Bitter truth: we do not make beer. Even the folks who brew our favorite world-class beers are not truly ‘making’ beer. They are janitors. They are cooks. They are biologists. But they do not make beer. The true hero in the beer making process is the yeast. Yeast is singularly responsible for producing more than ninety flavor and aroma compounds in beer, as well as all of the alcohol present in a finished beer. For a single-celled organism, yeast is a busy creature. Because it’s got such a job to do, we as ‘brewers’ need to do all we can to support it.
There are more than 1500 known strains of ale yeast, and many scientists estimate we have discovered only five percent of the total number of strains in existence. Each of these strains demonstrates different characteristics including attenuation (how much sugar it can convert to alcohol), flocculation (how it clumps up and drops out of solution), alcohol tolerance, and flavor and aroma production. All these different characteristics mean that different strains require (slightly) different treatment and conditions to best do their job. A well constructed recipe takes care of most of the nutritional needs for yeast, but there are a few variables we can control to ensure a clean and consistent fermentation.
Aeration or oxygenation of wort just prior to pitching your yeast is an often overlooked step in home brewing. At any other time in the brewing process, contact with air and oxygen is to be avoided because it can cause stale/cardboardy flavors to develop. However, yeast needs some oxygen early in the fermentation process so it can build healthy cell walls and generate some sterols and fatty acids necessary for the rest of the ferment. Aeration of your wort can be as simple as giving your carboy or bucket a vigorous 1-2 minute shake prior to yeast pitching, or as complex as a pure oxygen bottle and an inline aeration stone. Your method du jour depends on your setup, the beer you’re making, and how much time/money/energy you have. Fun fact: dry yeast needs to be rehydrated prior to use, but does not require aeration. It’s already ready already.
As we discussed in an earlier broadcast, another major variable we, as brewers, can control to ensure a healthy fermentation is temperature. During the fermentation, yeast does its best work under optimal conditions; it doesn’t like stress. Higher temperatures essentially cause the yeast to sweat out various undesirable compounds. Sweat and beer don’t go well together. Don’t stress your yeast: cool your wort!
Remember that happy yeast makes better beer. Do what you can to provide the proper conditions and your yeast will reward you with delicious malty goodness. Neither of these changes to your fermentation process requires large amounts of money or time, but both of them will significantly improve your beer.
The weather is steadily getting colder and brewing is a great way to stay warm. Pick a nice recipe and cuddle up with several billion tiny friends and a few big ones, too. Share the beer! Don’t stress the yeast! As always, give us a call, an email, or drop by the shop if you’ve got any questions about yeast or any other brewing topics.