Humulus Lupulus

The whole is equal to the sum of its parts, or so I've been told. In beer, the parts are water, malted grain, hops, and yeast. There are often other ingredients too, but all beer that is made correctly contains at the very least water, malted grain, hops, and yeast. So in order to better understand the “whole” in this case, it helps to better grasp the individual parts. Make sense?

Today, the beer “part” that I am focusing on is everybody’s favorite – hops. Most of us are aware by now that hops are little plants that make the beer bitter. What you probably didn't already know is that there are literally thousands of other things to know about hops. I won’t be able to go into them all, but we can scratch the surface enough attain insight.

Glorious hop flowers

Humulus Lupulus (hops) are the flowering cone of a perennial vining plant and a cousin of the cannabis variety (sorry no THC in this stuff) that typically thrives in climates similar to the ones that grapes do. Hop plants are dioecious, meaning the males and females flower on separate plants -- and the female cones are used in the brewing process. Hops season the beer, ward-off spoilage from wild bacteria and bring balance to the sweet malts. They also lend a hand in head retention, help to clear beer (acting as a natural filter) and please the palate by imparting their unique characters and flavors.

Old school brewing

Before there were hops, there was gruit. Gruit was a combination of herbs that were used to flavor and bitter ancient beer. Some of the most common herbs that were used in gruit, such as sweet gale (Myrica gale), mugwort (Artemisia vulgaris), yarrow (Achillea millefolium), ground ivy (Glechoma hederacea), horehound (Marrubium vulgare), and heather (Calluna vulgaris) were mildly to moderately narcotic. Gruit varied somewhat since each gruit producer included different herbs to produce unique flavors and effects. Other adjunct herbs found in gruit included black henbane, juniper berries, ginger, caraway seed, aniseed, nutmeg, cinnamon, and even hops in variable proportions.

The story of how the brewing world came to abandon gruit in favor of hops varies by region and by time. Hops originated in China from where they moved east- and west-wards. The first documented instance of hop cultivation in Europe was in 736, in the Hallertau region of present-day Germany, although the first mention of the use of hops in brewing in that country wasn't until 1079. However in the will of Charlemagne’s father, Pepin the Short, in 768 hop gardens were left to the Cloister of Saint-Denis. Not until the 13th century did hops begin to start threatening the use of gruit for flavoring—which was used depending on the taxes that the nobility and the church levied on either hops or gruit – whichever one was taxed made the brewer quickly switch to the other one.

In Britain, hopped beer was first imported from Holland around 1400, but hops were condemned in 1519 as a "wicked and pernicious weed" and thus couldn’t be grown in England. Hops were imported from France, Holland and Germany and naturally import duty was raised on those. It wasn’t until 1524 that hops were first grown in the southeast of England (Kent) when they were introduced as an agricultural crop by Dutch farmers. It was another century before hop cultivation began in the present-day United States, in 1629 by English and Dutch farmers.

The 48th parallel covers both Germany and
the Pacific Northwest of the USA

Today, Hops production is concentrated in moist temperate climates, with much of the world's production occurring near the 48th parallel north. Important production centers are the Hallertau in Germany, the Yakima (Washington) and Willamette (Oregon) valleys, and western Canyon County, Idaho. The principal production centers in the UK are in Kent (which produces Kent Goldings hops) and Worcestershire. As of 2010, Germany produced the most hops in the world (34,249 metric tons) with the United States coming in second (23,701 metric tons).

Hops are usually dried in an oast house (drying house) before they are used in the brewing process, but are sometimes used to make "wet-hop" beer immediately after a harvest and without drying. They are also often processed into hop pellets prior to being used for brewing. Hops are added in varying types, times and quantities throughout the boil of the wort (young beer), depending on what the brewer is trying achieve. In very simple terms, the brewer adds the hops to flavor the beer at the beginning of the boil and adds the hops to increase aroma at the end of the boil. Beyond that, many brewers add additional hops during the fermentation process (called dry hopping) in order to further increase the strong “hoppy” aromas in the brew.

Cross section of a hop cone

The money of the hop is found in the resins that are contained within, which are composed of two main acids: alpha and beta acids. Alpha acids are responsible for the bitter flavor in the beer, have a mild antibiotic effect, and favor brewing yeast during the fermentation process. Beta acids do not isomerize during the boil of wort, and have a negligible effect on beer taste. 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.

As you can imagine, hops are categorized into two groups: bittering (or flavoring) hops and aroma hops, depending on whether they are high in alpha acids or high in beta acids. The bittering hops are generally boiled for 60-90 minutes in order to maximize the isomerization of the alpha acids and impart as much flavor into the finished product as possible. European strains, such as the noble hops, typically average 5–9% alpha acids by weight (AABW), and the newer American cultivars typically range from 8–19% AABW.

Aroma hops usually have a lower concentration of alpha acids (~5%) and are the primary contributors of hop aroma and (non-bitter) flavor. Aroma hops are typically added to the wort later to prevent the evaporation of the essential oils. They are added with 30 minutes left to impart a non-bitter hop taste and/or with 10 minutes left to impart aroma notes. The three major components of the essential oil of hops are myrcene, humulene, and caryophyllene, which comprise about 60–80% of the oil for most hop varieties. There are over 250 components of essential oils that have been identified, but only 22 are known to have significant influence on the flavor and aroma.

A casual stroll through a hop farm

Flavors and aromas are described appreciatively using terms which include "grassy", "floral", "citrus", "spicy", "piney", "lemony", "grapefruit", and "earthy". Many pale lagers, such as the ones made by big beer, have fairly low hop influence, while lagers marketed as Pilsner or brewed in the Czech Republic may have noticeable noble hop aroma. Certain ales (particularly the highly-hopped style known as India Pale Ale, or IPA) can have high levels of hop bitterness.

Particular hop varieties are associated with beer regions and styles, for example pale lagers are usually brewed with European (often German, Polish or Czech) noble hop varieties such as Saaz, Hallertau and Strissel Spalt. British ales use hop varieties such as Fuggles, Goldings and W.G.V. North American beers often use Cascade hops, Columbus hops, Centennial hops, Willamette, Amarillo hops and about forty more varieties as the U.S.A. have lately been the more significant breeders of new hop varieties, including dwarf hop varieties. For a fairly complete list of hop varieties and their characteristics, click here.

So, I think I've given you enough information about hops to last a life time. The next time you drink your favorite craft beer, and the flavors and aromas hit you, you’ll have a better understanding of what they are and where they come from.

Here’s to craft-brewed happiness… Cheers!