🧀 Whey

Whey is the liquid left over after milk curdles during cheese or curd making. Whey is the liquid left after milk is curdled and the curd separated in making cheese, curd cheese or casein. Most of the milk’s water, lactose and mineral salts pass into it, along with the whey proteins (beta-lactoglobulin, alpha-lactalbumin and others) that do not become part of the casein curd. Making 1 kg of cheese produces roughly 8–9 litres of whey.

There is sweet whey (from rennet cheeses) and acid whey (from curd cheese, Greek yogurt and other acid-set products). Whey is used to make whey cheeses (ricotta, Norwegian brunost), drinks, whey powder, lactose, and whey protein concentrates and isolates for sports and infant nutrition.

For a long time whey was considered waste, and dumping it into rivers and lakes polluted the environment; today processing it is an important part of the dairy industry. Whey differs from buttermilk in origin: buttermilk is left after churning butter, whey after curdling milk.