Raslysation: Meet the technology that could replace pasteurization

By Teodora Lyubomirova

- Last updated on GMT

Lyras' CEO Rasmus Mortenses stands next to the Raslysation Sirius
Lyras' CEO Rasmus Mortenses stands next to the Raslysation Sirius

Related tags Beverages Dairy Juice Sustainability Pasteurization Milk Nutrition

The non-thermal treatment method uses UV light to eliminate harmful bacteria from liquids while keeping nutrients, flavors and colors intact.

When French researcher Louis Pasteur found in the 1860s that heat treatment could eliminate microbes to prevent spoilage, he set in motion a process that would change the way beverages were preserved. While Pasteur was more interested in how his discovery could lengthen the lifespan of beer and wine, in 1886, German chemist Frans von Soxhlet was the first to suggest that pasteurization could be applied to milk. Five years on, he invented the first pasteurization device.

This all took place in the 19th​ century, and more than 130 years later, most countries in the world still require milk products sold to the public to be pasteurized. A tried-and-tested method, pasteurization also has little effect on nutrients, with riboflavin (vitamin B2) being the only vitamin that is significantly depleted in the process.

But what if manufacturers could get rid of spoilage bacteria without any heat treatment, making for a more energy-efficient alternative to pasteurization? Danish company Lyras thinks the answer is ‘raslysation’ - a patented, non-thermal treatment technology that applies specific UV wavelengths to treat bacteria and spores in opaque liquids, such as milk and juice. 

Gentle on proteins, vitamins and amino acids

“The technology works by combining a turbulent flow pattern with ultraviolet light sources to eliminate unwanted microorganisms in liquids and extend the shelf life of the final product,”​ a spokesperson for Lyras told DairyReporter. “Like pasteurization, raslysation intends to destroy or inactivate microorganisms that contribute to spoilage or risk of diseases. The removal of microbiology works in exactly the same way [as pasteurization]. UV light kills the microorganisms by altering their DNA. This changes their metabolism and replication, causing cell death.”

The name of the process pays homage to Rasmus Mortensen, Lyras CEO and inventor of raslysation; the word also contains ‘lys’, which means ‘light’ in Danish.

Since raslysation is a non-thermal process, it main benefit is that it ‘doesn’t harm whey proteins, and instead preserves the milk’s flavour and nutrient levels,’ we were told. Because of this ability to retain heat-sensitive nutrients, raslysation has been used for treating lactoferrin, one of the world’s most expensive milk proteins and a common ingredient in infant formula.

The method also offers a less carbon-intensive path to preserving liquid products. Lyras estimates that raslysation can cut energy consumption between 60-90% and water use by 60-80% compared to traditional techniques that require the product to be heated, then cooled again. The technology can also replace microfiltration, a physical filtration process that typically requires workers to manually pass liquid through filters to separated microorganisms from the fluid. Copenhagen-based biotech company Novozymes is one firm that has recently invested in a filtration replacement system from Lyras.

“Lyras is quite literally shining a light on an industry that has been a source of high levels of water and consumption, as well as a significant producer of CO2,”​ Mortensen commented. “Our goal is to support the processing industry to reduce energy and water consumption and usage, and ultimately create a better, more sustainable way to produce products that millions of people use and consume every day. This is especially important during the energy crisis, plus an increased focus on the shelf life of food products.”

From milk to enzymes

Raslysation can also be used to preserve other beverage types, such as fruit juice and can also find application in the industrial fermentation sector to treat enzymes. “With juice, raslysation improves sensory perception to make the product more enjoyable,”​ the company representative told us. “When you avoid high temperatures, you achieve a much gentler treatment, which naturally preserves the product’s natural characteristics, such as colours, nutrients, and flavor.”

The technology comprises a standalone unit with PLC, HMI and MCC panels and a feed unit. It is designed with no glass-food contact for improved safety and is fully scalable – a single unit can handle liquids up to 28,000 liters per hour, depending on the opacity of the liquid. “The system used for each product is specifically designed for the customer in question to ensure a perfect fit,”​ a Lyras spokesperson said.

While the potential for raslysation as an alternative to pasteurization exists, there are still limitations over how and where the technology can be used. For example, DairyReporter understands that one Lyras client – dairy co-op Arla Foods in Denmark – utilizes the tech ‘to keep the bacteriology under control in our brine’ at least one of its farms, rather than to pasteurize milk.

Asked where the company is at with regulators, the Lyras spokesperson said: “There is no specific regulation at EU level for the use of UV technology. However, Germany has a special regulation in place limiting the use of our technology, which would require specific approval for some purposes. We are involved in research projects for full validation and legal approval of raslysation as an alternative to the pasteurization of milk and whey. We are working with local experts to assure legal approval outside the EU.”

Meanwhile, the system has already been sold to companies in the US, Australia, Spain, Sweden and Denmark that operate within the dairy, juice and industrial fermentation industries. Now, it is entering the UK and Ireland market, which has shown ‘huge potential’ according to Lyras. “The rising energy prices in the UK mean that our technology can ensure faster ROI for our customers. At the moment, we do not have customers in the UK - however, our technology is deployed by Arla Foods in Denmark, so we hope that this may result in deployment in the UK.”

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