VIEW ARTICLE    DOI: 10.1094/ASBCJ-43-0127

Changes in Hop Oil Content and Hoppiness Potential (Sigma) During Hop Aging. Robert T. Foster, II, Adolph Coors Company, Golden, CO 80401, and Gail B. Nickerson, Department of Agricultural Chemistry, Oregon State University, Corvallis 97331. J. Am. Soc. Brew. Chem. 43:0127, 1985.

This study evaluates the chemical changes in hop oil content and composition during storage of 20 different hop varieties obtained from the hop breeding program at Oregon State University. Chemical analyses of the hop acids and hop oil were performed on mature plants at harvest (fresh) and after a six-month room-temperature stability test (aged). Nineteen main hop compounds for each variety were then calculated to a microliters per kilogram of wort level based on an equal original α-acids hopping rate for comparison. The three groups of hoppy compounds that were derived and totaled were the oxidation products (Σoxp/hp), the floral compounds (Σf/hp), and the citrus compounds (Σc/hp) groups. These three specific hoppiness groups were then totaled, and a total hoppiness potential value (Σtot/hp) called "Sigma" was derived. Using this sigma value, the 20 different hop varieties were put into four hop categories (aroma, bitter, etc.) based on changes in total hoppiness potential with respect to hop aging.

Keywords: α-Acids loss, Hop oil oxidation, Hop varieties, Myrcene loss, Sigma, Total hoppiness potential