I've read that having a high quantity of honey in the batch will cause the yeast to die at certain alcohol levels and leave unfermented sugar behind. Some of the yeasts designed for sweet mead (like the Wyeast 4184) say they are designed to leave a certain amount of sugars behind no mater the alcohol level.
In a mead, virtually all the sugars are fermentable, so the yeast will ferment all the sugar available until they reach the limit of alcohol they can tolerate. As long as you start with a gravity (or potential alcohol level) higher than the alcohol tolerance of the yeast, you'll end sweet. The problem is that you can't be quite sure what that alcohol tolerance is - the listed numbers are not always what you get in practice so you could be higher or lower depending on the must. That means you won't be certain how sweet you end up. It could be just right, or you could end up with it being syrupy.
One way around this problem is to ferment with a gravity to produce the level of alcohol you want, and then stabilize the mead using sulfite/sorbate to prevent continued fermentation. Then you can sweeten it up to the exact level you want. I often take this approach.
With the Wyeast sweet mead yeast the alcohol tolerance is around 11-12% ABV. As long as you start with a gravity above about 1.090, you'll probably have residual sugar (if it sticks, you definitely will
) With a yeast like 71B, the tolerance is about 14% so you need to start with a gravity above 1.105 to end sweet (give or take).
So, for brewers yeast, I was under the impression that fusels were formed by either high temps, under-pitching and/or insufficient oxygenation. Are these also true for mead (meaning wine/champagne yeast)?
Factors that lead to higher fusels are higher temperature, more oxygenation (not less), higher pH, higher pitch rates (not under-pitching), higher level of solids, and possibly higher levels of precursor amino acids (but this is debated). Bayanus strains may also be more prone to fusel production.
Temp is the most important of these factors, and the production of fusels seems to occur most during times of rapid yeast growth, i.e, during the early part of fermentation. Letting the temp rise late in the fermentation does not seem to cause the same problem.
My apologies to the OP for diverting this thread into a discussion of yeast physiology.
Medsen
seriously though it is a valid point and I might consider starting to use beer bottles myself for the point he made about bringing out various types in one sitting.
