What is cow’s milk made of?

In this brief article, we will provide you with the answer to the question: “What is cow’s milk made of?”, with a deep discussion about each component of milk.

What is cow’s milk made of?

The primary components in cow’s milk (Ash) are water, fat, protein, carbohydrate (lactose), and minerals.. However, there are other micronutrients that are extremely necessary, such as vitamins, vital amino acids, and trace minerals.  Indeed, over 250 chemical components have been discovered in milk. 


Lactose is the primary carbohydrate in milk. It is generated by the mammary gland’s epithelial cells and is the primary source of energy for babies. Other carbohydrates, such as glucose and galactose, can be present in milk in modest amounts in addition to lactose.

Lactose is broken down in the food by the enzyme lactase into its component glucose and galactose subunits. The glucose and galactose can then be absorbed and used by the body after passing through the digestive tract. 

Lactose intolerance occurs when an individual lacks lactase, which prevents lactose from being metabolized. Lactose that has not been digested cannot be absorbed from the digestive tract and hence accumulates, causing intestinal pain.

Lactose accounts for roughly 52 percent of the total solids in skim milk and 70 percent of the solids in whey. It regulates milk production by extracting water from the circulation to equalize osmotic pressure in the mammary gland. 

The amount of water in milk, and hence the amount of milk produced by the cow, is determined by the amount of lactose released in the mammary gland. Lactose content in milk is roughly 5%. (4.7 to 5.2 percent ). It is one of the most stable components of milk, meaning it is less susceptible to fluctuations.


Proteins account for approximately 3% and 4% of the solids contained in milk. The quantity of protein varies with breed and is related to the amount of fat in the milk, among other things. This indicates that the larger the proportion of fat in milk, the higher the proportion of protein.

Milk contains numerous different forms of protein. The most important is casein, which has a high nutritious quality and is used in the production of cheese. 

Casein is generated by mammary gland secretory cells and is structured in the form of micelles, which are groupings of multiple casein molecules with calcium, phosphorus, and other ions. This type contains around 95% of the total casein in milk. 

Casein micelles and fat globules are responsible for the majority of the qualities associated with the consistency and color of dairy products.

Casein is not easily affected by heat, and it remains rather stable when milk is pasteurized. When milk acidity changes, the micelle structure is broken, causing casein to precipitate and form clots. Fat and casein are critical ingredients in the production of many dairy products, as they have the largest concentration of solid constituents in cheese.


Milk fat is found in the aqueous phase in the form of tiny globules. Each globule is surrounded by a layer of a phospholipid, which is a fat component. This layer produces a barrier that prevents all of the globules from combining. The milk fat is maintained suspended in this manner.

The majority of milk fat is composed of triglycerides, which are composed of fatty acids connected to glycerol. Milk fat is found as tiny globules floating in the water. Milk’s fat fraction transports fat-soluble vitamins (A, D, E, K), cholesterol, and other fat-soluble compounds such as carotenoids (provitamin A), which give milk its creamy yellow color.

The fat concentration in milk normally ranges between 3.5 and 5.3 percent, depending on breed, stage of lactation, and the food of the animals.

Vitamins and mineral salts

Milk is a great source of the majority of the minerals required for young people’s growth. Calcium and phosphorus are readily accessible in milk, thanks in part to their association with casein. 

As a result, milk is the greatest source of calcium for both the growth of a young person’s skeleton and the preservation of the integrity of an adult’s bones. The iron concentration is quite low.

Milk contains a variety of vitamins, some of which are connected with the fat (A, D, E, and K), while others are related to the watery portion. However, with the exception of vitamin B2 (riboflavin), the others are found in small amounts. B vitamins are produced in the compound stomach (rumen) of animals.

Milk is an important source of vitamin C (ascorbic acid), but this is rapidly oxidized in the presence of copper to a biologically inactive product.


In this brief article, we provided you with the answer to the question: “What is cow’s milk made of?”, with a deep discussion about each component of milk.


“Agência de Informação Embrapa Composição”. Acessado 2 de fevereiro de 2022. https://www.agencia.cnptia.embrapa.br/Agencia8/AG01/arvore/AG01_128_21720039243.html.

“Dairy Product | Definition, Types, Nutritional Content, & Production | Britannica”. Acessado 2 de fevereiro de 2022. https://www.britannica.com/topic/dairy-product.

Hi, I am Charlotte, I love cooking and in my previous life, I was a chef. I bring some of my experience to the recipes on this hub and answer your food questions.