Choosing a yeast strain based on name can be a great way to begin – Czech lager for Pilsner, for instance. But certainly, on top of the name, you have to look into other factors before deciding if the strain you’ve got is actually what you want.
Below are performance indicators that will help you pick the right yeast strain:
Attenuation is simply the percentage of available wort sugars that is actually fermented by a yeast strain. The usual value range is from 72% down (minimum) to 78% up (maximum). Attenuation though is largely an issue of style and preference. The secret is to choose a yeast strain with attenuation that is consistent with your taste.
Flocculation is the readiness of yeast cells to clump together and settle at the bottom of the fermentor after achieving a critical mass. Some strains known to be highly flocculent are British strains – the moment the yeast cells clump together on the fermentor’s floor, it breaks into chunks. Weizen yeasts, on the other hand, are famous for low flocculation, which means they usually remain in suspension. Sometimes, separating the yeast even calls for the beer’s refrigeration or centrifugation. The best thing to do is to choose a strain whose flocculation is right for the beer you want to brew.
Alcohol tolerance is how much alcohol is tolerated by a yeast strain before it no longer works. Over the years, brewers have pressured yeast strains to survive in various conditions. And clearly, yeast strains now used to make high-alcohol beers have stood up to the challenge. Whatever the alcohol level you want for your beer, choose a strain that can survive beyond it.
Range of Temperature
In the context of yeast strains, temperature range is the range of temperature that a certain yeast strain is expected to act best. Most, if not all, yeasts ferment in temperatures higher than their limits, but the results will be hardly the same for each one. Hence, you’ll want to know the best temperature range for your chosen strain for two important reasons – first, so you can use equipment that ferments at the right temperature, and second, so you can adjust your fermenting temperature, depending on the flavor you want for your beer.
Lasty, while the first four indicators we have mentioned are all measurable, sensory profile is subjective. It all boils down the person who does the “sensing.” In other words, you have to brew a certain yeast strain if you want to get its sensory profile.