Labels:text | font | screenshot | black and white | document OCR: Hopunion U.S.A ., Inc. AROMA Much is spoken of the organoleptic quality and intensity of dried hop aroma. These are again strong varietal characteristics. There does appear to be a general relationship between the type and heaviness of a hop aroma and the flavor and aromatic properties of a resultant beer. However, this relationship can be obscured by the manner of using the hops. A skilled, comparative aromatic evaluation of samples of one variety can detect those samples which have been picked too early or too late, overdried, or stewed. Moreover a trained evaluation can select particularly favorable growths of a variety from within the normal range of aroma exhibited by that variety in a particular season. ALPHA ACIDS These are a major component of the soft resins. When isomerised, these materials provide the main bitter compounds associated with beer. The alpha acids content varies widely amongst hop varieties from levels of 3-4% w/w in aromatic type hops to levels of 13-14% in the bitter hops. BETA ACIDS Another soft resin component, the beta-acids, are not bitter in the natural or isomerised form. Some of the oxidation products do provide bitterness, and the beta-acids can be chemically transformed into light-stable bittering forms. CO-HUMULONE The alpha acids exist in three analogous forms, humulone, ad- humulone, and co-humulone; and the proportions of these analogues vary markedly with variety. It is widely held that relatively high levels of co-humulone produce a harsh, unpleasant bitterness and have a negative impact on head retention. Although this belief is still being questioned, varieties with relatively low co-humulone levels are still strongly favored. STORAGEABILITY Oxidation of alpha acids removes their ability to be isomerised to the required bitter isomers. In comparable circumstances some varieties lose a greater proportion of their alpha acids to oxidation than do others. Cold storage and anaerobic conditions can both delay oxidation, but the innate property of a variety in this context is important in commerce. Interestingly, some 3
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