Brewers of alcoholic beverages aren’t just making drinks — they’re managing, and sometimes even breeding, specialized herds of tiny lifeforms which perform specific functions: yeasts.
One function that yeast can be bred for is flocculation, which means “grouping together in clumps.” Different strains of brewers yeast do it at different times. This isn’t just a behavioral trait; yeasts that stick together quickly do so because they grow little strands called fimbriae on the outside of their body. These tangle together and make the yeasts clump. When they clump, they usually fall to the bottom of the tank.
Most beer yeasts clump, but they clump at different points. High flocculation yeasts clump together within five days, and precipitate to the bottom of the fermentation tank, slowing the process of fermentation. These yeasts haven’t consumed much sugar during their short single lives, so they make beers that tend to have more sugar left in them. Low flocculation yeasts will stay in the beer for two weeks, and give it a “powdery” taste.
Then there are yeasts that don’t flocculate at all, and need to be filtered. Sake is one of the alcohols produced by non-flocculating yeast. But just because the yeast wasn’t bred to clump together doesn’t mean the yeast in sake wasn’t carefully husbanded. In fact, most of the sake out there today is produced by a strain of yeast produced in the 1960s in a cultivation breakthrough. The sake at the time was bubbling too much, making it a hassle to produce. Hiroichi Akiyama, a scientist who had studied yeasts, knew that yeast which didn’t bubble much during the fermentation process tended to attach itself to the foam it produced. To cultivate this strain he essentially raised generation after generation of yeasts, carefully separating out the yeast that clung to the foam and culling the yeast that stayed in the tank. After repeated husbandry, he managed to breed a sake yeast that produced the same alcohol, without the bubbles.
Yeasts are fungi, not animals. Still, it’s interesting to think of brewers not as producers of alcohol, but as ranchers, raising millions of livestock that needs to be protected, fed, and successively bred to create better and better stock.
Top Image: Public Domain, Wiki Commons.