QUANTITATIVE DETERMINATION OF ESTERS IN BEER BY GAS CHROMATOGRAPHIC ANALYSIS OF HEAD SPACE VAPOURS

The concentrations of ethyl acetate, isoamyl acetate, ethyl caproate, ethyl caprylate and phenethyl acetate have been determined at weekly intervals during the lagering period, after pasteurization for a young beer processed in the normal fashion, and also for the same beer filtered before lagering. The analyses were made directly on the beer without previous isolation or concentration steps, by using techniques for the quantitative analysis of head-space vapour samples on the gas chromatograph. During the lagering of the beer under normal conditions the concentrations of ethyl acetate, isoamyl acetate and ethyl caprylate increased significantly, but the amounts of ethyl caproate and phenethyl acetate did not change. None of the esters showed any significant change in concentration during lagering of the beer which had been previously filtered. Analyses of the normal beer after filtration and bottling and after pasteurization showed no changes in concentration for any of the five esters at either of these stages in the processing.