VIEW ARTICLE    DOI: 10.1094/ASBCJ-45-0061

Simultaneous Analysis of Hop Bittering Components by High-Performance Liquid Chromatography. II. Evaluation of Hop Deterioration. M. Ono, Y. Kakudo, R. Yamamoto, K. Nagami, and J. Kumada, Research Center of Suntory, Ltd., Shimamoto, Osaka 618, Japan. J. Am. Soc. Brew. Chem. 45:0061, 1987.

A rapid high-performance liquid chromatography (HPLC) procedure for simultaneous separation and quantitation of the main nine hop bittering components, i.e., three analogs of iso- α-, α-, and β-acids in hops and beer, has also been successfully applied to determine the relative amounts of some components formed during hop storage. These components were eluted in fractions that we designated "S-fractions" in the HPLC profile. When hop pellets were stored in the presence or absence of air at various temperatures from -5 to 50° C, a linear correlation between the increase in S-fractions and the decrease in α- and β-acids was obtained. Based on this correlation, we can estimate from the amount of S-fractions in hops not only the losses of α- and β-acids during storage, but also the initial level of α- and β-acids in hops. The ultraviolet spectrum of each peak in the eluant during HPLC analysis suggests that the major components of S-fractions are tricyclodehydroisohumulones, hulupones, or humulinic acids. Thus, these components were considered to be formed at the expense of α- and β-acids during storage. From brewing trials with strongly deteriorated hops, the bittering and aromatic effects of S-fractions on beer quality were demonstrated by chemical and sensory analyses.

Keywords: α-Acids, β-Acids, Hop deterioration, Hop storage index, Iso- α-acids