65. A holistic examination of beer bitterness

Christina Hahn (1), Scott Lafontaine (1), Thomas Shellhammer (1); (1) Oregon State University, Corvallis, OR, U.S.A.

Technical Session 19: Beer Bitterness
Wednesday, August 17  •  8:15–9:30 a.m.
Tower Building, Second Level, Grand Ballroom

While iso-alpha-acids are the main contributors to beer bitterness, many additional components can add bitterness. Polyphenols and oxidized hop acids can impart bitterness but to varying degrees. Alpha-acid at the levels found in beer do not contribute bitterness, but they can influence the spectrophotometrically measured bitterness unit (BU). Previous research has shown that current industry methods for measuring beer bitterness such as the BU method and direct measurement of iso-alpha-acids via HPLC do not accurately predict the sensory bitterness of a beer over 40 BUs, particularly in beers that have been dry-hopped or heavily late-hopped. This study examined 120 commercial beers using a combination of sensory and instrumental techniques. Chemical analysis consisted of the bitterness unit, 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 with a 19-member trained sensory panel, and the overall bitterness intensity of the beers was rated using a 0 to 20 scale. This study confirmed the inadequacy of total iso-alpha-acids content as a complete measure of beer bitterness. It also resulted in a proposed new model that is an improvement on the traditional bitterness unit for assessing total bitterness using all of the bitter compounds found in beer.

Christina Hahn is a graduate student at Oregon State University (OSU) pursuing a master’s degree in food science and technology as a member of Dr. Thomas Shellhammer’s laboratory. Her research focuses on the sensory perception of beer flavor and its components. Christina received her B.S. degree from OSU in 2015, and during her time as an undergraduate student, worked as lead brewer for OSU’s pilot research brewery. In addition to brewing at OSU, she has interned with Boston Beer Company and Deschutes Brewery.