A Novel Method for Bitterness Determination in Beer Using a Delayed Fluorescence Technique

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 β-tricarbonyl structures such as the iso-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 iso-alpha acids and related congeners. A linear relationship between standard iso-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.