An improved ethanol fermentation process with decreased use of acidifiers by adding a composition containing an aldehyde, a fatty acid, a terpene and a surfactant. The method comprising:a) mixing a fermentation feedstock with a fermentation broth containing yeast and/or an enzyme,b) treating said mixture by adding a composition to the fermentor containing:10 - 90 wt. % of an antimicrobial aldehyde, preferably selected from the group consisting of formaldehyde, para-formaldehyde, glutaraldehyde, and mixtures thereof,1- 50 wt. % of a surfactant having an HLB from 4 to 18,0 - 20 wt. % of an antimicrobial terpene, or essential oils,1- 50 wt. % of organic acids selected from C1 to C24 fatty acids, their salts, glycerides and esters thereof, and1- 50 wt. % waterwherein the concentration of aldehyde in the fermentor is from about 0.25 to 3 kg/MT of fermentation feedstock, andc) isolating ethanol and improving yield.
