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.
Here are performance indicators that will help you decide on a yeast strain:
Attenuation is the portion (%) of wort sugars available that a yeast strain actually ferments. The usual value range is from 72% down (minimum) to 78% up (maximum). Attenuation though is largely an issue of style and preference. The idea is to select a yeast strain that comes with a level of attenuation that is perfect for your palate.
Yeast cells’ tendency to form a cluster as they reach a particular mass and settle on the bottom part of the fermentor is called flocculation. British strains are known for being flocculent: once fermentation is done (sometimes, this happens prior!), yeast cells transform into a compact cake on the floor of the fermentor and then disintegrate. On the contrary, Weizen yeasts are popular for being not so flocculent, meaning they typically stay suspended. Sometimes, separating the yeast even calls for the beer’s refrigeration or centrifugation. The best option is the strain whose flocculation is the best fit for the beer you plan to brew.
How much alcohol it takes to stop a yeast strain from working is known as alcohol tolerance. Over the years, brewers have pressured yeast strains to survive in various conditions. And apparently, those yeast strains that are used to manufacture high-alcohol beers have measured up to expectations. Regardless of how much alcohol you want to put in your beer, pick a strain that can stand 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.” Which means, if you are interested in a certain yeast strain’s sensory profile, the only way to get it is by brewing it.