Answer is: a product of a fermentation reaction is ethanol (C₂H₅OH). Fermentation is a metabolic process in which ethanol is produced from sugar in the absence of oxygen (anaerobic digestion)<span>. </span>Fermentation <span>occurs in </span>yeast, bacteria and in oxygen-starved muscle cells. Fermentation is a way of extracting energy from molecules and it is <span>the oldest metabolic pathway.</span>
