Kvasny Prum. 2011; 57(7-8): 296-304 | DOI: 10.18832/kp2011035

Investigation of Czech hop varieties authenticity by means of chemical and genetic analyses.Peer-reviewed article

Karel KROFTA, Josef PATZAK

Chmelařský institut s. r. o., Žatec, Kadaňská 2525, 438 46 Žatec

Autenticity of the current file of eleven Czech hop varieties was elaborated on the basis of analyses of alpha acids, beta acids, hop oils and prenylated flavonoids. Varietal discrimination was based on cohumulone ratio, contents of selected aliphatic esters and sesquiterpenes farnesene and selinenes in hop oils and content of xanthohumol, desmethylxanthohumol and xanthohumol/alpha acids ratio. Identification scheme was constructed with the help of these descriptors. Analyses of dried hops by molecular-genetic methods proved that identification of hop varieties is feasible from this material. Reliability of hop varieties identification generally depends on age of samples and on the way of raw hops processing to hop products. DNA analyses are not practicable in hop extracts and are limited in hop pellets due to DNA fractionation or destruction under processing conditions. Model tests of Saaz aroma variety adulteration with the help of chemical and geonome analyses identically showed that the lowest level of conclusiveness is at about of 10 % admixture. Recently discovered real incident of Saaz hops adulteration showed that proportion of unknown variety was in the interval of 50-70 %.Autenticity of the current file of eleven Czech hop varieties was elaborated on the basis of analyses of alpha acids, beta acids, hop oils and prenylated flavonoids. Varietal discrimination was based on cohumulone ratio, contents of selected aliphatic esters and sesquiterpenes farnesene and selinenes in hop oils and content of xanthohumol, desmethylxanthohumol and xanthohumol/alpha acids ratio. Identification scheme was constructed with the help of these descriptors. Analyses of dried hops by molecular-genetic methods proved that identification of hop varieties is feasible from this material. Reliability of hop varieties identification generally depends on age of samples and on the way of raw hops processing to hop products. DNA analyses are not practicable in hop extracts and are limited in hop pellets due to DNA fractionation or destruction under processing conditions. Model tests of Saaz aroma variety adulteration with the help of chemical and geonome analyses identically showed that the lowest level of conclusiveness is at about of 10 % admixture. Recently discovered real incident of Saaz hops adulteration showed that proportion of unknown variety was in the interval of 50-70 %.

Keywords: alpha and beta acids, hop oils, farnesene, DNA, hops adulteration

Received: June 19, 2011; Accepted: July 27, 2011; Published: July 1, 2011