Graduate Thesis Or Dissertation
 

A Comprehensive Evaluation of the Nonvolatile Chemistry Affecting the Sensory Bitterness Intensity of Highly Hopped Beers

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  • The range of different nonvolatile constituents extracted from hops in highly hopped beers suggests that iso-alpha acids may not be the sole contributor to beers’ bitterness. Among brewers producing hop-forward beer styles there is a growing concern that the Bitterness Unit (BU) is no longer an accurate predictor of beer bitterness. This thesis presents the results of a research project focused on examining factors within the beer matrix that influence sensory bitterness perception in highly hopped beers. Over 120 commercial beers were evaluated using a combination of sensory and instrumental techniques. Chemical analysis consisted of the BU, hop acids via HPLC, total polyphenols via spectrophotometry, and alcohol content plus real extract via an Alcolyzer (ASBC Beer 23a, 23e, 35, 4g). Sensory analysis was conducted in over two studies with specific objectives for each. A multiple replication study focused on evaluating a small number of beers (30) with a small (10 member) trained sensory panel. Three sensory replications were completed with all 30 beers. A single replication study focused on evaluating a larger number of commercial beers (91) with a larger (19 member) trained sensory panel. One sensory replication was completed with all beers and three replications were completed with two beers serving as internal standards. The beers’ overall bitterness intensity were rated using a 0 to 20 scale. This study revealed the chemical drivers of sensory bitterness, confirmed the inadequacy of total iso-alpha acid content as a complete measure of beer bitterness, and proposed an alternative, liquid chromatography approach to predicting bitterness based on the combination of iso-alpha acids, humulinones, and ethanol concentrations.
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  • Existing Confidentiality Agreement
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  • 2018-01-23 to 2018-05-27

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