Hop (plant)
Hop
resins are composed of two main
acids: alpha and beta acids. Alpha acids have a mild
antibiotic/
bacteriostatic effect against
Gram-positive bacteria, and favours the exclusive activity of
brewing yeast in the fermentation of beer. The flavour imparted by hops varies greatly by variety and use: hops boiled with the beer (known as "bittering hops") produce bitterness, while hops added to beer later impart some degree of "hop flavour" (if during the final 10 minutes of boil) or "hop aroma" (if during the final 3 minutes, or less, of boil) and a lesser degree of bitterness. Adding hops after the boil, a process known as "dry hopping", adds hop aroma, but very little bitterness. The degree of bitterness imparted by hops depends on the degree to which otherwise insoluble
alpha acids (AAs) are
isomerised during the boil, and the impact of a given amount of hops is specified in
International Bitterness Units. Unboiled hops are only mildly
bitter. Beta acids do not isomerise during the boil of
wort, and have a negligible effect on beer flavour. Instead they contribute to beer's bitter aroma, and high beta acid hop varieties are often added at the end of the wort boil for aroma. Beta acids oxidise and oxidised beta acids form sulphur compounds such as DMS (
dimethyl-sulfide) that can give beer off-flavours of rotten vegetables or cooked corn.
"
Noble hops" are low in bitterness and high in
aroma, and traditionally consist of four
central European
cultivars, 'Hallertauer Mittelfrueh', 'Tettnanger', 'Spalter', and 'Saaz'. They contain high amounts of the hop oil
humulene and low amounts of alpha acids
cohumulone and
adhumulone, as well as lower amounts of the harsher-tasting beta acids
lupulone,
colupulone, and
adlupulone. Humulene imparts an elegant, refined taste and aroma to beers containing it. These hops are used in
pale lagers.
English ales use hop varieties such as Fuggle, Golding and Bullion. North American varieties include Cascade, Columbia, and Willamette. Certain
beers (particularly the highly-hopped style known as
India Pale Ale) can have high levels of bitterness.
Flavours and aromas are described using terms which include "grassy", "floral", "citrus", "spicy", and "earthy".
Medicinal use
The medically active ingredients in Hops are humulene and
lupulene.
Dried female buds have a high
methylbutenol content, which has a mild
sedative effect on the
central nervous system; it is used in the treatment for
insomnia,
stress and
anxiety. If one has trouble getting sleep, hop tea before going to bed may help, though a quantity of beer has similar results.
Hops'
antibacterial qualities also stimulate
gastric juice production.
Fibre
The stem is flexible and very tough, with a tenacious fibre that has been used in some cases to make
cloth and
paper.
Other uses
Tender young hop shoots, which are only available for about three weeks during spring, were mainly eaten by the poor in
medieval times, and was a substitute for
asparagus. Only recently have they been rediscovered as a
delicacy in parts of Germany, Belgium and England. They are served raw with
vinaigrette, or boiled with fresh herbs or fried in
batter.
Wild hops are also relished by
cows,
horses,
goats,
sheep, and
pigs.
* Lee W. Janson, Ph.D.;
Brew Chem 101; Storey Publishing; ISBN 0-88266-940-0 (paperback, 1996)
*
Purdue University article*
Hop Farm Museum in Kent Hopping in Kent.
*
Portal to many sites on hopping and society*
Hops varieties research*
Hallertau hop shoots*
Botanical.com - a wealth of information on the Hops plant and its past and modern uses*
Armeniapedia.org - Medicinal uses of hops in Armenia*
Cancer preventive properties of Xanthohumol*
Belgian website about hops
