Subject: During the fermentation of sugars, what reactions form acids??

During the fermentation of sugars (specifically glusoce, fructose and sucrose) 
by brewer's yeast to produce alcohol and CO2, what reactions form acids?? are 
acids produced at all, assuming it is in an anaerobic environment??  Would 
only the addition of oxygen cause acids to form??

Re: During the fermentation of sugars, what reactions form acids??