Going by name – for example, Scottish ale for wee heavy – can be a good way to start selecting a yeast strain. But definitely, besides the name, there are other things that affect whether or not a certain strain is what you’re looking for.
These are the performance indicators that can help you determine which yeast strain to get:
The amount of available wort sugars (expressed in percentage) that a yeast strain actually ferments is known as attenuation. The usual value range is from 72% down (minimum) to 78% up (maximum). However, attenuation essentially depends on the brewer’s style and personal preference. The secret is to choose a yeast strain with attenuation that is consistent with your taste.
Flocculation refers to yeast cells’ ability to join together and, after attaining a crucial mass, lower itself to the bottom of the fermentor. 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. Weizen yeasts, on the other hand, are famous for low flocculation, which means they usually remain in suspension. In extreme cases, the beer must even be put in the fridge or centrifuged before the yeast comes off. In any case, pick a yeast strain that flocculates appropriate to the beer you’re brewing.
Alcohol tolerance is the amount of alcohol a yeast strain is able to handle before it stops working. In the past few decades, brewers have been conditioning different yeast strains to deal with a whole range of situations. And clearly, yeast strains now used to make high-alcohol beers have stood up to the challenge. Regardless of how much alcohol you want to put in your beer, pick a strain that can stand it.
Range of Temperature
As a yeast strain performance indicator, temperature range is none other than the temperature zone in which the yeast to works best. Most, if not all, yeasts ferment in temperatures higher than their limits, but the results will be hardly the same for each one. Thus, you need to know the best temperature range for your selected strain, and there are two reasons for this: so you can use the right equipment (some equipment only work at certain temperatures) and to let you adjust the temperature according to your desired flavor profile.
Lasty, while the first four indicators we have mentioned are all measurable, sensory profile is subjective. It all depends on the person that “senses” the brew. In other words, you have to brew a certain yeast strain if you want to get its sensory profile.