4. Evaluating hop chemistry and its contribution to hop aroma intensity in dry-hopped beer

Lafontaine, S.1 and Shellhammer, T. H.1, (1)Oregon State University, Corvallis, OR, USA

Technical Session 9: Hops II
Wednesday, June 07, 2017
10:15–11:30 a.m.
Harbourview (1st Floor)

Many factors upstream of the brewery, such as raw material attributes (i.e., total oil content and composition) and processing factors (i.e., harvest maturity), influence hop aroma performance in beer. To investigate the influence of these factors on the dry-hop aroma intensity of multiple cultivars, 63 unique dry-hopped beers were prepared using different lots of Cascade from the 2014 and 2015 harvests, and 12 dry-hopped beers were prepared for both Centennial and Chinook using samples collected from the 2015 harvest. We confirmed that total oil content was not a strong predictor of overall hop aroma intensity (OHAI) in dry-hopped beer for Cascade (R2 = 0.20 for 2015 harvest samples) and similarly for Chinook (R2 = 0.01). However, there seemed to be a suggestive relationship between total oil content and OHAI for Centennial (R2 = 0.38). Much more significant positive correlations were observed between the hop oil analyte concentrations (most notably linalool, geranial, rho cymene, geranyl acetate, and geraniol) with OHAI for the 2015 harvest Cascade samples. In contrast, the 2014 harvest Cascade samples yielded negative correlations for linalool and geranial with OHAI. Significant farm and harvest maturity effects were also observed in the Cascade samples between the two harvest years, with higher oil and later harvested hops showing a higher aroma potential at one farm over the two years. Yet, this same observation was contradicted in other farms and years. Turning to the Centennial and Chinook cultivars, it was interesting to observe a significant positive correlation between myrcene and OHAI for Centennial (R2 = 0.76). In contrast to Cascade, this indicates that myrcene along with other hop oil analytes (specifically, limonene and alpha+beta pinene) may be markers for Centennial dry-hop aroma intensity. For Chinook, linalool and rho cymene appear to be potential positive candidates for aroma intensity, while geranial, trans-farnesol, caryophyllene, alpha-humulene, and E-B-damascenone were negatively correlated to Chinook aroma intensity. This information provides a greater understanding about which hop oil analytes correlate with OHAI in dry-hopped beer. Ultimately, we believe that this information is going to help the industry best designate hops for aroma purposes and understand the variation that exists within and between cultivars.

Scott Lafontaine is a graduate research assistant at Oregon State University and a member of Dr. Thomas Shellhammer’s laboratory. His research focuses on determining factors in hops that drive their dry-hop aroma performance in beer. He assists in the teaching of residential and continuing brewing analytical and quality education courses at OSU. Prior to joining the Shellhammer team at OSU, he received his M.S. degree in Chemistry at OSU in 2015, during which his studies focused on analytical environmental chemistry.