Fatty Acid Profiles of Some Cultured and Wild Yeasts in Brewery. Ernest C.-H. Chen, Research and Development Department, Molson Breweries of Canada Ltd., Montreal Quebec H2L 2R5. J. Am. Soc. Brew. Chem. 39:0117, 1981.

A simple, rapid, microscale, gas chromatographic method was developed for the determination of fatty acids in yeast. The method includes a simplified procedure for extraction and saponification, the use of a direct pyrolytic methylation technique, and the use of a high resolution wall-coated open tubular column. A total of 19 strains of cultured, wild, and alcohol-tolerant yeasts previously grown in brewer's wort at 20° C were analyzed. Chromatographic and quantitative profiles for each strain of yeast were established. Apart from some subtle differences among the yeasts, three major distinctions were apparent: 1) Cultured yeasts contained more saturated fatty acids, among which palmitic acid was the most abundant. On the other hand, wild and alcohol-tolerant yeasts contained more unsaturated fatty acids, among which palmitoleic acid was usually the most abundant. 2) The ratio of stearic to oleic acid was greater than 1 for cultured yeasts but smaller than 1 for the other yeasts. 3) Some additional fatty acids hitherto unidentified were present in most of the wild and alcohol-tolerant yeasts. Differentiating or identifying brewery yeasts by analyzing their fatty acid composition would therefore appear possible.

Keywords: Cultured and wild yeasts, Fatty acid profile, High resolution gas chromatography, Pyrolytic methylation, Yeast differentiation