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Caffeinated Beer, Manure-Preserving Sauerkraut

by Sarah Everts
December 17, 2012 | A version of this story appeared in Volume 90, Issue 51


Credit: Shutterstock
Beer: Now with caffeine.
A photograph of a blonde-haired man in lederhosen holding a large mug of beer as if giving a toast.
Credit: Shutterstock
Beer: Now with caffeine.

It may not be known as a culinary Mecca, but Germany considers its sausage, sauerkraut, and beer as sacrosanct. Which is why recent experiments on the country’s holy food and drink sound a tad irreverent.

Our story begins on the Weihenstephan campus of Munich’s Technical University in deep Bavaria, not far from a monastic brewery that dates back to A.D. 1040.

There, undergraduate student researchers have slipped biosynthetic genes for caffeine into beer-brewing yeast so that one day we may drink a pint of beer and defy sleep at the same time. The team has also inserted into the yeast the genes required to make the citrus flavoring limonene. And they’ve tinkered with genes to make xanthohumol, an anticancer agent that additionally blocks hot flashes in menopausal women.

In the U.S., microbreweries have paved the way for quirky beers with unusual ingredients, but in Germany, this project is radical.

For one thing, back in 1871, Bavaria refused to unify with the rest of Germany unless the country’s other states enacted the Reinheitsgebot, a 16th-century beer-purity law that dictated that the treasured golden beverage could contain only water, barley, and hops. Certainly not caffeine.

Although the Reinheitsgebot is no longer a strict law in Germany (it’s been superseded by the European Union’s regulations), many breweries abide by the centuries-old mandate to satisfy Germanic palates.

But the project is also radical because genetically engineered food is controversial in Germany. Curiously enough, though, the new genetically engineered yeast could provide a loophole for German brewers who might want to experiment with beer additives without disobeying the Reinheitsgebot, says Arne Skerra. He’s the biological chemist who supervised the student project in Bavaria.

According to Skerra, yeast is inherently necessary for old-school beer making and thus allowable by the Reinheitsgebot. So in principle, brewers of the future could slip all sorts of interesting flavors into beer through yeast. They’d still be able to add the Reinheitsgebot seal to their bottles because the flavors wouldn’t be inserted as additives.

It’s a toss-up whether German consumers would be more comfortable with genetically modified beer over chemically enhanced beer. Flavor might trump fear, or maybe not. Unfortunately, the beer is not yet ready for tasting, so stay tuned.

If beer is the holiest of beverages in Germany, sauerkraut juice is substantially less sacred. Yes, sauerkraut juice. So much cabbage is fermented in Germany, there’s a glut of the leftover liquid that manufacturers try to sell. Rumors abound that sauerkraut juice is good for digestion, but it’s hard to find anyone who admits to liking the stuff.

Credit: Shutterstock
Sauerkraut juice: Good for digestion—and manure.
Photo of a bowl of sauerkraut garnished with parsley, two glasses of sauerkraut juice, and a quarter head of cabbage.
Credit: Shutterstock
Sauerkraut juice: Good for digestion—and manure.

Luckily, there’s now another solution for the cabbagey leftovers, courtesy of Austrian entrepreneur Thomas Rippel. Based in Zurich, Rippel presented his juicy idea at the Falling Walls conference in Berlin last month.

To prevent the vast number of manure pools that grace Germany’s farmland from rotting, Rippel proposes pouring sauerkraut juice over the potential crop fertilizer.

Here’s a little manure math: One cow produces a ton of manure in a year, Rippel says. Manure is great for fertilizing crop soil. But the nutrient-rich poop tends to decompose in the specialized outdoor manure pools used for storage. In fact, just in Germany, some 600,000 tons of ammonia evaporates from degrading manure pools every year, the entrepreneur explains. Poof, there go the nutrients. Plus, the pools are stinky.

When Rippel added sauerkraut juice to some manure pools, however, the rotting stopped. Something—still to be determined—in the liquid, which is laden with lactic acid bacteria, blocks microbes from degrading the manure.

Sauerkraut and cow poop. Beer and caffeine. The Newscripts gang wonders about the future of Germany’s treasured sausages.

sarah everts wrote this week’s column. Please send comments and suggestions to


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