The Production of Isoamyl Acetate
from Amyl Alcohol by Saccharomyces cerevisiae
M. G. Quilter 1, J. C. Hurley 2, F. J. Lynch 2 and M. G. Murphy 1, 3
1Department of Applied Biology and Chemistry, Institute of Technology Carlow, Kilkenny Road, Carlow, Ireland.
2Guinness Research Centre, St. James’s Gate, Dublin 8, Ireland.
3Corresponding author. E-mail: ger.murphy@itcarlow.ie
J. Inst. Brew. 109(1), 34-40, 2003 | VIEW ARTICLE
ABSTRACT
Isoamyl acetate is a natural flavour ester, widely used as a source of banana flavour by the food industry. Fusel alcohols such as amyl alcohol are produced in significant quantities as a waste product, sometimes referred to as "lees oil" or "fusel oil", of the alcohol distilling industry. By manipulation of brewing yeast fermentation conditions, a significant portion of added amyl alcohol was shown to be converted to isoamyl acetate. This was achieved by the addition of L-leucine and amyl alcohol in fermentations carried out by a high ester-producing brewing yeast strain of Saccharomyces cerevisiae and by the use of alkaline fermentation conditions coupled with high gravity media. Mutant strains selected on 5,5,5 trifluoro-DL-leucine produced substantially high levels of isoamyl acetate. The adjustment of fermentation conditions outlined in this paper may act as a stepping stone for the potential use of Saccharomyces cerevisiae and other yeasts to produce high levels of natural flavour esters.
Key words:
Fermentation, headspace-gas chromatography, isoamyl acetate, lees oil, fusel oil, molasses, Saccharomyces cerevisiae
Publication no. G-2003-0304-130 ©2003 The Institute & Guild of Brewing