Effects of Fermentation Environment on Yeast Lipid Synthesis. E. Pfisterer, I. Hancock, and I. Garrison, Labatt Breweries of Canada Ltd., London, Ontario, Canada N6A 4M3. J. Am. Soc. Brew. Chem. 35:0049, 1977.

The goal of the present investigation was to study the influence of various brewing parameters on the total lipid content as well as the fatty acid composition of the yeast. The effects of fermentation temperature, aerobic vs. anaerobic growth, yeast strain, and adjunct level were explored. The results revealed that yeast contained more lipids and more unsaturated fatty acids when grown at lower temperatures. Aerobic growth conditions increased the amount of unsaturated acids and sterols. The fatty acid composition of three yeast strains displayed some differences when grown under identical conditions and the total lipid content rose markedly when increasing portions of corn syrup were used for wort production. In an effort to determine the site of these lipid changes, yeast cells were homogenized and subjected to a differential centrifugation. Three different subcellular particles were obtained and analyzed for lipids. An attempt was made to correlate some of these findings with the accumulation of ethyl acetate in the resultant beer.

Keywords: Adjunct, Ethyl acetate, High-gravity brewing, Lipids, Yeast.