Yeast lab hunts for Bay Area brewing flavor

Yeast cultures being stored at Gigayeast, a Belmont company that produces commercial beer yeast. Yeast cultures being stored at Gigayeast, a Belmont company that produces commercial beer yeast. Photo: Paul Chinn, The Chronicle Buy photo Photo: Paul Chinn, The Chronicle Image 1 of / 5 Caption Close Yeast lab hunts for Bay Area brewing flavor 1 / 5 Back to Gallery

On weekends, Jim Withee jumps on his mountain bike and hits the trails in the Santa Cruz Mountains.

Instead of a backpack full of PowerBars, he carries sterile containers and forceps. With gloved hands, he plucks leaves and berries and takes them back to study in his lab.

If he's lucky, this wild local flora may contribute to making beer. But he's not looking for flavorings; he's looking for yeast.

Withee is the founder of Gigayeast, a startup commercial yeast lab in Belmont that supplies both professional and home brewers.

The microbiologist launched the company four years ago after working in risk assessment for the USDA - a job in which he provided information about food-borne illnesses and other microbial hazards.

"I love beer, and I just decided to quit cold and put everything I have into this," says Withee, who describes Gigayeast as a "midlife crisis of sorts."

Until recently, brewers mostly bought their yeast from a handful of big national outfits, like White Labs or Wyeast. But with the craft brewing field growing increasingly crowded, some brewers are looking to differentiate their beer by buying yeast from smaller labs, like Withee's.

At his small warehouse in an industrial zone hugging Highway 101, Withee isolates yeast cultures on petri dishes and grows them in steel tanks, with an eye toward creating something unique. Nowhere is this more evident than in his project to find beer yeast on plants from the Santa Cruz hills. Withee hopes he'll be able to discover a viable strain of Saccharomyces cerevisiae that can be sold to brewers looking to create a true Bay Area beer.

Expressing terroir

Increasingly, beer makers are taken with the notion of beers that express terroir. Craft breweries often seek out ingredients such as heirloom barley malted in small, local malt houses, or single-estate hops.

But yeast is a less explored frontier in the prospect of giving beers a sense of place. When you think of a truly local yeast, the lambics of Belgium's Senne River valley come to mind. These sour beers are naturally fermented using only ambient yeasts, taking advantage of local microflora much as Sherry relies on the unique yeasts of Jerez.

American craft brewers have been slow to develop similarly "wild" ales - almost all American-made sour beers are inoculated with commercial laboratory yeast. For years, the only truly wild ales that were made stateside and available in the Bay Area were the Resurgam, Coolship Red and Coolship Cerise beers from Allagash Brewing Co. in Portland, Maine, and Russian River Brewing's Beatification.

Part of this extremely limited availability has to do with the fact that making spontaneously fermented beer is harder than it sounds.

"There's this vision of these brewers just getting drunk and opening up the barn doors, but it's a lot more complex than that," Withee says.

With lambics, and other naturally fermented beer, the hot, unfermented wort is poured into what's called a "coolship," a shallow metal pan, and allowed to cool overnight, during which airborne yeasts and bacteria drop in and naturally ferment and sour the beer. The beer then has to age for up to three years and is typically blended to achieve something drinkable.

"You have to be willing to dump some beer," says Jason Perkins, Allagash's brewmaster. After all, you're letting nature take its course, and nature isn't always pretty.

Recently, however, a number of newer craft breweries, such as Jester King, out of Austin, Texas, and Crooked Stave in Denver have taken on the challenge. They installed coolships, and made spontaneously fermented beer.

Controlled approach

Two Bay Area brewers have adopted a somewhat less dicey and more controlled approach to using local yeast. Almanac Beer Co.'s Sourdough Wild Ale is partially fermented using a local sourdough bread starter. Withee's Gigayeast helped isolate the particular strain from a starter from San Francisco's Marla Bakery. Oakland's Linden Street Brewery has, similarly, brewed beer using yeast grown in its own lab from San Francisco's Tartine Bakery sourdough starter. In both cases, saccharomyces cerevisiae was found in the bread starters, then isolated and fed until it was strong enough to brew beer.

Sourdough has the added benefit of being a San Francisco specialty.

Withee, for his part, hasn't yet found any good brewers' yeast living on local berries or leaves. But he hasn't stopped trying.

"There's a lot of interest, and brewers are constantly asking me about it," he says. As long as the sun keeps shining, he'll hit the trails and keep sampling.