese line needs scraped-surface evaporators or boiling pans to concentrate the whey and develop the caramel. Whichever route, the second cheese whey still has to be managed — usually by membranes — rather than discharged.

Frequently Asked Questions

What is whey cheese?

A cheese made from whey, the by-product of normal cheesemaking, rather than from whole milk. Whey retains about half the milk solids, including most of the lactose and the whey proteins. There are two kinds: albumin cheeses such as ricotta, made by heat-coagulating the whey proteins, and brown cheeses such as Brunost, made by evaporating whey until the lactose caramelises.

How is ricotta made, and is it really cheese?

Ricotta is made by heating whey (often with a little added milk or cream) to about 88 to 92C, sometimes with added acid. The whey proteins denature and float to the surface as soft curds, which are skimmed off and drained. It is a whey cheese rather than a rennet-curd cheese, but it is genuinely a cheese - the name means recooked.

What is the difference between ricotta and brunost?

Ricotta is made by coagulating whey proteins with heat, giving a soft white fresh cheese. Brunost (Nordic brown cheese) is made by simmering whey until the water evaporates and the lactose caramelises, giving a brown, sweet, fudge-like product. One coagulates protein; the other concentrates and caramelises whey solids.

How much whey does cheesemaking produce?

About 9 kg of whey for every 1 kg of cheese. Whey is 85 to 95% of the milk volume and retains roughly 55% of the milk nutrients, about 20% of the protein and most of the lactose.

Why can't whey just be poured away?

Because its organic load is very high - a BOD of roughly 27 to 60 g/L and a COD of about 50 to 102 g/L, on the order of 100 times stronger than domestic sewage, driven mainly by lactose. Untreated disposal to water or land is prohibited under EU and national law, so whey must be processed or valorised.

Is ricotta made from whey or milk?

Traditionally from whey - it is the classic way of recovering the whey proteins left after cheesemaking. In practice many ricottas have some whole milk or cream added to improve yield, richness and texture, but the base is whey.

Further reading: John Watson publishes articles on dairy industry topics on LinkedIn. Browse all articles by John Watson on LinkedIn →