Chemotaxonomic characterization of hop genotypes based on profiling of proanthocyanidins using liquid chromatography coupled with high-resolution accurate mass spectrometry

Abstract

To determine the varietal specificity of the composition of proanthocyanidins (PACs) in hops, a fast and simple method of liquid chromatography coupled with high-resolution accurate mass spectrometry for qualitative profiling of PACs was developed. A total of 140 samples of 19 hop varieties were analysed. Three (epi)catechin-(epi)afzelechin dimers, six (epi)catechin-(epi)catechin dimers, four (epi)gallocatechin-(epi)gallocatechin dimers, seven (epi) catechin-(epi)gallocatechin dimers, and seven trimers consisting of (epi)catechin building blocks were detected in the hop samples. The cluster analysis of PAC varietal profiles showed their close link with the genetic origin of the hops. The main marker distinguishing the American and European genotypes is the representation of catechin and epicatechin in the PAC profile. The varieties in both of these genotype groups are further subdivided based on their low or high proportion of (epi)gallocatechin building blocks in the PAC profile. Knowledge of the composition of proanthocyanidins in hops can be important for the selection of hop varieties in brewing, pharmacy or food supplement production. The developed PAC profiling method can be easily adapted to other plant materials.