Determination of Selected Beer Flavours: Comparison of a Stir Bar Sorptive Extraction and a Steam Distillation Procedure

J. Inst. Brew. 117(4), 617-621, 2011 The aim of this work was focused on the comparison of two sample preparation procedures a stir bar sorptive extraction (SBSE) followed by solvent back extraction and a well-established distillation method followed by liquid/liquid extraction for the simultaneous determination of some beer esters (isoamyl acetate, ethyl caproate, ethyl caprylate, ethyl caprate, phenylethyl acetate, ethyl laurate, ethyl myristate, ethyl palmitate) and free fatty acids (caproic, caprylic, pelargonic, capric). Subsequent gas chromatographic analyses with flame ionization detection were used for the determination of these compounds. Both procedures were characterized by good linearity (correlation coefficients were higher than 0.9987). The relative standard deviations were found to be 2.1-7.3% for SBSE and 10-14% for the distillation technique with recovery 81-107% and 70-89%, respectively. Results obtained by these two procedures were in good correlation.