🧪 Whey protein

Whey protein is a group of milk proteins that stay in solution when casein is precipitated from the milk, for example during cheese making. In cow's milk they make up about 19% of all the protein, or 6.4 g per kilogram. The main one in cow's milk is beta-lactoglobulin.

It is a mixture of several proteins. According to Tetra Pak, a kilogram of milk holds 3.2 g of beta-lactoglobulin (about half of the whey proteins), 1.2 g of alpha-lactalbumin, 0.4 g of serum albumin and 0.8 g of immunoglobulins. Heating changes them: beta-lactoglobulin begins to denature above 60 °C.

Whey is the liquid left after cheese. It makes up 80–90% of the milk's volume and holds about half of its nutrients, with about 0.6% protein. It used to be treated as waste, but today concentrates (20 to 85% protein in dry matter) and isolates (over 90%) are obtained from it. They go into baby and sports nutrition, ice cream and other products.

What can be said about benefits. The EU allows claims about an increase and maintenance of muscle mass and normal bones for protein in general, but only for foods where protein provides at least 12% of the energy. For whey protein on its own, EFSA in 2010 found no established link with satiety or a normal body weight. Milk and its products, whey products included, count as allergens in the EU.

Whey protein or casein, or plain milk protein? Both come from the same milk. Casein is about 78% of the protein and is the part that curdles when cheese is made, while whey proteins, about 19%, stay in the liquid whey. That whey is the leftover of cheese making, with about 0.6% protein, and was once treated as waste. A powder sold as whey protein is therefore a processed product, and its main protein in cow's milk is beta-lactoglobulin. Heat changes it: it begins to denature above 60 °C.

On the shelf, look for the type named in the ingredients or product name: whey protein concentrate or whey protein isolate, since the two differ in protein content. The protein percentage is shown in the nutrition table, which is the number worth comparing. Milk is listed as an allergen on the pack. You will mostly find such powders in sports nutrition shops, pharmacies, supermarkets and online, while baby formula and ice cream may contain whey ingredients too.

Why it matters to you. A "whey protein" powder is a product of milk processing, not a remedy with a proven effect on weight. On the label, check the protein content and the type: concentrate or isolate. With a milk allergy, such products are not suitable.