WASHINGTON – A beer drinker looking to quench his thirst might not give a second thought to what microbiologists call “the master ingredient” in beer.
“I think the typical consumer doesn’t really think about the yeast, but if it goes wrong they’ll definitely know it was a yeast problem,” says Rebecca Newman, quality control manager for Dogfish Head Craft Brewery.
Newman was recruited by Anheuser-Busch right out of college in the mid-’80s, armed with a degree in food science and technology.
She and Charlie Bamforth, Ph.D., Anheuser-Busch Endowed Professor of Malting and Brewing Sciences, University of California – Davis, will be speaking Thursday evening at the headquarters of the American Society for Microbiology, in an event called “The Microbiology of Beer.”
“I look at yeast as being the conductor of an orchestra, with all the ingredients as the instruments that would go into making the different beers,” says Newman.
And I look at the yeast as conducting all those ingredients to come up with a final beer flavor,” says Newman.
Newman says unique strains of yeast make unique flavors.
The yeast’s the thing
“A Belgian-style yeast makes a beer that has the flavors of green bananas and cloves. The beer doesn’t have green bananas and cloves in it, it’s just the flavors from the yeast,” says Newman.
A different kind of beer would require a different yeast, according to Newman.
“If you were drinking an Oktoberfest beer, you would want a yeast that has a mid- palate resonance, you wouldn’t want it yeast-forward, because an Oktoberfest is very malt-forward,” says Newman.
Yeasts are members of the fungal kingdom, and there are approximately 1500 species of yeast.
The two major kinds of brewer’s yeast are ale yeast and lager yeast.
“The brewer has lots of tools to modify the flavor,” says Newman. “It’s not only the ingredients, it’s the temperature of the fermentation. Too fast, too hot fermentation the yeast will stall out or produce off-flavors.”
“You want to coddle your yeast to start, and then watch them through their fermentation profile,” says Newman.
Newman says home brewers often compare notes on strains of yeast and fermentation.
Professional brewers are less likely to share the yeast details.
“Sometimes you just don’t discuss what your proprietary strain is, because it’s a strain you’ve worked on to develop, in house,” says Newman.