A simple assay to screen brewing yeast for the release of proteases into beer is outlined and the impact of the yeast proteases on beer foam stability is discussed.

The established technique of time-resolved fluorescent spectroscopy has been applied to the rapid measurement of beer bitterness. This novel application utilises the unique long-lived fluorescence properties of the lanthanide, europium. Europium ions have the ability to selectively chelate fltricarbonyl structures such as the feo-humulones. The resultant complex is measured by irradiating the sample at a specific wavelength and measuring the intensity of the long-lived emission. The bitterness method measures the total contribution of /so-alpha acids and related congeners. A linear relationship between standard /so-alpha acids solutions and emission intensity was found. However, in beer the effects of colour and other interfering compounds were significant. Decolourization of the beer did not improve the correlation with BU. This paper presents a preliminary investigation into the potential applications of this novel method.

A rapid photo-isomerisation method is described for the production of photo-isohumulone. The use of photo-isohumuione as an ultra-pure standard for the HPLC analysis of iso-alpha acids is described.

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Six identical gas chromatographic (GC) systems from the same manufacturer were evaluated for the determination of ethanol in beers. Each system was assessed for detector linearity and drift using standard ethanol solutions. Repeatability (rss) of each machine, repeatability (rss) of the GC method and reproducibility (Rss) of the method over a range of ethanol concentrations (1-11% V/V) was determined using commercial beers. All six instruments were linear over the ethanol range 0-12% V/V and were in good agreement. Drift of the machines was negligible over the period of the analysis. Over the ethanol range 0.95 to 6.32% V/V the repeatability (res) and reproducibility (Rss) values were 0.050 and 0.083 respectively. Over the ethanol range 9.48 to 11.15% V/V the repeatability (rss) and reproducibility (Rss) values were 0.153 and 0.227 respectively. Comparison of the precision values and those obtained in a recent IOB Analysis Committee Collaborative1 for the determination of ethanol by gas chromatography showed no significant differences between the two methods. The reported method is suitable for determination of ethanol in beers.