Mælk. Colourbox.com

Perforated lactic acid bacteria break down lactose in milk

Thursday 28 May 20


Christian Solem
Associate Professor
National Food Institute
+45 30 58 55 33
Researchers at the National Food Institute, Technical University of Denmark (DTU), have developed a food-grade method to perforate lactic acid bacteria naturally, which are useful for making lactose-free or sugar-reduced dairy products in a cost-effective and sustainable manner.

In recent years, the range of lactose-free products on the market has grown to meet an increasing demand from people, who cannot tolerate ordinary dairy products, because they are unable to break down the lactose (milk sugar) in the milk.

Researchers at the National Food Institute have discovered that lactic acid bacteria, which are present in yoghurt and other dairy products, are particularly well-suited for breaking down lactose, if they are first perforated. When the perforated bacteria are added to milk, the milk lactose can enter the bacteria, where it is broken down into its constituent sugars, glucose and galactose.

As such, the lactic acid bacteria replace the process, which normally takes place in the gut of people, who are able to tolerate lactose.

Natural, cheaper and sustainable

The commercial enzymes available on the market for splitting lactose in dairy products—the so-called lactases—are either produced using genetically modified microorganisms or microorganisms, which are not approved for use in food. However, the DTU invention provides a natural way of producing lactose-free products.

The researchers expect that their solution is cheaper and more sustainable to use than the existing one based on purified lactase enzymes. Production of commercial lactase enzymes involves an extensive and expensive purification process. Transport from the manufacturer as well as cold storage add costs.

The DTU solution makes it possible to generate the lactase at the dairy, from resources available at the dairy. The bacteria grow well in for instance whey permeate, a low-value byproduct generated by most cheese producing dairy plants. As such, the DTU solution thus can help increase resource utilization. 

The National Food Institute is taking out a patent on the invention and the dairy manufacturing giant ARLA is currently testing the method.

Sugar reduction

The DTU solution can help reduce added sugar in dairy products. When 70% of the lactose in a milk product is broken down, this corresponds to adding 20 grams of ordinary sugar per litre, which leads to a natural increase in sweetness. This can be particularly advantageous in the production of yoghurt, which often contains large amounts of added sugar.

Food technological advantages

Lactose can also cause headaches for ice cream producers, if they use milk powder in their products, since lactose has a tendency to form crystals in the ice cream. By breaking down the lactose in the milk before turning it into powder, the producers will be able to avoid this problem and achieve a better consistency.

Food producers will also be able to benefit from the fact that the two types of sugar—galactose and fructose—that are formed from the lactose are in total 60% as sweet as ordinary sugar whereas lactose on its own is only 16% as sweet.

Chocolate contains up to 10% lactose, which in itself does not contribute to the product’s sweetness. However, if chocolate producers choose to make the milk in their products lactose-free, they thereby achieve a greater sweetness in the milk, enabling them to reduce the amount of added sugar.

Read more

For more information about the lactic acid bacteria’s ability to transform lactose, read the researchers’ scientific article in the journal Applied Microbiology and Biotechnology: Efficient lactic acid bacteria cell catalysts as a cost-efficient alternative to purified lactase enzymes.

Read more about the National Food Institute’s biotechnological research in another news item from the institute: Bacteria increase the sweetness of milk sugar sixfold

The focus of the Research Group for Microbial Biotechnology and Biorefining at the National Food Institute is effective bioconversion of a wide range of renewable raw materials. Read more about the group’s work on the institute’s website.

Enzymes in a perforated lactic acid bacteria breaks lactose down into galactose and glucose. 

The enzymes in a perforated lactic acid bacteria breaks down lactose into its constituent sugars:
galactose and glucose. As such, the milk becomes lactose-free.

The value of the market for lactose-free dairy products

According to figures from Euromonitor, the global turnover for lactose-free products will have reached 77 billion Danish kroner by 2022.