From The Toronto Star

Beer: It can’t be brew without these little critters

Yeast banks offer small breweries hundreds of strains to give unique character to a beer

When they’re looking at making a new beer, one of the first things brewers will do is head to the bank for a few hundred million.

Not dollars, yeast cells. In an age when there are banks for money, blood and heirloom seeds, you can also find yeast banks.

Yeast, which is necessary for fermentation, comes in hundreds of thousands of strains. It is Chris White’s goal to preserve and grow hundreds of kinds of yeast, each of which contributes its own unique character to a brew.

“We’re really preserving some history, because some of the strains we’ve got are very, very old. Probably hundreds of years, although it’s hard to say exactly,” White says. He was in Toronto for a Master Brewers Association of the Americas technical conference.

California-based White Labs, one of the world’s biggest yeast banks, has customers in 80 countries, including Canada.

White, who founded his company in 1995 after doing PhD research at a yeast laboratory in San Diego, has slightly more than 500 yeast strains available.

He has gathered the strains from breweries, other yeast banks and from bottle-conditioned beer (which still contains live yeast). They run the gamut from yeasts used to make English-style ales, to several strains of semi-wild Brettanomyces yeast, used to produce Belgian-style sour beers.

While hops and malt play a more obvious role in the flavour of some beers, yeast can also be a big contributor. White says the single-celled organisms are more than just a mere tool to ferment the malt’s sugars into alcohol.

“The range of flavours and aromas that different yeasts contribute is just amazing.”

Some yeasts used in English ales can lend a slight apple character to the brews, while German wheat beer yeasts can lend an aroma of bananas or cloves.

Some of the yeasts are good at producing relatively high levels of alcohol (some beyond 10 per cent), while others get tired out at much lower levels.

Being able to order up that kind of variety is a luxury brewers didn’t have before places like White Labs were around, says Brooklyn Brewery brewmaster Garrett Oliver.

“We simply had far fewer strains available. There were always methods of obtaining yeast strains. The new generation of yeast banks just makes things much easier,” says Oliver, who, along with White, presented a workshop on bottle-conditioned beer at the conference.

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