Humulone, the α-acid found in hops, undergoes a ring contraction during the beer-making process. This mechanism has been evaluated in samples of wort and determined to follow first-order kinetics to provide a mixture of two diastereomers. Interestingly, the reaction proceeds only to about 40% completion at 100°C in one hour. Extended times during the brewing process do little to improve the yield of the reaction. While most of the studies on the mechanism completed to date have been evaluated in wort by HPLC, evalution of the reaction by polarimetry provides utility by varying the key features of the reaction. Our analysis of the reaction indicates that the reaction is highly dependent upon the presence of water, metal cations, and temperature. The results of these evaluations and implications for the mechanism will be presented.

Kinetic studies on the isomerization of humulone

251st National Meeting (2016)

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