The following are definitions of some of the technical terms on this site. If you require any further clarification about these or any other terms, please contact us.
Much is spoken of the quality and intensity of dried hop aroma. These
are strong varietal characteristics. There appears to be a general
relationship between the type and heaviness of a hop aroma and the
flavour and aromatic properties of beer.
A major component of the soft resins. When isomerised, these materials
provide the main bitter compounds associated with beer. The alpha acid
content varies widely among hop varieties from levels of 3 - 4% w/w in
aromatic type hops to levels of 13 - 16% in the bitter hops.
A soft resin component, 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
The alpha acids exist in three analogous forms, humulone, ad-humulone
and co-humulone; and the proportions of these analogues vary markedly
with variety. Varieties with relatively low co-humulone levels are
Where available, analytical figures on varietal sheets show the % of
Alpha Acid remaining after 6 months storage at 68f. 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 others do. Cold
storage and anaerobic conditions can delay oxidation. Some oxidation of
essential oil components is necessary to produce compounds thought to be
important in beer flavours, so controlled ageing is important for hops
required for both bittering and aromatic properties.
This characteristic varies widely with seasons, varieties and growths
from 0.5 mls to about 3 mls per 100g of hops. While the soft resin
compounds are responsible for providing the bitterness to a beer, the
quantity and composition of the essential oils are responsible for the
amount of hop flavour and aroma in the beer.
|MYRCENE, HUMULENE, CARYOPHYLLENE & FARNESENE:
The four major components of the essential oils and between them they
account for about 60 - 80% of the essential oils for most varieties. The
compounds are all highly volatile hydrocarbons and during boiling of
the wort most, if not all of them, are driven off and contribute only a
little to hop flavour and aroma in beer. Therefore it is usually
necessary to add late hops for additional aroma.