Speed of fermentation

Is mead better when fermentation is slower? Or is mead better when fermentation is faster? Some people, in the name of tradition, answer that fermentation must take time, whereas some other people prefer a faster fermentation. Whichever prejudice one has, it should be admitted that trying and answering this question using reasons other than "in the good old days..." or "I am in a hurry" would be better. The final result must be the only judge.

• A low temperature (do not exaggerate) will slow down the fermentation but it will also modify the balance between chemical reactions and the proportions of various products (and therefore the taste).
• Agitation scatters yeast cells, so they are more efficient (ferment faster). But this also drives off some volatile organoleptic compounds one may prefer to keep in the mead [V2].
• Some strains of yeast are intrinsically faster than others. But differences in the final result will depend more on other differences between yeasts than on the difference of fermentation speed.
• If fermentation lasts too long, autolysis can take place and modify the taste.
• If fermentation lasts too long, the must will also spend some time containing some sugar and little alcohol, which is a perfect environment for the development of bacteria.
• Slowness of fermentation can also be a sign of bad health of the yeast or of some handling mistake (see stuck fermentation in A problem?). In such a case slowness is a bad sign.
• On the other hand, if fermentation is made faster by adding excessive nutrients, mead will need a long ageing time to get rid of the nutrient off-flavor. The few days of fermentation time spared this way will be reimbursed later at a credit card rate.

One can therefore notice that there is a link between speed of fermentation and quality of mead. But no over-simplification. In order to say whether slow or fast fermentations are better, it is necessary to know the cause of such a speed. Generally speaking, the speed itself is less important than some cause that will modify both the speed and the quality.