How Is Lactose-Free Milk Made?

Put simply, lactose-free milk is normal cow’s milk that has had a type of sugar called lactose removed. It contains the same nutrients as regular milk but is much easier to digest for people who are lactose intolerant. Read on to find out how lactose free milk is manufactured.

Engineering How It’s Made
20 September 2022

To digest and absorb lactose sugars, our bodies need an enzyme called lactase which breaks lactose down into two small molecules called glucose and galactose. These two smaller molecules are then easily absorbed into the small intestine.

However, if our bodies don’t produce enough lactase, drinking milk can result in discomfort such as stomach aches and bloating. It is believed that as much as 65% of the world’s population have some kind of difficulty absorbing lactose, which is why scientists have developed milk with the lactose taken out. So how do they make lactose free milk?

A Short History of Lactose Free Milk

Lactose intolerant (Photo: George Mdivanian / EyeEm via Getty Images)

An intolerance to lactose has seemingly been around for as long as humans have been drinking milk. It’s even believed that the most famous prehistoric mummy – known as Ötzi who lived around 5200 years ago on the border of Italy and Austria – was lactose intolerant.

It was in 1633 that Italian physician Fabrizio Bartoletti first isolated lactose in milk. It was identified as a sugar almost 150 years later by Swedish-German chemist Carl Wilhelm Scheele. Over the course of the next century, the two molecules known as glucose and galactose were isolated – the latter by Louis Pasteur.

Fast-forward to the early 1980s and third-generation dairy farmer, Alan Kligerman, wanted to produce a type of milk that could be easily ingested by those with a lactose intolerance. He sought out a chemist who worked at the United States Department of Agriculture’s research arm by the name of Virginia Harris Holsinger, who invented a process which broke down lactose into glucose and galactose.

By 1985, the technology was produced to make lactose-free milk on an industrial scale, but how is lactose free milk made?

Lactose Free Milk - The Manufacturing Process

Tank and automatic cow milking for milk production (Photo: Christian Ender via Getty Images)

The first part of the process of making lactose-free milk is the same as that used in the process of producing ordinary cow’s milk, that being the milking process itself whereby cows are milked using vacuum machines. Once the milk is ready, it needs to be treated to remove the lactose sugar and this is where the question of ‘how is lactose free milk produced? comes to the fore.

The Filtering

The first step is to pass the milk through a filter, which sifts out about 40% of the lactose. This does not filter out any of the other ingredients so the levels of proteins, vitamins and calcium are the same in lactose free milk as standard cow’s milk.

Adding The Lactase

The enzyme Lactase is then added to the milk and mixed slowly for up to 24 hours in a large vat. During this process, the lactase separates the lactose into glucose and galactose, which are easier components for our intestines to absorb. Once the lactase has been added, the milk is pasteurised – heated – to ensure the lactase enzyme is deactivated.

The Testing

The final  – and most important – stage in the process of how lactose free milk is manufactured is the testing. The milk must be carefully tested to ensure there is no lactose present. Once fully processed, the milk should have a presence of no more than 0.01% lactose. So, not quite zero, but this low amount is very rarely detected by the body. This is the final step in the process of how lactose free milk is made.

A Longer Lasting Product

Lactose free milk on the supermarket shelves (Photo: SolStock via Getty Images)

Once it gets to our supermarket shelves, lactose-free milk actually lasts longer, as the sour taste of spoiled milk is due to the lactose being broken down into lactic acid. Lactic acid is also the reason why cow’s milk curdles and goes lumpy when it expires.


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