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Gearhead: Pasteurization’s Place in Craft Beer’s Battle

Brewers looking to perfect their beer are proving that pasteurization has a place even at small breweries.

John M. Verive May 9, 2020 - 14 min read

Gearhead: Pasteurization’s Place in Craft Beer’s Battle Primary Image

The tunnel pasteurizer at Cycle Brewing in St. Petersburg, Florida.

In the spring of 1871, after France had lost to a coalition of German states in the Franco-Prussian War, the pioneering French scientist Louis Pasteur, like so many of his countrymen, was stricken with “revanchism”—a bitterness in defeat and a desire to exact revenge over the loss of Alsace and Lorraine. Pasteur wanted to strike his own blow against the Germans, one that would hit where it hurt most: in their beer glasses. Pasteur’s idea was to use his science to solve the problem of beer spoilage. Better French beer, his plan went, would help the French brewing industry grow into a global powerhouse that would put the breweries of Munich and Dortmund and Bamberg to shame.

He applied the scientific method to the often muddy, sour beers of the day, and while he didn’t like beer all that much, fragments of Pasteur’s notes from the experiments—housed at the Huntington Library in San Marino, California—reveal a hands-on approach to the problem of beer spoilage. On one page, dated March 7, 1871, Pasteur catalogs samples received from Veltins Brewery in the Ruhr Valley and includes not only gravity readings and observations of the beer under the microscope but also tasting notes. Other undated pages deal with bottles of Löwenbräu, Bass Ale, and an unnamed sample from the Belgian Ardennes. Pasteur may not have liked to drink beer, but as with French wine and the beetroot liquor before that, he did find a way to combat the spoilage microbes. He modified the process he patented in 1865 for “pasteurization” of wine, then shared his method with breweries around France, hoping they would brew a “beer of revenge” to overtake German beer as Europe’s standard. While his method worked, it was a Danish brewery, Carlsberg, that won the most renown with his techniques. At the newly commissioned Carlsberg laboratory, Emil Christian Hansen furthered Pasteur’s work and developed a method to refine the brewery’s yeast cultures, eventually isolating a single pure culture of lager yeast that would revolutionize brewing around the globe. Friday night would never be the same again.

Helping beer to travel across continents and arrive at far-flung markets in drinkable condition, pasteurization became widespread in 20th century brewing, decades before its adoption in dairy and juice industries. Unlike beer, which does not support microbes harmful to humans, fruit juice and especially milk can harbor deadly pathogens, and untold millions had been sickened before the government mandated pasteurization of milk. But be they harmless acetobacter or deadly Salmonella, pasteurization works the same way: liquid is heated until any microbes within are killed. How hot for how long varies by the liquid and the types of microbes targeted. In the brewing industry, there are two main methods of generating the desired amount of Pasteurization Units (or PUs—a measurement of how many microbes are destroyed): a high-temperature, high-speed process referred to as flash pasteurization; or batch pasteurization, which holds the product at a lower temperature for a longer time.

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