Question

What is the other product of the fermentation of a sugar, aside from ethanol?

Answer 1

Carbon dioxide.

Explanation:

It is the carbon dioxide that gives natural beer its foamy 'head' and tingling oral sensation. It is lost/removed when using the alcohol mash to distill "spirits" like whiskey.

Also, left to oxidize further, the ethanol will turn into acetic acid (vinegar).

Water is also produced, but is negligible to the water solution in which the fermentation usually is taking place.