There's nothing quite as refreshing as a glass of beer on a hot day and nothing more disgusting than discovering that the beer has gone off in the bottle, leaving a sour, cloudy mess. To save innocent palates and Sunday barbecues, the Fraunhofer Institute is developing a new polymer powder that can quickly detect pathogens in beer before they can ruin the brew.

To ensure that the finished product is drinkable, breweries invest heavily in quality control systems. Because beer is a "living" product produced by fermentation, contamination by microorganisms is a major concern because in the nutrient-rich beer, a few bacteria or other microorganisms can rapidly turn a refreshing pint into a nasty experience.

The conventional way of detecting bacteria is incubation. In this, samples of beer are filtered through a membrane and the residue collected is placed on agar plates. After incubation, any bacteria colonies that form are separated out and cultivated again until pure strains are produced that can be identified under a microscope. It works, but it's very time consuming because the incubation takes two to five days, so by the time the bacteria is detected, it may be too late to save the affected batch.

At the Fraunhofer Institute for Applied Polymer Research in Potsdam, scientists are working on a new test for beer pathogens that relies on a polymer powder. The powder, which was created in collaboration with GEN-IAL of Troisdorf, is made up of particles measuring 100 to 200 microns and is added directly to a liquid beer sample. The polymer is engineered so its surface interacts with the membrane of the microorganisms and clings to them. The result is that the powder soon gathers a concentrated sample of the pathogens, which can be separated from the liquid using a special system and studied under a microscope.

The functionalized polymer powder disperses in water

According to Fraunhofer, the polymer has a number of advantages aside from time savings. The system can handle liquid samples 30 times larger than traditional membrane filtration and incubation, which makes it more likely to detect contaminants that may only be present in small numbers. In addition, it can handle many beverages that can't be easily filtered.

"Membrane filtration is not suitable for the quality control of beverages such as fruit juices, milk, cola and red wine. They contain so much solid or suspended matter that the filter clogs quickly," says Andreas Holländer, a scientist at Applied Polymer Research.

Fraunhofer says that the polymer is currently undergoing pilot plant testing at GEN-IAL and will be available later this year.

Source: Fraunhofer

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