Humulus Lupulus, meaning "
Wolf Plant", is a
perennial climbing vine commonly known as
hops. It is used, along with
malt,
yeast and
water in the production of
beer. The hops plant is closely related to
Cannabis and the
nettle, and is said to have slight
narcotic effect.
Hops is indigenous to Italian peninsula and was eaten as a delicacy by the Romans. As the Roman Empire expanded, so did the cultivation of hops. When the Roman Empire collapsed, it was taken north into central Europe as people migrated. The advance of hops was slow, only arriving in the British Isles in 15th century. It now grows wild in much of Europe.
The primary use of hops is in brewing, where it is used both for bitterness and flavor. The fermentation of malt creates lots of sugar, and hops provides the counter balance. From a practical standpoint, hops also acts as a natural preservative and prevents bacterial infections during the brewing process.
Beer was being made long before hops was widespread. Originally, a mixture of herbs and spices known as gruit was used as a flavoring, but some brewers in central Europe discovered hops and began using it as a substitute. The gruit market, controlled by the Church in many parts of Europe, fought hard to get hops banned, but hops eventually won out due to its superior flavor.
Hops is dioecious, meaning there are separate male and female varieties, but only the female plant is used in beer making. In the majority of cases, the males are culled to prevent it from mating with the females, as unmated females have a stronger aroma and less bitterness, generally preferred for lagers. Ale brewers, primarily in the British Isles, use mated hops, which has a more intense bitterness. The cone-like hops flower contains resins known as alpha acids (humulones) and beta acids (lupulones), plus various oils. The alpha acids provide the bitterness, the beta acids and tannins stabilize the beer and serve as a disinfectant and preservative. The oils, which attract bees and other insects to the hops for pollination, provide the flavoring that appeals to humans and bugs alike.
Hops are harvested in early autumn, and they must be dried quickly to avoid going moldy, in special oast houses close to the fields where they are grown. They are then compressed into sacks, which prevents oxidation of the alpha acids, and stored in a dark place to avoid the breaking down of the oils. Most are then milled into powder and compressed into pellets, then boiled in the wort to extract the the alpha and beta acids. Some of the the hops are used whole, particularly in the flavoring stage of ales; these hops are added later, to avoid breaking down the flavoring oils.