What Chemicals Can Be Found in Milk?

Lucy Bell-Young

by Lucy Bell-Young

21st July 2021

Blog

There are a lot more chemicals in milk than you might expect. As a naturally-occuring baby and infant food for mammals, it’s rich in protein, fats, lactose, vitamins, and minerals that are essential for growth and development. Even in adulthood and old age, milk is still an important substance in our diet.

A Complete List of Chemicals in Milk

The exact composition of chemicals in milk varies, depending on the natural source or artificial formulation. For example, some commercially available infant formula milk brands are fortified with vitamins and minerals that aren’t normally available in natural cow’s milk.

While most of the chemicals in milk have nutritional value, some don’t offer any form of nutrition, such as in the case of commercially available milk brands, which include artificial additives like food colouring, preservatives, and synthetic sweeteners in their products.

However, the majority of naturally occurring chemicals found in cow’s milk are the following:

  • Moisture/water (87%): The main constituent of milk is water, which serves as the solvent and colloidal medium for all other chemicals, including vitamins.
  • Fat (3.9%): Otherwise known as lipids, the different types of fats in milk include triacylglycerides, diacylglycerides, saturated and polyunsaturated fatty acids, and phospholipids. Also present are fat-soluble vitamins, vitamin A, vitamin D, vitamin E, and vitamin K (phytomenadione). Of the twelve major types of fatty acids found in milk, only three (lauric, myristic, and palmitic) are associated with increasing the cholesterol levels in blood plasma.
  • Proteins (3.4%): Casein and whey proteins form the majority of proteins found in cow’s milk. Casein comprises around 80% of the protein in milk, while approximately 20% are whey proteins (see more on casein below). Casein is primarily phosphate-conjugated and is mainly composed of calcium phosphate, known as micelle complexes. Other types of proteins in milk are various kinds of enzymes in trace amounts.
  • Lactose (4.8%): Lactose is a type of sugar classified as a disaccharide. It’s composed of two sugar subunits: galactose and glucose. The chemical formula for lactose is C12H22O11. Some people are incapable of digesting lactose. These people typically experience upset stomachs when they drink milk or eat dairy products like cheese. This intolerance is actually an evolutionary throwback: lactose intolerant adults don’t have the mutation that allows for the production of an enzyme called lactase, which digests lactose.
  • Minerals (0.8%): The bones, teeth, blood, nerves, and muscles all need one or more types of minerals to maintain their structure and function properly. For example, calcium is necessary for bone growth and for heart contraction. Milk has traces of various minerals in edible, digestible forms. The major minerals found in milk are calcium, sodium, potassium, iron, magnesium, and phosphorus. Milk also contains trace amounts of other minerals such as iodine, fluorine, chlorine, zinc, cobalt, and selenium.

Most types of milk on the market, whether powdered or fresh, are derived from cow’s milk. These days, there are also many plant-based and non-dairy alternatives, like soya and almond milk. Technically, these aren’t classified as milk, but they contain similar nutrients as real milk. 

Other less popular types of milk (especially in the UK) are water buffalo’s milk, goat’s milk, sheep’s milk, and camel’s milk. Dairy products such as cheese, butter, ice cream, and yogurt can also be derived from these various types of milk.

Casein written on chalkboard with a cup of milk and a scoop of milk powder on wood background
Casein forms the majority of proteins found in cow’s milk

What Chemical Preservatives Are Used in Milk?

Fresh milk undergoes a pasteurisation process. Even still, the lifespan or storage life of fresh milk is very short. Even under ideal refrigeration conditions, pasteurised milk only lasts between two to five days. 

To remedy the relatively short shelf life of milk, large food processing and manufacturing companies make powdered milk and modified liquid milk, like condensed milk. These products have preservatives that prevent spoilage even long after they’re opened. Powdered milk products, for example, don’t need refrigeration. You only need to make sure the container is airtight because prolonged exposure to open air can ruin the product.

So, while fresh milk typically doesn’t have any artificial preservatives, other forms of milk, like powdered milk, evaporated milk, and condensed milk, contain chemical preservatives to make them last. The major types of preservatives used are:

  • Sodium benzoate (C7H5NaO2)
  • Potassium sorbate (C6H7KO2)
  • Natamycin (C33H47NO13)
  • Calcium propionate (C6H10CaO4)
  • Sorbic acid (C6H8O2)
  • Ascorbic acid (C6H8O6)
  • Sucrose (C12H22O11)

Most of these preservatives are either antifungal or antibacterial. Some are even antioxidants, like ascorbic acid, otherwise known as vitamin C. This is usually added as a supplement, but it also prevents the oxidation of milk components. Some preservatives, like sucrose, also function as adulterants or extenders. 

3d illustration of sodium benzoate
Sodium benzoate is one of the major types of preservatives used in milk

Are Chemicals in Milk Dangerous?

While milk can be dangerous to those who are lactose intolerant, the chemicals in milk are perfectly safe for most people. There is nothing toxic or dangerous about the chemicals in milk unless the milk has spoiled, which could cause food poisoning.

While different types of processed milk contain preservatives and adulterants, these are well-regulated by the Food Standards Agency (FSA) in the UK. 

Spoiled milk and lactose intolerance aside, the only real danger of drinking milk or eating dairy products is milk allergy. Put simply, some people are just allergic to milk. These people may experience vomiting, wheezing, hives, digestive problems, and possible anaphylaxis, which can be life threatening.

For people who aren’t lactose intolerant and don’t have any allergies, drinking milk in moderation is safe and healthy.

What is Casein?

Casein is the main type of protein found in mammalian milk. In cow’s milk, for instance, casein forms 80% of all the protein it contains. The remaining 20% is whey protein. However, casein only forms between 20% and 60% of the proteins found in human milk. Sodium caseinate is the most prevalent form of casein. Casein is a good source of amino acids, carbohydrates, and two essential nutritional elements: calcium and phosphorus.

What’s the Chemical Formula for Casein in Milk?

In milk, casein takes the form of colloidal particles known as casein micelles. These are polydisperse (or of various sizes), large, and roughly spherical in shape – between approximately 50 and 600 nanometers in diameter. 

Casein is a relatively simple protein molecule with a high number of proline amino acids. This hinders the formation of secondary structural folds or motifs. The molecule also has no disulfide bridges, which makes it difficult to form tertiary structures.

The chemical formula for casein can be written as C81H125N22O39P. Meanwhile, the molecular structure can be illustrated as:

Disclaimer

All content published on the ReAgent.ie blog is for information only. The blog, its authors, and affiliates cannot be held responsible for any accident, injury or damage caused in part or directly from using the information provided. Additionally, we do not recommend using any chemical without reading the Material Safety Data Sheet (MSDS), which can be obtained from the manufacturer. You should also follow any safety advice and precautions listed on the product label. If you have health and safety related questions, visit HSE.gov.uk.

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