Iso-α-acids Degradation in Beer

Iso-a-acids are one of the key components that provide bitterness to beer. Understanding the stability of beer flavor over extended period is useful to the rapidly expanding craft beer industry and to the consumer. The lupulin glands of hops (Humulus Lupulus, L.) contain three a-acids: humulone, adhumulone, and cohumulone. The a-acids are converted to six iso-a-acids upon boiling, this is the main reason for boiling wort during the brewing process. The six iso-a-acids are cis­-isohumulone, trans-isohumulone, cis-isoadhumulone, trans-isoadhumulone, cis-isocohumulone, and trans-isocohumulone. We propose that the concentration of iso-a-acids in beer will decline over time based on observation that freshly brewed beer has much stronger flavor compared to an older batch. Sufficient beer samples from a single batch shall be obtained from a local brewer, Apocalypse Ale Works, LLC, located in Forest, Virginia. High Performance Liquid Chromatography (HPLC) and International Calibration Extract-3 (ICE-3) will be used to quantitatively determine the concentrations of iso-a- acids in beer samples. Beer samples will be analyzed every two weeks. This study will span for the duration of one year. The rate of loss of iso-a-acids by degradation shall be reported upon the conclusion of this study