What Milk is Made Of & How It’s Processed
Milk is one of those few essential foods that we are practically unable to live without, so it is only natural to wonder what milk is made of.
It’s so important to us, that we would run to the supermarket at night to grab a bottle, lest we run out of the white stuff before breakfast time. We pour it onto our breakfast cereal and into our drinks, and use it in all sorts of cookery. Not to mention, milk is the basis for every single other dairy product we know and love including butter, cream, cheese, yogurt and ice cream.
Milk is a must-have food for many people, yet many of us don’t really know what milk is made of and how it’s processed.
In this article I’ll share with you:
- Introduction: What Milk is Made Of
- Ingredients: What is in Milk
- Processing: How Milk is made (infographic)
- History of Milk
Introduction: What Milk is Made Of
What milk is made of…
Let’s jump straight to the point. Milk is a white bodily fluid produced by the mammary glands of female mammals. The generic term ‘milk’ usually refers to cow’s milk, although all other mammals including humans also produce milk. Goat’s and sheep’s milk are common alternatives to cow’s milk.
Plain milk is rich in protein and calcium, whereas flavoured milk often has added sugar, flavours and colour. Milk is often consumed plain, or made into chocolate milk, iced coffee and other flavoured milk. Milk comes in whole (3–5% fat), low-fat (1–2% fat) and skim (<0.5% fat) varieties. Vitamins A and D are often added to replace any that were lost during processing.
Lactose-free milk and how lactose is removed from milk
Lactose-free milk is also available to people who are sensitive to the lactose sugar that occurs naturally in milk. Lactose-free milk is made by exposing milk to the enzyme lactase, which breaks lactose sugar in milk down into glucose and galactose.
Ingredients: What is in Milk
As you might have guessed, plain milk contains only one ingredient: milk.
Whole milk is what percent?
Whole milk is 3–5% fat. Low-fat milk is 1–2% fat, and skim milk contains <0.5% fat.
Flavoured milk, such as chocolate milk and iced coffee, contain many other added ingredients for flavour and texture. Common ingredients in flavoured milks include any or all of the following:
- Milk
- Vitamins
- Sugar
- Flavours
- Colours
- Caffeine
- Emulsifiers, Stabilisers
- Thickeners
Processing: How Milk is Made
Even though milk is an essential item in many of our diets, it is surprising how many people especially children, simply do not know what milk is made of and how it is processed. While writing my non-fiction food comic book How Food is Made: An illustrated guide to how everyday food is produced (more about the book here) I researched a ton of food science and food industry books, magazines and journals to get the real answer to the query ‘What milk is made of and how it is processed’, which I give to you now.
As explained earlier, milk is a bodily fluid produced by cows. To understand what milk is made of and how it is processed, we first need to understand the cow’s reproductive system a little. For a cow to produce milk, the cow must first become pregnant and give birth to a calf. The process of giving birth triggers the cow to start making milk to feed her calf. In most cases, the calf is taken away from the cow, while the cow continues to produce milk which is pumped out and processed ready for sale.
The following infographic (and the text in this post) is an extract from my book How Food is Made and outlines how milk is processed, from cow to carton.
What is milk pasteurization and homogenization?
What is milk pasteurization?
Milk pasteurization is the practice of heating milk to a certain temperature to kill harmful bacteria that can cause illness. It makes milk safer to drink.
Raw milk is the milk as it has come straight from the cow, with no processing carried out on it. Raw, unpasteurised milk is illegal to sell in some regions due to health risks. Most milk for sale is pasteurized and homogenized.
Milk pasteurization involves heating the milk to a certain temperature, to kill off pathogens and harmful bacteria. The purpose of milk pasteurization is to make the milk safer to drink, so that people do not get sick from it. Pasteurization is carried out on a great number of foods, not just milk. Homogenization is not essential, but it prevents the cream in milk from floating to the top, making the milk more uniform in texture.
In addition, milk may be processed into long-life UHT, powdered or canned products. Such processing affects the flavour but does not change the nutritional value significantly.
Ethical concerns of milk production
Balancing the milk needs of calves and farmers is tricky and controversial, and touches upon some ethical concerns. Some small dairies share milk between the calf and farmer; however, this is not normal practice as it is less profitable for farmers. Common solutions are to slaughter calves, send them to veal farms or raise female calves into dairy cows.
History of Milk
It is thought that milk was first collected for food 10,000 years ago, when livestock were domesticated. Ancient Greeks and Romans preferred sheep’s and goat’s milk, but also used camel, donkey and horse milk. For most of history, people had limited access to fresh milk, instead preserving what milk was available into cheeses, yogurt, and butter.
How lactose is removed from milk
Lactose-free milk is made by exposing milk to the enzyme lactase, which breaks lactose down into glucose and galactose.
Milk features in spiritual beliefs worldwide, often symbolising fertility and wealth. In the Bible, the promised land is called ‘the land of milk and honey’. In West Africa, it is believed that the world began with a drop of milk and, in Norse mythology, that the world was sustained by a cow in its youngest days.
Naturally, only babies carry the lactase enzyme needed to digest lactose in milk. Research shows the ability for adults to digest milk is due to a DNA mutation that occurred in Europe 5,000–10,000 years ago, which allowed adults to retain the lactase enzyme. This gave many people with European ancestry, the ability to digest milk into adulthood. Many people from Asia, Africa and South America do not have this DNA mutation and, therefore, cannot easily digest milk.
In the mid-1800s, breweries in America produced ‘swill milk’ as a side business, using leftover grains as dairy cattle feed. Swill milk was very unsanitary, contained additives such as chalk, and was reputed to cause illness and even death. An official investigation found that most childhood deaths of the time were caused by swill milk. By 1917, milk pasteurisation had become normal practice in America as a way to reduce bacterial contamination and disease.
Did you enjoy this article ‘What Milk is Made Of and How It’s Processed’?
If you’d like to learn more about the processed foods we eat everyday, please check out my non-fiction food comic book How Food is Made: An illustrated guide to how everyday food is produced. The book features 60 common foods, detailing their history and manufacturing process using illustrations and food infographics.
If you have ever wondered where factory food really comes from and how it is made, this book is for you. Don’t just take my word for it. Food critics and reviewers love the book too – check out critic reviews here. Find out more about the book here and read more free samples here.
Thanks for reading!
-Ayla Marika