DIRECT ANALYSIS OF INDIVIDUAL ANALOGUES OF ALPHA-ACIDS, BETA-ACIDS AND 4-DESOXYHUMULONES IN HOPS USING GAS-LIQUID CHROMATOGRAPHY AND NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY

The techniques of gas‐liquid chromatography and nuclear magnetic resonance allow simultaneous analysis of the individual α‐acids and β‐acids and the corresponding 4‐desoxyhumulones. The rates of appearance in the growing hop‐cone of humulone, lupulone, 4‐desoxyhumulone and their co‐homologues and ad‐isomers are reported. The results indicate a relatively enhanced initial formation of the 4‐desoxy compounds and β‐acids. The α‐acids reach their maximum concentration later than the desoxyhumulones and β‐acids but eventually become the predominant group. It appears that formation of the α‐acids is associated with a decline in the relative proportion of both β‐acids and 4‐desoxyhumulones. For each class of compounds, the co‐homologues increase their relative concentrations during the growth of the hop; adhumulone and adlupulone remain in almost constant proportions during this period. 1969 The Institute of Brewing & Distilling