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Filtered beer: Don’t fear the clear

Why is that “natural, handcrafted” beer filtered? An explainer.
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Let’s get this out of the way: That beer in your hands is probably not 100 percent “natural,” nor literally “handcrafted” by artisans. It might have sulfites, for example. Computers most likely helped to automate things.

And something else: That liquid was probably—but not necessarily—filtered, somewhere between fermentation and filling up that can, bottle or keg.

So let’s learn a few things about these little industrial factories that use the word “craft.”

The beverage industry loves this cliche: “We drink with our eyes first.” The idea is simple: If it looks good, we’re more likely to think it tastes better, and we’re more likely to buy it. As it turns out, the folks pulling the levers are pretty sure that we like our drinks as translucent as fine jewels.

The usual way to accomplish that is to push fermented beer through something with lots of tiny holes—tiny enough to keep out those messy, unwanted particles that can make a beer hazy or cloudy. This affects the character of the beer, for better or worse, depending on the recipe and how finely it is filtered.

There are many types of filters, all of them weird to anyone who has never seen one. Some look like space-age stacks of plastic disks, encased in stainless steel, something like a prop from the Death Star. Sometimes the filters are packed with naturally occurring fine powders. The two most common types are diatomaceous earth—made from teeny-tiny algae fossils—and perlite, a type of volcanic glass. Diatomaceous earth carries some occupational safety baggage. If inhaled—a workplace hazard—it is carcinogenic. Perlite can also damage the lungs but is not known to cause cancer, one reason why hundreds of U.S. breweries choose it.

One of them is Titletown Brewing in Green Bay, Wis. “The perlite provides a pretty coarse filtration,” says brewmaster David Oldenburg, “enough to remove most of the yeast, but not enough to strip flavor.”
Even breweries that filter don’t necessarily filter all of their beers. Your corner brewpub may, like Titletown, filter a pale ale for “polish” while leaving that hazy wheat beer alone. It depends on the recipe, and the brewer’s discretion. “If a beer will taste better with yeast in it, we skip filtration,” Oldenburg says. “Otherwise, we filter.”

Diatomaceous earth may have other issues due to its mineral nature. Last year a widely reported German study blamed it for increased levels of arsenic in beer—in some cases, more than twice the amount allowed in drinking water. In that sense beer shares the wider concerns of the food industry: Improved detection methods find more traces in what we consume, while the long-term effects of low-level exposure are not yet well understood.

For many decades, diatomaceous earth has been one of the most common ways to filter beer in the United States. Exactly how common it is today isn’t clear; there are no recent surveys of the country’s 3,000-plus breweries, even as they multiply, with new and smaller outfits having to make practical, cost-effective choices to get up and running.

It’s worth noting many craft breweries avoid filtering or keep it to a minimum, while some—like Sierra Nevada and Boulevard—add yeast back into the bottle for complexity and longevity.

Making a clear beer is plain old science and engineering. Making one that is attractive not just visually but in overall character—that is more of an art.

In the end, drinkers decide. We vote in the usual way.

 

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One Comment

  • Burt Nehmer says:

    Heh, you didn’t mention the katest trens, centrifuge. That’s the best way and has less loss of luquud with great flabor and clarity. I know that Allagash, Hangar 24, Ninkasi and Upslope have one. There are probably more.

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