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摘要
A single-run reverse phase-high performance liquid chromatography method for the quantification of humulinones, alpha-acids, iso-alpha-acids and reduced iso-alpha-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 (R) star RP-18 column (250 x 46mm, 3 mum) with a flow rate of 0.5mL/min. The compounds of interest eluted within 32min. The method was fully validated according to International Conference on Harmonization guidelines and subsequently applied tomonitor degradation of hop acids in a storage trial where four lager beerswere aged at 28 and 38 degrees C for 70 and 60 days, respectively. Results confirmed the widely reported degradation through storage of trans-iso-alpha-acids whilst demonstrating that the HLPC method was sufficiently sensitive to monitor and model this degradation. One beer exhibited a significantly lower (P < 0.05) rate of trans-iso-alpha-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-alpha-acids during ageing was also confirmed.
- 出版日期2016
