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Short, but intensive: beer pasteurisation can be done quite differently

Tradition and brewing go together like needle and thread. That however does not mean that question marks should not be raised from time to time. Roland Feilner and Thomas Oehmichen have done exactly that, and in doing so they have made an interesting discovery.

Most beer is pasteurised (briefly heated) after brewing. This is done primarily to kill microorganisms and extend shelf life. With wheat beer and other naturally cloudy beer, pasteurisation is done for another, and equally important, reason. Specific proteins are denatured, and that can have a positive effect on the characteristic clouding. However, care must be taken during heating to avoid the formation of unwanted macromolecules, and that inevitably makes pasteurisation a balancing act. This is particularly the case with wheat beer. The temperatures needed to produce clouding stability are higher than what would otherwise be necessary merely to extend shelf life.

Thomas Oehmichen and Roland Feilner

New process, new equipment

“Wheat beer is almost always over-pasteurised,” explained Roland Feilner, Head of Components Processing Units. To change that, he and Thomas Oehmichen developed a new pasteurisation process. The beer is heated to a higher temperature than was the case in the past, but only for ten seconds instead of the usual thirty seconds. This process not only has a new name (Express Pasteurisation), but changes have been made to the equipment as well. The length of the heat retention section in the VarioFlash B has been reduced by approximately two-thirds, and the flash pasteuriser as a whole is much more compact. “As a result, the unit does not have to be disassembled for shipment and is ready to use when it arrives at the customer site,” reported Thomas Oehmichen. The smaller size also has benefits during ongoing operation, the primary advantage being lower maintenance costs. The flash pasteuriser no longer has to be mounted on top of the pasteuriser which takes considerable effort and makes access to the components more difficult. As attractive as these cost advantages are, beer lovers and brewers will be very interested to learn about another effect of Express Pasteurisation.

100 metre dash instead of a marathon

“In pasteurisation, it is important that all particles in the beer remain in the flash pasteuriser for the same amount of time if possible,” explained Roland Feilner. “Otherwise, it can happen that one particle is heated for too long which damages it, while another is not fully heat treated.” Compared to the conventional 30-second process, with Express Pasteurisation the difference between the fastest and the slowest particles is substantially less. Again, the reason for that is the shorter heat retention section. Thomas Oehmichen gave the following explanation: “You can think about it as being something like a running event. The longer the distance, the more the field of runners becomes strung out. The distance between the first and last runner in a marathon is far greater than in a 100-metre dash”. In the pasteurisation context, this means that beer molecules receive more even treatment, which enhances the quality and safety of the end product.

Worthy of an award

Even if he initiated the project, Roland Feilner does not wish to claim credit for the underlying idea. “This method has been under discussion by experts for a relatively long time, but a practical demonstration that it actually works has been lacking.” To bridge this scientific gap, Feilner and Oehmichen conducted an extensive series of trials at the Bischofshof brewery in Regensburg. It took them nearly six months to find the right time-temperature combination and run experiments to verify the technique. As a reward for all this ingenuity, there will be one of the coveted FoodTec Awards in Silver at the Anuga FoodTec trade fair in March. It is nice that their efforts are appreciated, but there is another reason why the award is particularly satisfying. “Express Pasteurisation is the best example of how techniques that have been cast in stone for many years can still be improved,” observed Feilner. “The FoodTec Award shows our customers that Krones has the innovative energy to do exactly that.”

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