Fast Screening Method to Determine Hop's Phytoestrogens in Beer

Abstract

A novel, fast, and simple method to determine three phytoestrogens [xanthohumol (XN), isoxanthohumol (IXN), and 8-prenylnaringenin (8PN)] in beer samples by high-performance liquid chromatography with diode-array detection has been developed. The selected method involves purification by solid phase extraction and separation achieved on a C18 column by using a gradient elution program. This consists of a mixture of acetonitrile, water, and methanol (all of them with 1% of acetic acid) at a flow ratio of 1 mL/min. The detection wavelengths were set at 370 nm for XN and 280 nm for IXN and 8PN. Average analyte recoveries were higher than 75% with relative standard deviations lower than 5%. The detection limits were between 0.01 and 0.08 mg/L, and the quantitation limits were between 0.02 and 0.15 mg/L. The method has been validated and applied to the analysis of several types of commercial beers obtained from local markets, where results showed the presence of IXN and 8PN in most of the samples and the absence of XN. Thus, the presented method gives to brewing chemists a validated, reliable, fast, and affordable analytical tool to identify and quantify the three most important hop's prenylflavonoids in beer. © 2010 Springer Science+Business Media, LLC.