Profiles in brew: White Labs Pure Yeast & Fermentation

The magic behind beer’s crucial ingredient

Susan France

People think hops,” JoAnne Carilli-Stevenson, White Labs’ global key account manager, tells Boulder Weekly. “Whenever they think beer they think hops. Very few people actually think yeast.”

“Yeast is not the last-minute addition to the brewing process,” Shawn Donahue, White Labs’ tasting room assistant, adds. “I always tell people: Brewers make wort, yeast makes beer.”

Making beer is a rather simple process: malted grains are mixed with hot water, converting the starches from the grains into a sugary liquid mixture called “wort.” Hops can be added, or not, to provide flavor and aroma, but it’s still not beer. Yeast needs to be added, or “pitched,” to use brewing terminology. Yeast gobbles up the sugars and produces alcohol and carbon dioxide. This is called fermentation, and fermentation is where White Labs comes in.

Started in 1995 in San Diego, California, White Labs Pure Yeast & Fermentation stands at the intersection of science, education and craft. Now with production facilities in San Diego, Copenhagen, and Asheville, North Carolina, White Labs produces unique yeast strains for commercial and homebrewers across 75 countries.

“On any given week [we] might be producing 100-150 different strains,” Carilli-Stevenson says.

But White Labs isn’t just a company for brewers; they’re also dedicated to educating beer drinkers on what yeast adds to the beer they’re drinking. That’s the goal behind White Labs’ Boulder taproom, which offers customers a chance to sample and compare different yeast strains used in base beer styles.

Take White Labs’ Oat India Pale Ale, either with the California Ale V Yeast (WLP051) or the Antwerp Ale Yeast (WLP515). The former ferments the beer clean and produces a fruity aroma, like you would expect from an American IPA; the latter adds aromas of fennel, bread and a little bit of spice, just the flavor profile you’d expect from a Belgian beer.

These two are just the tip of the proverbial iceberg. White Labs offers two Frankenbeers, beers Donahue describes with great relish.

“FrankenStout and a FrankenIPA; for both of those we took the 96 core strains and then just threw them all in one beer,” Donahue explains. “It comes out different every time. Certain strands will take over and the balance shifts from keg to keg, even as you’re drinking it.”

Those constantly shifting balances, which continue to develop as the beer is allowed to warm in the glass, are part and parcel of White Labs’ liquid yeast. For the brewing process, yeast can either be dried or liquid, but if you want the most bang for your buck, liquid is the way to go.

“Liquid yeast has 300 different ester flavor profiles,” Carilli-Stevenson explains. “So, dried yeast, there are only a few strains that have been successfully dried and work very well in the brewing process. … I think you have a variety of 10 to 12. And in liquid yeast, [it’s] basically infinite.”

And with infinite variety comes vast potential.