A fruity or estery aroma is a byproduct of fermentation which is more pronounced at warmer fermentation temperatures. Some fruityness is acceptable in certain styles of ales. The strain, as well as the quantity, of yeast often determines the degree of fruitiness that is imparted to the beer. The fermentation of cane or corn sugar may also contribute to the degree of fruitiness. Beer styles with higher alcohol content also exhibit fruity esters.
Any one or more of the following may reduce the amount of fruitiness:
Ferment at a lower temperature.
Change yeast type.
Reduce or eliminate the use of corn sugar (substitute malt extract).