Milk. It’s hard to imagine living without it. From a warming bowl of porridge in the winter or a skinny pumpkin spiced latte, to an ice-cold glass of chocolate milk. But sometimes you want something a little less creamy and a little healthier. Skimmed milk is the perfect alternative to whole milk. It’s made with less fat – as little as 0.1% and the best part is that it still retains much of the nutritional benefits of other milks.
Despite the common myth, skimmed milk is not made by adding water to milk. Instead it’s produced by ‘skimming off’ some of the fat that makes whole milk creamy. To find out how skimmed milk is produced, keep reading.
A Short History of Skimmed Milk
Time for a milk break! (Photo: Johnny Greig via Getty Images)
Milk has been with us for around 10,000 years. The earliest forms of milk were most likely obtained from sheep or goats. By 4,000 BC, milk was being produced in many parts of the world, including Europe, India, and China.
In the nineteenth century, new manufacturing processes and faster modes of transport meant that milk could be transported around the country without spoiling. As the age of refrigeration and pasteurisation arrived, it could be stored for longer and became a daily staple.
Skimmed milk – traditionally a by-product of butter processing – used to be added to feed for pigs, chickens and calves because it was a high-protein replacement for far more expensive animal feeds. Before the Industrial Revolution, the process of producing skimmed milk was relatively simple. Whole milk would be left to sit until the cream rose to the top and could be removed. This is because cream is less dense than water, so it floats. However, the process of how semi-skimmed and skimmed milk is produced in the 21st century is both more complex and more automated.
Today, skimmed milk itself represents around 12% of the UK milk market, while semi-skimmed is around 60%. Here, we’ll answer the questions of ‘how is skimmed milk made’ and ‘how is semi-skimmed milk made’.
How Skimmed Milk is Made
Empty bottles being filled with milk on a production line (Photo: Johnny Greig via Getty Images)
First of all, we’ll examine how milk is produced, then we’ll explore in further detail the process of how skimmed milk is produced after it arrives at the processing plant from the dairy farm.
Pasteurisation
Once the untreated milk has been delivered to the processing plant, the initial step in modern factory-based milk production is pasteurisation. To kill off any harmful bacteria, milk is pumped through a pipe at 72°C for 15 seconds. The temperature is very carefully monitored in case it needs to be reprocessed. This is one of the most important parts of the modern process of how skimmed milk is made.
Homogenisation
At high pressures and by passing it through small holes, the milk fat particles are broken down and the fats are more evenly distributed throughout the milk. At this stage, the milk can be cooled down to 4°C.
Fortification
Fortifying milk is the process of adding nutrients that are important for human health such as vitamins A and D and calcium. It also increases the shelf life of milk and makes it more resistant to spoilage. There are several methods of fortifying milk, but the most common method is to add powdered vitamins and minerals to pasteurised and homogenised milk. Fortifying milk in this way is a simple and effective way to improve the nutritional value of milk without changing its taste or texture.
Skimmed & Semi-Skimmed Milk
But how is low fat milk made? The answer to the question ‘how is skimmed milk made’ involves an important extra step. Before the milk can be produced, the cream must be spun off. This is done by a process called centrifugal separation. The milk is spun very fast so that the fat content separates and can be sifted out. Once this is done, the milk can be checked carefully to ensure the fat content is at the right level for sale. For skimmed milk the fat content should be between 0.1% and 0.3%. Asking ‘how is semi-skimmed milk made’ offers up exactly the same answer. Semi-skimmed milk is made by exactly the same process – centrifugal separation – but the end product should contain around 1.7% fat. This is almost half the fat of whole, or full fat, milk which has a fat content of 3.5%.
A Plethora of Products
Whilst the thinner consistency of skimmed milk often makes it less useful in cooking, it’s ideal for foaming drinks such as lattes due to the protein content, which helps to stabilise the foam. Therefore both skimmed and semi-skimmed milk are used in a wide variety of milk-based products.
