ESTIMATION OF Α-, Β- AND ISO-α-ACIDS IN HOPS, HOP PRODUCTS AND BEER USING HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

Abstract

Methods are described in which high performance liquid chromatography (HPLC) is used to estimated-, P-and iso-a-acids in hops, hop products and beer. The chromatography relies on an isocratic elution of components from a polythene 'cartridge' column, and the method is calibrated with the pure substances as primary standards. Using such a column over 1000 analyses have been carried out without any signifi cant loss in resolution or precision. The procedures are sufficiently rapid for use in commercial trans actions and for quality control purposes. For hops and hop extracts coefficients of variation (%) of 2-5 and 0-8 were obtained respectively for a-acids. Values of 0-9 and 0-3 were obtained for iso-a-acids in isomerised extracts and beers respectively. For some isomerised extracts it has been observed that peaks in addition to those given by the iso-a-acids are present on the chromatogram. The current method recommended by the EBC over estimates the iso-a-acid content since these other constituents are included in the analysis.

determination of Caffeine and Isohumulones in Saliva by HPLC Analysis

“…During the wort boiling process befor fermentation, alphaacids are transformed into iso-alpha-acids (IAA, more bitter than alpha-acids and the so-called isohumulones, primarily isohumulone, isocohumulone, and isoadhumulone;Palamand and Aldenhoff, 1973) which give beer its characteristically bitter taste. There is little information on the transfer of IAA to humans, compared to organoleptic and chemical work on hop-derived bitterness (Buckee, 1985;Verzele et al, 1981;Saag, 1988; and others). There was no report related to the determination of the salivary level of IAA except the author's own study (Tanimura and Mattes, 1993).…”

Qualidade química e perfil sensorial da cerveja envelhecida em barris de diferentes madeiras

“…A extração por solvente apolar e leitura espectrofotométrica, que foram desenvolvidas para quantificação de substâncias amargas do lúpulo (EBC, 2004;ALDERTON et al, 1954), porém estes procedimentos analíticos não possuem alta especificidade para compostos de amargor do lúpulo (BUCKEE, 1985), o que gera um efeito residual na leitura sob espectrofotômetro ao somar outros compostos que contêm estrutura hidrofóbica e são, portanto, também extraídos pelo solvente apolar empregado.…”