Hops have long been used in the brewing of beer and are a resource of particular importance to the Rocky Mountain region. Hops play several vital roles in the brewing process, such as contributing to the bitterness of beer. The bitterness from hops is largely due to the formation of iso-alpha acids in boiling wort. While iso-alpha acids impart desirable flavors in a finished beer, it is also known that iso-alpha acids degrade due to light exposure to produce unfavorable components. In addition, iso-alpha acids thermally decompose over time. As a result, our research group has been studying the thermal degradation of iso-alpha acids to better understand the decomposition chemistry. Employing HPLC and using 4-<i>tert</i>-butylphenol as an internal standard, our group has been able to monitor the concentration of iso-alpha acids as a function of time and temperature. Thus far, the reaction is best modeled by first order reaction kinetics and rate constants for this reaction have been measured at several temperatures. Subsequently, the activation energy has been determined using the Arrhenius equation. Information gathered from this research will give valuable insight into the ever-changing chemical composition of an aging beer.<br/>

Analyzing thermal degradation of iso-alpha acids by high performance liquid chromatography (HPLC)

249th National Meeting (2015)

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