Analysis of Selected Esters in Beer: Comparison of Solid-Phase Microextraction and Stir Bar Sorptive Extraction

Tomáš Horák^*, Jiří Čulík, Vladimír Kellner, Marie Jurková, Pavel Čejka, Danuša Hašková and Josef Dvořák
Research Institute of Brewing and Malting PLC, Brewing Institute Prague, Lípová 15, CZ–120 44 Prague 2, Czech Republic.
^*Corresponding author. E-mail: horak@beerresearch.cz.

J. Inst. Brew. 116(1), 81–85, 2010 | VIEW ARTICLE

ABSTRACT
Esters represent one of the most important flavour groups inbeer. The aim of this work was focused on the comparison of two optimized, simple, rapid and low cost methods, the solidphase microextraction technique and the stir bar sorptive extraction technique, for the determination of beer esters, in particular isoamyl acetate, ethyl caproate, ethyl caprylate, ethyl caprate, phenylethyl acetate, ethyl laurate, ethyl myristate, and ethyl palmitate. Subsequent gas chromatographic analyses with flame ionization detection were used for the determination of these compounds. Linearity, recovery, and repeatability of these methods were compared. Working parameters of both procedures were similar and characterized by high repeatability (2.1–7.3%) and good linearity (correlation coefficient ranging from 0.9991 to 0.9999). Results obtained by these two procedures were in good correlation.

Key words:
beer, beer esters, solid-phase microextraction (SPME), solvent back extraction, stir bar sorptive extraction (SBSE)