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 C 18 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.

Determination of Xanthohumol in Hops, Food Supplements and Beers by HPLC

“…The low LOD and LOQ values of 0.016 mg/L and 0.05 mg/L, respectively, confirm the good sensitivity of the method. These values were better than those described by Dhooghe et al (2010) [13] for hop extracts using HPLC-DAD and were similar to those described by Bernal et al [18], for the analysis of beer samples by HPLC-DAD (LOD 0.01 mg/L). Despite the good results, the values reported in some previous studies were slightly better than those obtained in our study.…”

“…Values between 0.0028 and 0.137 mg/L were reported, and an increase in the concentration of XN during the storage of beer was observed. On the contrary, in the study carried out by Bernal et al (2011) [18] using HPLC-DAD, XN was not detected in the beer samples analyzed. These authors analyzed dark beers, golden/pale beer and non-alcoholic beer, and in all cases the contents were below the limit of detection (0.01 mg/L).…”

Chiral separation of isoxanthohumol and 8‐prenylnaringenin in beer, hop pellets and hops by HPLC with chiral columns

“…In HPLC‐UV–vis methods, the three analytes were monitored by diode array detector. IX and 8‐PN were detected at 280, 290 or 295 nm and XN was detected at 370 or 375 nm (Dhooghe et al, ; Possemiers et al, ; Wunderlich et al, ; Bernal et al, ; Prencipe et al, ), while the three analytes were detected at 295 nm with UV–vis detection in this study. The gradient elution analysis with water–acetonitrile (Dhooghe et al, ; Wunderlich et al, ; Prencipe et al, ), water–methanol (Possemiers et al, ) or water–acetonitrile–methanol (Coldham & Sauer, ) has been reported.…”

“…XN, IX and 8‐PN in beer and/or hop‐related samples have been analyzed by HPLC with UV–vis detection (Dhooghe et al, ; Possemiers et al, ; Wunderlich et al, ; Bernal et al, ; Kao & Wu, ; Prencipe et al, ) and mass spectrometry (Kao & Wu, ; Prencipe et al, ; Stevens et al, 1999a, b; Coldham & Sauer, ; Krause et al, ; Dresel et al, ). Stevens et al () found that, during beer making, XN was largely cyclized to IX and that further losses of XN in beer were due to precipitation, adsorption to insoluble proteins and adsorption to yeast cells during fermentation.…”

Differences in the Levels of the Selected Phytoestrogens and Stable Isotopes in Organic vs. Conventional Hops and Beer

“…Supplementary material-Table S3 gives retention times and MRM parameters. Although several published methods [25,27,28] suggest filtering the samples using nylon filters, we found that these filters adsorbed the compounds of interest and that RC membrane filters were a better option.…”