Formation Of Acetate Esters Research Articles

Ester Formation by Alcohol Acetyltransferase from Brewers’ Yeast

Alcohol acetyltransferase responsible for the formation of acetate esters during beer fermentation was found to be localized at the cell membrane of brewers’ yeast. This cell membrane-bound enzyme was purified 120-fold by solubilization with Triton X-100, gel filtration on a Sepharose 6B column and chromatography on a DEAE-Sephadex A-50 column. The enzyme was most active at 30°C at pH 7 ˜ 8. It was least active against C3 alcohol among C1 ˜ C6 alcohols, and slightly more active against straight-chain alcohols than against branched-chain alcohols with the same carbon number. The enzyme was strongly inhibited by unsaturated fatty acids, heavy metal ions and sulfhydryl reagents.

Ester formation by alcohol acetyltransferase from brewers' yeast.

Alcohol acetyltransferase responsible for the formation of acetate esters during beer fermentation was found to be localized at the cell membrane of brewers' yeast. This cell membrane-bound enzyme was purified 120-fold by solubilization with Triton X-100, gel filtration on a Sepharose 6B column and chromatography on a DEAE-Sephadex A-50 column. The enzyme was most active at 30°C at pH 78. It was least active against C3 alcohol among C1C6 alcohols, and slightly more active against straight-chain alcohols than against branched-chain alcohols with the same carbon number. The enzyme was strongly inhibited by unsaturated fatty acids, heavy metal ions and sulfhydryl reagents.

Variations in Some Volatile Acetate Esters Formed during Grape Juice Fermentation. Effects of Fermentation Temperature, SO2, Yeast Strain, and Grape Variety

Some of the factors affecting volatile acetate ester formation in wine fermentation were studied. The temperatures of fermentation that gave maximum formation were found to be 60-70°F for ethyl acetate, n-propyl acetate, and isoamyl acetate, and 50-60°F for isobutyl acetate. Ester formation also was influenced greatly by temperature, and yeast strain contributed to differences in the amounts formed. Sulfur dioxide content had an effect and interacted with temperature in certain cases to cause variation in ester content. The substrate also affected the amount of volatile acetate esters formed.