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Discover the proteins contained in milk and their characteristics

Vaso de leche sobre mesa de madera

Milk is an essential food in many people’s diets thanks to its high quality protein content. Milk proteins contain essential amino acids that our body cannot produce, providing energy, muscle maintenance and immune support.

What are the proteins in milk?

The proteins present in milk are divided into two main groups: caseins and whey proteins.

Caseins represent approximately 80 % of the total protein content of milk. They are organised in aggregates called caseinates and are responsible for the structure of the cheese when the milk curdles. Biologically, they are characterised by their slow release of amino acids, which makes them ideal for maintaining sustained amino acid levels in the blood.

Whey proteins account for about 20 % and are more soluble: they include alpha-lactalbumin, beta-lactoglobulin, immunoglobulins and bovine serum albumin. They are rapidly digested, allowing rapid absorption of amino acids, which is beneficial for muscle recovery after exercise.

Functions and features

Dairy proteins perform many essential functions:

  • Complete nutrition: they provide all the essential amino acids.
  • Muscle support and recovery: especially those in serum, because of their rapid effect.
  • Boosting the immune system: immunoglobulins and lactoferrin improve the immune system.
  • Tissue formation: case of repair and cell growth.
  • Texture and food processing: casein is key in cheese and yoghurt production.
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Types of whey proteins

Within the serum, several fractions stand out:

  • Alpha-lactoalbumin: rich in tryptophan, helps serotonin synthesis.
  • Beta-lactoglobulin: provides a quick source of amino acids.
  • Immunoglobulins: strengthen the defence response.
  • Lactoferrin: protects against infections and has an anti-inflammatory function.

Comparison with other proteins

Compared to sources such as pulses or meat, milk stands out for its higher biological value (3-5% higher). In addition, the combination of caseins and whey allows for a mixed nutritional effect: sustained release of amino acids and rapid replenishment.

Health impact

  • Bone and tooth mass: proteins facilitate calcium absorption and collagen formation.
  • Weight control: due to its satiating capacity and high thermic effect.
  • Digestive well-being: whey can support a balanced microbiota.

Thanks to their nutritional properties, milk proteins are also used in processed products. A widely used format due to its durability and versatility is milk powder, which maintains the protein content and facilitates its use in multiple food applications.

Frequently asked questions on milk proteins

One glass provides 8-9 g of protein, distributed mainly between caseins (≈6-7 g) and whey (≈2-3 g).

No. It may vary according to animal species, cow feed or milk processing (whole, semi-skimmed…).

People with milk protein allergy and lactose intolerant people, although there are already some lactose-free protein references on the market, which can be safely consumed by the latter.

They may be useful for athletes or people with high protein requirements; it is always advisable to consult a professional.

Yes, the protein content is retained, although much of the fat is removed.