Analysis of Hop Acids and Their Oxidized Derivatives and Iso-α-acids in Beer by Capillary Electrophoresis−Electrospray Ionization Mass Spectrometry

This study investigates the applicability of on-line coupling of capillary electrophoresis with electrospray ionization tandem mass spectrometry (CZE-ESI-MS) for the separation and characterization of α ¬and β-acids and oxidized hop acids from crude extracts of different hop varieties. CZE-ESI-MS with negative-ion electrospray ionization proved to be a suitable technique for the determination of these types of natural compounds and their oxidized derivatives. The CZE parameters (pH, concentration, and buffer type) and ESI-MS parameters (nature and flow rate of the sheath liquid, nebulizer pressure, drying gas flow rate, temperature, and compound stability) were optimized. The optimized method provides the potential for a fast qualitative determination of hop acids and their oxidation compounds. The method was also applied to the determination of iso-α-acids in beer

Content of biogenic amines and polyamines in beers from the Czech Republic

Altogether 114 samples of alcoholic and non-alcoholic bottled beer produced in 28 breweries in the Czech Republic were monitored for levels of biogenic amines (BA) and polyamines (PA). The beers were analysed immediately after purchase and then at the end of the best-before period (storage temperature 8 +/- 1 degrees C). The concentrations of histamine, phenylethylamine and tryptamine in the studied samples were very low (mostly under 30 mg L-1). The studied PA spermine and spermidine also occurred in small amounts. Nevertheless, the levels of tyramine, putrescine and cadaverine reached significant values, especially in alcoholic beers. In almost 25% of the tested samples of alcoholic beers (at the end of the best-before period), the total amount of all the monitored BA and PA exceeded the 'healthy' level of 100 mg L-1, which is considered toxicologically significant, especially in alcoholic beverages. Copyright (C) 2012 The Institute of Brewing & Distillin