The first books I read on homebrewing all talked about the dangers of autolysis. I have only experienced it in several meads that I made with wine yeast and that was after two or three years in the *primary* fermenter on the entire yeast cake. Were these early homebrewing books overemphasizing the likelihood of off aromas (rubbery, etc.) and flavours from autolysis, or was it a bigger problem with yeasts that were of questionable viability and probably stored, unrefridgerated, for months?

-Al

RESPONSE:

Autolysis is always something that you have to consider if you leave mead on the yeast after all of the sugar has been converted to alcohol. Many of the yeast have already died by the end of the fermentation and the remainder will die soon, rubbery. Within a few weeks most of the yeast will died and begin to autolyze. The right amount of autolysis produces a nice nutty character to the mead. You need to get the right balance of autolysis.

If your mead fermentation takes many months for completion you will run into the possibility of producing off flavors and aromas. Extended fermentation time indicates unhealthy yeast that can produce skunky off flavors and aromas. Unhealthy yeast comes from lack of nutrients and oxygen earlier in the fermentation. Honey contains very little nutrients for yeast growth. You will need to supplement with a well balanced nutrient such as Fermaid K. Honey also contains very little if any buffering material. The pH will drop dramatically during the first few hours of fermentation, sometimes to as low as 2.7 -2.9. This will seriously stress the yeast, producing a very unhealthy yeast cell resulting in a long drawn out fermentation. This problem can be minimized by adding a small amount of potassium carbonate at the beginning of the fermentation. You should strive for the fermentation to be completed in one to two weeks.

If you want a light, fruity mead, you will need to settle, rack and filter ASAP. If you want to age the mead on the lees or yeast then you should allow to settle lightly to get rid of some of the yeast. Rack while still cloudy to have some yeast left. This yeast will autolyse. Stir weekly until you have achieved the amount of nutty toasty character that you desire. This can range from a couple of weeks to several months. Stirring speeds up the release of the autolyzed amino acids from the yeast cell. Champagne houses leave the champagne on the yeast for three or more years to get the full yeasty, nutty, toasty effect. They cannot stir to speed up the reaction.

Dr. Clayton Cone