What are Hops?

The Hop Flower (or cone) Source: Wikipedia

The Hop Flower (or cone)
Source: Wikipedia

We talk a lot about hops, but, what exactly are hops?

In brewing, hops provide a bittering agent to contrast or balance the sweetness of malt, provide aroma, act as a preservative, aid with head retention, and provide a unique profile to a beer.

Hops are the female flowers of the plant humulus lupulus, a perennial climbing plant that will grow up to 18 feet tall and is native to North America, Europe and Western Asia. It tends to grow in the same soil that potatoes prefer and prefers a soil that is rich in boron, but depending on the qualities of the soil and climate, a hop from one region will taste very different from a hop from another region.

The lupulin gland in a hop cone
Source: Wikimedia

Being a climbing plant, like grape vines, farmers use trellises to help them grow; this produces a heartier crop because trellises free up energy that would’ve been used for structural growth. Because seeds are undesirable for brewing, farmers only plant female plants in hop fields. They’re planted in rows 6 to 8 feet apart and in the spring, the plants begin to grow, with the hop flowers, or cones, near the top. Harvest comes near the end of summer, when the cones are taken to a hop house for processing.

The cones themselves contain a gland called the lupulin gland, which is yellow and waxy, and it contains alpha acids that provide bitterness and essential oils that provide flavor and aroma.

The hop plant prefers a temperate climate and grows mostly along the 48th parallel north latitude. In fact you may have seen the Sam Adams beer called Latitude 48, which makes references to this zone.

The 48th Parallel crosses Germany, Austria, Hungary, China, France, Russia, Slovakia, Ukraine, Moldova, Kazakhstan, Russia, Canada, and the United States. No surprise, in the U.S., the 48th parallel crosses Washington state, where the most of the hops in the United States are grown.

Hops can also be classified into two very broad categories: bittering hops and flavor/aroma hops. Bittering hops have higher alpha acid, lower essential oils, and provide the bittering quality. Aroma and flavor hops have lower alpha acid and higher essential oils, and, of course, are used to provide aroma. Bittering hops are used early in the beer boil, whereas flavor hops are added when there about 15-20 minutes are left. Aroma hops are typically added near the end within minutes of the end of the boil. Some brewers also use a technique known as dry hopping where they add hops during fermentation. This increases both bitterness and aroma.

Dry hopping, or adding hops during fermentation
Source: Drew's Brew Reviews

Hops are also divided further into subcategories based on region: Continental, English or American. Continental hops (also known as Noble hops) grow in central Europe, and are low in bitterness and have a strong floral or spicy aroma. English hops are also low in both bitterness and have an herbal or grassy aroma, while American hops vary wildly, with some providing both a high amount of bitterness and aroma. From there hops are divided even further into regions or other subcategories.

Historically, the first documented cultivation of hops can be traced back to 736 AD, but the first documentation of using hops in beer doesn’t come until 822 in a series of German legal statutes describing tithes to a monastery. However, it wasn’t until the 13th century that hops began to see serious use in commercial brewing, as before hops came along (or later when the nobility imparted high taxes on hops) brewers would use gruit, which is a mixture of herbs and spices that brewers used to flavor their beer.

The dominance of hops in brewing really started after April 23rd, 1516, when Bavaria instituted the German Beer Purity Law and declared that hops were one of only three ingredients allowed in beer. And then in 1710, England declared that hops were the only bittering substance allowed by law in brewing, so that brewers wouldn’t skirt the hop tax of a penny per pound.

Lastly, hops aren’t just used for beer. In some countries they’re used for soft drinks and they’re often used as an herbal medicinal treatment for anxiety and insomnia. Studies are also currently under way to investigate the use of hops as relief for menstrual problems and there is some evidence that they may be used in the fight against cancer.

Sources: A Perfect Pint, HomeBrewers.com, Drugs.com

Note: this originally appeared as part of Episode 22.