Mead Fermentation and Yeast
A very important part of learning how to make mead is to know what yeast to select to create a good vigorous fermentation in your honey water must.
Mead often has somewhat high starting gravity and a higher alcohol content than wines for example unless making a stronger wine. The most common yeasts used in mead fermentation are the stronger wine yeasts with higher alcohol tolerances. Common yeasts used in the recipes here are Lalvin D-47, Lalvin EC-1118, and Cotes de Blanc (Redstar), but make your own analysis based on the type of mead being made.
In most of the recipes listed here, a yeast nutrient and energizer is used to help get the yeast the starting base it needs for a strong fermentation. In addition to that, or in place of it, many will also recommend a yeast “starter” which is a small batch of the yeast that is activated prior to putting it into the must. The idea is to get the best fermentation and yeast growth possible.
Yeast are the engine that converts the sweet honey water mixture into the delicious elixir that is honey wine mead. The yeast will grow, and as they grow consume the sugar in the must to fuel the growth. A byproduct of this growth process is alcohol (this is fermentation). Also given off is C02 which is what makes the airlock bubble in a fermenting batch of mead. This is also why there must be an airlock or otherwise open release valve for the gas to escape or your fermentation container will explode.
Once the yeast have either converted all the sugar to alcohol (and resulting in a dryer mead) or reached their alcohol tolerance, then they die and sink to the bottom of your mead to be cleared by racking.
Knowing the starting gravity of your must and the alcohol tolerance of the yeast is important when trying to determine the final alcohol content and the final sweetness or dryness of the finished mead. For example, if the gravity is too high and/or the yeast’s alcohol tolerance is too low then a mead that may have been planned to be a dry mead will be a sweeter mead. Or the same thing can happen in reverse and a low starting gravity and/or a high alcohol tolerant yeast will change a planned sweet mead into a dry mead.