An improved HPLC method for single-run analysis of the spectrum of hop bittering compounds usually encountered in beers: Simultaneous HPLC determination of hop bitter acids

Oladokun, Olayide; Smart, Katherine; Cook, David

Abstract

A single‐run reverse phase‐high performance liquid chromatography method for the quantification of humulinones, α‐acids, iso‐α‐acids and reduced iso‐α‐acids (where present) in commercial beer samples is presented. The method utilizes a binary solvent system consisting of (A) 1% v/v acetic acid and (B) 0.1% v/v orthophosphoric acid in acetonitrile. Separation was achieved on a Purospher® star RP‐18 column (250 × 46 mm, 3 µm) with a flow rate of 0.5 mL/min. The compounds of interest eluted within 32 min. The method was fully validated according to International Conference on Harmonization guidelines and subsequently applied to monitor degradation of hop acids in a storage trial where four lager beers were aged at 28 and 38 °C for 70 and 60 days, respectively. Results confirmed the widely reported degradation through storage of trans‐iso‐α‐acids whilst demonstrating that the HLPC method was sufficiently sensitive to monitor and model this degradation. One beer exhibited a significantly lower (P [less than] 0.05) rate of trans‐iso‐α‐acid degradation than the other conventionally hopped beers in the study, which might have been linked to its higher pH (4.71 vs 4.36). The relative stability of reduced iso‐α‐acids during ageing was also confirmed.

Citation

Oladokun, O., Smart, K., & Cook, D. (2016). An improved HPLC method for single-run analysis of the spectrum of hop bittering compounds usually encountered in beers: Simultaneous HPLC determination of hop bitter acids. Journal of the Institute of Brewing, 122(1), 11-20. https://doi.org/10.1002/jib.299

• Journal Article Type: Article
• Acceptance Date: Oct 28, 2015
• Online Publication Date: Jan 25, 2016
• Publication Date: 2016-02
• Deposit Date: Jan 21, 2020
• Journal: Journal of the Institute of Brewing
• Publisher: Wiley
• Peer Reviewed: Peer Reviewed
• Volume: 122
• Issue: 1
• Pages: 11-20
• DOI: https://doi.org/10.1002/jib.299
• Public URL: https://nottingham-repository.worktribe.com/output/1867497