Yeast-hopped Beer Is Real And Itís Much More Sustainable
BY LEE MATHEWS

Back in the 1500s, the German Beer Purity Law declared that brewers could use only three essential ingredients: water, barley, and hops. Yeast wasnít on the list because its role hadnít been identified yet.

Louis Pasteur finally made the connection in the mid-19th century. Today, brewers are using countless different strains of yeast ó including some from pretty unexpected sources ó to craft their complex concoctions.

Now thereís even a yeast that does double duty. Thanks to the work of a team of scientists from U.C. Berkley, yeast can now impart aromas and flavors that mimic those of hops.

The result: a beer that passed a blind taste test that tapped 27 brewery employees with flying colors. Berkleyís beer was actually rated hoppier than the traditionally-brewed beer they used for comparison.

They did it by borrowing a bit of genetic code. The team used CRISPR editing (specifically CRISPR-Cas9, which was developed at Berkley) to insert genes for linalool synthase and geraniol synthase.

Geraniol imparts floral or fruity aromas to a beer and is found in hop varieties like Cascade, Citra, Centennial, and Pacific Hallertau. Linalool brings citrusy and floral notes, and itís considered to be a good indicator of how hoppy a beer is.

By brewing with yeast that can produce those compounds, the Berkley team greatly reduced the amount of hops needed they needed to use. Hops were used only in the wort, when they add bitterness without impacting the beerís flavor.

Swapping their engineered yeast for additional hops can make the brewing process more sustainable. Growing the hops needed to produce a single pint of beer requires about 50 pints of water. The characteristics of hops can also change dramatically from one season to the next.

That wouldnít be a problem with yeast, which can consistently crank out substances from artificial vanilla to insulin ó and more recently vegan eggs, cheese, and leather.

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