ANALYSIS OF FREE FATTY-ACIDS, FUSEL ALCOHOLS, AND ESTERS IN BEER - ANALTERNATIVE TO CS2 EXTRACTION

Beer flavor compounds of routine interest were analyzed by gas chromat ography using either direct headspace injection or solvent extraction. The headspace chromatographic method described here makes it possible to analyze dimethyl sulfide, ethyl acetate, propanol, isobutanol, iso amyl acetate, isoamyl and amyl alcohols, and less volatile compounds s uch as ethyl caproate (168-degrees-C) and ethyl caprylate (208-degrees -C) in less than 20 min. Two calibration methods are described: daily calibration or the use of an internal reference beer system, which con siderably simplifies the calibration procedure for long-term use. Alth ough rapid and accurate, headspace analysis discriminates against the less volatile compounds. A complementary chromatographic method, both quick and simple, was designed to assay amounts of caproic, caprylic, and capric acids; beta-phenylethanol; and beta-phenylethylacetate in f ermenting wort and beer. In combination with headspace analysis, this method using hexanol as the extracting solvent yielded beer aroma prof iles similar to those obtained with the carcinogenic solvent CS2. Repe atability of the two solvent extraction procedures was studied by repl icating the analyses. The combined techniques were used to investigate relationships between flavor compounds and their formation in 48 lage r beers.