The Eccentric Engineer

I'm fond of beer and, in small quantities, it's fond of me, but I have found myself wondering why is so much of the beer we drink today lager? That is all thanks to a 19th century war and a bit of vengeful chemical engineering.

Louis Pasteur is one of the greatest names in science, but this doesn't mean he was necessarily a very nice person. What particularly got Pasteur hot under the collar was Prussia and all things German. This was in large part due to the Franco-Prussian war, the outbreak of which in 1870 brought the building work on his new laboratory to a halt. It's understandable to take against people who invade your country and stop life-saving work on germ theory - particularly when the ensuing war sees your son enlist and fall dangerously ill with typhoid - but Pasteur took his hatred to extremes.

His abhorrence of all things Prussian took two visible forms. First, he insisted that every paper he published would contain the statement "Hatred towards Prussia! Revenge! Revenge!", which must have proved difficult for peer reviewers, but had little real impact. But the second form changed beer as we know it.

Until the 1860s beers were generally dark liquids, in which yeast fed on sugars from malted barley to produce alcohol and carbon dioxide, the bubbles of which made the yeast float on the top. But in the 1860s German brewers had engineered a small miracle. They cultivated yeasts that acted very slowly at very low temperatures and sank to the bottom.

These yeasts produced a lighter, straw-coloured beer that kept exceptionally well and was dubbed 'lager' - German for 'storage'. The result was a massive expansion in German beer production and its export across Europe. Pasteur saw his moment. He turned his genius to engineering the finest beer in the world - a beer that would be so good it would destroy the German brewing industry. He dubbed it 'The Beer of Revenge'.

He began isolating yeast strains that behaved like the German bottom-fermenting varieties but which acted faster and were more temperature tolerant so, in an age before refrigeration, could be used in climates warmer that Germany's. He also turned his mind to preventing spoilage in his 'superbeer', using skills developed in isolating anthrax to isolate the spoiling organisms that contaminated beer and then designing and patenting machinery and systems to keep them out of the brewing process.

After much experimenting, the type and process for making the Beer of Revenge was perfected. Pasteur now had his weapon and he immediately put it into action. Arranging a tour of European breweries which notably excluded any in German territories, he began freely sharing his secrets, notably with the Carlsberg Brewery in Denmark and Whitbread in England, although anyone could use his techniques provided they weren't German.

The result was spectacular for, although brewing was an age-old practice, very few brewers knew exactly what happened to turn their ingredients into beer. Pasteur did know, and he exhorted brewers to buy a microscope so they could examine their yeast and identify the thread-like fungi that often infected and spoiled it as well as recommending techniques for growing pure yeast strains and preventing their infection. He also wrote a book on the subject, which became a brewers' bible, but with the strict caveat that it must never be translated into German. It wasn't.

So did Pasteur get his revenge? Well it would be wrong to give all the credit for the brewing revolution to Pasteur but his Beer of Revenge did have a profound effect on the German brewing industry as other nations now had the techniques - and better ones at that - for making their own beer. These new, easy to produce and long-lived lagers would go on to take over the brewing world, hence their popularity in pubs to this day. But, as is so often the case with history, there was one small, unintended side-effect. With many German breweries now idle, their owners had to turn their machinery to other uses and found the perfect product in acetone. The acetone was needed for the production of cordite for the ongoing build up of German armaments that would later be unleashed on Pasteur's homeland at the outbreak of the First World War...

Winner of the issue 13 caption competition was Tom Peckham with "Third time lucky. The first two sank the ship!"

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