One of the four essential ingredients of craft beer is hops, Humulus lupulus, a first cousin to cannabis which derives its Latin name from the same root as the wolves that the plant’s wild growth is likened to. Hops are female flowers, normally called cones, from the hop plant and look like one-inch, miniature artichokes.
Hops are used as preservatives, for aroma, and to add flavoring to beer. The hop tastes and bouquet, obtained from hop oils and resins which cannot be duplicated with any other plant, are used to either balance the rich sweetness of the malt or stand out separately. The bitterness, used to balance the rich sweetness of the malt, comes from alpha acids in the hops. Beta acids and tannins help stabilize the beer and act as preservatives by warding off bacteria. Hop varieties are hybridized to emphasize aroma, flavoring or bitterness characteristics.
The renowned abbess Hildegarde Von Bingen, in her book on herbal plants Physica Sacra written about 1067, was the first person to describe the preservative properties of hops.
The perennial hop plant spirals as a vine up to 25 feet and is usually grown on a string or pole. In the United States the most important hop growing area is the Pacific Northwest, with about 41,000 acres of hops (2008). The hop flower is usually used dried for brewing beer and most often pelletized.
Hops provided at the beginning of the brewing boil add dryness and bitterness; those added later have greater influence on the aroma. Sometimes hops also are added during fermentation in a procedure called "dry hopping" which can heighten both the aroma and bitterness.
The bitterness of beers, measured in the International Bitterness Unit (IBU), gives a guide to the level of the bitterness. A lite beer may have 10-15 IBUs, an English Mild Ale about 20 units, a Czech Pilsner and a British-version India Pale Ale both about 40, Around 35 IBUs, the hop character begins to emerge, and over 40 becomes somewhat prominent depending on the malt backbone.
The IBUs measure bitterness according to the chemical levels of hop acids. However, malt is often used to balance the hop bitterness and, with sufficient malt backbone, beers high in IBUs do not appear extremely bitter. This is known as perceived bitterness.
Bittering or boiling hops primarily are used for adding bitterness, while finishing or aromatic hops are used mainly for aroma and delicate flavors. Most finishing hops are from Europe and known as noble hops including Hallertau, Tettnang, Herbruck, Spalt, Saaz, and sometimes Fuggle and Golding. Pacific Northwest bittering hops include: Cascade, Chinook, Amarillo, Northern Brewer, Nugget and Colombus/Tomahawk/Zeus (CTZ).
Cascade hops are by far the largest volume of hops used by American craft breweries. Cascades provide flavors of citrus, floral and alfalfa. Other hops and flavors include Simcoe (grapefruit, pineapple, pine), Centennial (juicy fruit, fruity, citrus), Chinook (pine, pepper), Amarillo (apricot, peach), and Columbus/Tomahawk/Zeus (dark fruit, spices, onion).
Among the hoppiest beers available are Dogfish Head 90 Minute IPA (9% alcohol by volume-ABV, 90 IBUs), Dogfish Head 120 Minute IPA(17% ABV, 120 IBUs), Double Daddy Imperial IPA (9.5% ABV, 102 IBUs) from Speakeasy Ales & Lagers in San Francisco, CA, Hedonism Ale (7% ABV, 110 IBUs) from Legacy Brewing of Reading, PA, and Ruination IPA (7.7% ABV, 100+ IBUs) brewed by Stone Brewing of Escondido, CA.