Brewing Education: Yeast, what difference does it make?

In this series of Brewing Education we are going to be going over the differences in the basic ingredients that go into mead. Today we will be focusing on yeast, what it does, and what different kinds there are.

So, what is yeast? Yeast are single-celled microorganisms that are technically classified as a fungus. Yeast are found everywhere and on nearly everything making cultivating wild yeast fairly simple. Yeast is used in many ways, such as making most breads, as well as beers, wines, and mead. There is a difference between what kinds of yeast can be used for what, or to be more accurate what kinds of yeast have been engineered to work best at creating the desired product. You can definitely use wild yeast to make mead, or mead yeast to make bread, however the product would not be nearly as high a quality as what would be produced by using the correct yeast - using the correct tool for the right job.

For mead making we tend to use wine and/or champagne yeast as they have a higher range of alcohol tolerance and a wide range of flavor enhancing byproducts during fermentation. Yeast is the catalyst that turns your honey water into mead by breaking down the sugars in honey and turning it into CO2 gas and alcohol as well as smaller amounts of esters, phenols, and other chemical compounds.

What is alcohol tolerance? One of the most important things to consider when determining what yeast to use is its alcohol tolerance - how much alcohol the yeast can tolerate before they cease turning sugar into alcohol. Specialized yeast are genetically modified to produce up to a certain amount of alcohol and will determine the maximum ABV of your brew. We typically like to use Lalvin 71B wine yeast which has an alcohol tolerance ~ 14% which is a respectable ABV for a mead. Now this number does not mean that you *must* have your final product end with an ABV equal to the yeast's tolerance. You can easily calculate a target initial specific gravity before you start fermentation so that it ends at the ABV you desire; however you will just not be able to go much above the yeast tolerance.

What other aspects of yeast do we consider? Different yeasts have different features you will want to research to determine what is best for your brew, but there are a couple of important ones for determining its suitability for brewing. One is the temperature range the yeast is active. Now most yeast do have a fairly wide range for active temperature. Take for example again the Lalvin 71B which has a range of 59 - 89 F which means you want to keep the brew within that range while you are fermenting it; anything significantly lower or higher than that range will kill the yeast or cause them to go dormant, which means no fermentation. So be sure to choose a yeast with a range you can maintain for months at a time (since the ranges tend to be so large this isn't typically a problem). Also something to look at is the espers a yeast will produce as a byproduct. Again the 71B, for example, enhances fruity flavors and produces fruit espers, which means it is a good yeast if you are making a fruit-based mead, also called a "melomel". Determining what flavors are brought out by a yeast is important for your vision of the final product of your brew, and makes your yeast selection an important decision.

The next installment of the Brewing Education series will feature the importance of honey selection, and the quality of said honey.

Stay safe and remember to love one another!

~ The Forge Meadery