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DETERMINATION OF ISOHUMULONE AND ITS ANALOGUES IN BEER
Author(s) -
Howard G. A.,
Tatchell A. R.
Publication year - 1957
Publication title -
journal of the institute of brewing
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.523
H-Index - 51
eISSN - 2050-0416
pISSN - 0046-9750
DOI - 10.1002/j.2050-0416.1957.tb02912.x
Subject(s) - chemistry , hydrochloric acid , sodium hydroxide , chromatography , gas chromatography , methanol , hydrogen peroxide , extraction (chemistry) , organic chemistry
Gas chromatographic methods have previously been successfully applied to the detailed analysis of the hop resins, and this convenient analytical technique has now been used to determine the proportions of isocohumulone, isohumulone and isoadhumulone in the total bitter substances of beer. The iso‐compounds are extracted with light petroleum together with contaminants (“background”) which are then washed out with a mixture of methanol and hydrochloric acid; the iso‐compounds are finally quantitatively extracted by sodium hydroxide solution, and a portion of this final extract is used for the determination of total bitter substances, using ultraviolet spectroscopy; the remaining portion is then oxidized with hydrogen peroxide and the fatty acids characteristic of each analogue which are thus obtained are analysed by gas chromatography. In developing this method, additional information has been obtained concerning the amount and nature of the “background” material extractable from beer, this material being divisible into three main fractions, one of which contains a mixture of humulinic acid and its analogues. The proportion of cohumulinic acid in this group is different from the proportion of isocohumulone in the total iso‐compounds present in the same beer. The remaining two fractions in the “background” material also appear to comprise a mixture of analogues.