Whey

Whey is the liquid remaining after milk has been curdled and strained. It is a by-product of the manufacture of cheese or casein and has several commercial uses. Sweet whey is manufactured during the making of rennet types of hard cheese like cheddar or Swiss cheese. Acid whey (also known as "sour whey") is a by-product produced during the making of acid types of dairy products such as cottage cheese or strained yogurt.

Production

To produce cheese, rennet or an edible acid is added to heated milk. This makes the milk coagulate or curdle, separating the milk solids (curds) from the liquid whey. Sweet whey is the byproduct of rennet-coagulated cheese and acid whey (also called sour whey) is the byproduct of acid-coagulated cheese. Sweet whey has a pH greater than or equal to 5.6, acid whey has a pH less than or equal to 5.1.

Uses

Whey is used to produce whey cheeses such as ricotta, whey butter, so-called brown cheeses such as Brunost (technically not cheeses at all), and many other products for human consumption. The fat content of whey is low; for example 1,000kg of whey are required to make typically 1kg of whey butter. It is also an additive in many processed foods, including breads, crackers, and commercial pastry, and in animal feed. Whey proteins consist primarily of α-lactalbumin and β-lactoglobulin. Depending on the method of manufacture, whey may also contain glycomacropeptides (GMP).