The Basics of Hops
"If one intends to make beer from oats, it is prepared with hops."
Abbess Hildegard of Bingen
(the oldest surviving written record of the use of hops in beer)
History of Hops
For centuries, hops have been a beloved component of beer. They are a natural preservative and act as the primary contributor to flavor and aroma. Described as floral, herbal, spicy or citrus, hops are capable of imparting nearly any flavor — the “spice of beer.”
Today, beer without hops seems inconceivable, but from a historical perspective, it is a recent practice. Even though hop cultivation can be traced back to 736 AD in the Hallertau region of southern Germany, commercial production for brewing was not documented until 1079 AD. Six centuries later, hops made their way to the United States.
Despite immediate growth in the United States, the increased use of hops in brewing was developed by the British. During the 18th and 19th centuries, Britain shipped beers to their Indian colony. Unfortunately, beers spoiled during this long journey, leaving brewers with two options: increase the alcohol content or the amount of hops used. Ultimately, the India Pale Ale was born as hops were added later in the brewing process to increase antimicrobial activity and diminish spoilage rates.
While the British were mastering hop forward pale ales, the New England colonists were increasing production and usage. Unfortunately, by the late 1920s, devastating diseases such as downy mildew and powdery mildew destroyed nearly all of the east coast crops, leaving domestic production to the increasingly efficient west. Today, the United States is responsible for producing more than 30% of the world’s hops, virtually all of which can be found in Northwest’s Yakima and Willamette Valleys.
What Are Hops?
Hop plants, Humulus lupulus, are vigorously climbing perennial vines. They are dioecious in nature, meaning the male and female hops flower on different plants, however only female hop cones are suitable for brewing because their lupulin glands contain valuable resins that are paramount in establishing the flavor and aroma of beer. Male hop cones are solely used for breeding.
The major hop components of brewing can be classified into three categories: alpha acids, beta acids, and essential oils. Of these, alpha acids are considered to be the most important. During the brewing process, alpha acids are converted into iso-alpha acids and function as the beer’s principal bittering agent. Beta acids do not isomerize during the brewing process, but they do provide small amounts of bitterness, numerous flavor compounds and antimicrobial properties. Essential oils are primarily responsible for the flavor and aromatic qualities. They are highly volatile and dissipate during boiling, however late hop additions and dry hopping can trap these oils and provide sensory characteristics brewers describe as floral, herbal, spicy or citrus.
While all hops can provide both bitterness and aroma, they are generally only classified as an aroma or bittering hop. Aroma hops are typified by low alpha acids, higher levels of beta acids and an oil profile associated with favorable aroma. Because of this, aroma hops are generally used as a finishing or conditioning hop. Bittering hops on the other hand, have higher levels of alpha acids and are generally only used to bitter beer since the aromatic qualities of the hops are lost in the boiling process. Most varieties serve only one purpose, however, some hops such as Cascade, Centennial, Warrior®, Columbus and Northern Brewer are considered to be dual purpose and can be added to the boil at any time.
Components of Hops