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ANALYTICAL EVALUATION OF α‐ACIDS IN HOP EXTRACTS AND IN HOPS *
Author(s) -
Verzele M.,
Dyck J. Van
Publication year - 1971
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.2050-0416.1971.tb03417.x
Subject(s) - conductometry , titration , chemistry , hop (telecommunications) , chromatography , dimethylformamide , analytical chemistry (journal) , octane , inorganic chemistry , organic chemistry , computer science , computer network , solvent
The results of new investigations on hop extract analysis are presented. The main findings are:1 The specific extinction (257) of α‐acids at 276 nm in iso‐octane used at present in CCD and paper strip analyses is 3·5% too high: analytical results have therefore been too low. The new extinction value to be used is 248. 2 The result of paper strip analysis depends very much on the amount of α‐acids placed on the strip. The three‐point paper strip method can only partly correct this. In general, figures with paper strip analysis have a tendency to be too high. 3 Conductometric titration of α‐acids produces a figure about 2 to 10% too low. This can be partly corrected by adding 20% dimethylsulphoxide or dimethylformamide to the titration medium. 4 Conductometric analysis of hop extracts with removal of “iso‐α‐acids like material” before titration is possible by a very simple procedure (pH 7 buffer extraction).New photometric and conductometric procedures based on these results give figures which are in agreement for something which must be practically true α‐acids.