Hops are amazing things. These little cone-shaped flowers give beer it’s bitter taste as well as a huge range of aromas and tastes. The hops we use for beer are actually the female flowers of the hop plant, Humulus lupulus. Hops were originally used more for their antibacterial purposes than solely for their taste, but this amazing little flower is focused more on flavor and aroma today, but is still relied upon to help keep unfavorable bacteria out of your beer.
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Some Background on Hops
Before getting into the anatomy of a hop, it’s a good idea to have a primer on what hops are and where they come from. Hops were first used in brewing around the 11th century, with other flowers and herbs used before this for bittering. These included dandelion, burdock root, marigold, horehound, ground ivy, and heather.
The production of hops is concentrated in moist, temperate climates, which means much of the world’s production takes place near the 48th parallel north. Hop plants prefer the same soils as potatoes, so the leading potato-growing states in the United States are also major hops-producing areas. While this doesn’t mean hops can grow everywhere potatoes are found, it’s usually a pretty good indicator.
Harvest time for hops comes at the end of summer, when the bines (yep, not vines) are pulled down and the hop flowers are taken to a hop house or oast house for drying. Hop houses are typically two-story buildings of which the upper story has a slatted floor covered with burlap. It’s here that the flowers are poured out and raked even. A heating unit on the lower floor is used to dry the hops. When dry, the hops are moved to a press where two long pieces of burlap are laid into the hop press at right angles, the hops are poured in and compressed into bales. These hops can be used and considered “fresh hopping” or “wet hopping.”
From here, hops can be processed further and pelletized so they can be used all year. This helps to preserve most of the hop oils so they can provide the flavor and aroma you expect, but the hops can also not be processed at all and left in whole cone form. This is an expensive way to brew and usually is only done directly following the hop harvest, so the hops are as fresh as possible.
There’s more to a hop than where it’s grown and how it’s used though. Hop flowers are incredibly intricate and delicate structures that few people ever get to truly appreciate. Since it’s a crime to not fully respect this baron of beer, it’s time we all got an anatomy lesson on our friend the hop.
The Anatomy of a Hop
There are four major pieces of a hop, and contained in these three structures is all of the hop’s magic. Starting at the base of the hop you have the Strig. The strig is the footstalk of the flower and is where the hop connects to the bine of the plant. Most of the tannins found in a hop cone are located in the strig. These tannins actually give the hop medicinal properties via polyphenols. Hops actually contain one of the highest levels of polyphenols in plants at about 4-6% by weight. These are a major contributor to the harshness or smoothness of the bitterness of a particular hop. Because of this, the length of the strig is important in the brewing process.
Next up is the Bract. The Bract is basically the hop leaves and makes up the outer structure of the hop flower. When brewing, this is the section of the hop that is discarded after brewing. Hop bracts contain polyphenols that have actually been proven to help fight dental disease, making these dregs actually worth saving!
Moving inside the hop you have the Bracteole. These are the structures inside the hop flower that support it and give it structure. These are also where you find the final piece of the hop puzzle, as the bracteole is the home to the best part of the hop. while the lupulin glands (more on them in a minute) are the major source of flavor, bitterness, and aroma from hops, there are key components found in the leaves of a hop cone that give their own help to the process. Hop cones literally ooze lupulin, giving even more ammo to help your beer out.
The part of the hop we as beer lovers and brewers are interested in are the very fragile and sensitive Lupulin Glands. This is where the resins and essential oils in a hop live, protected by the bract. If you have a whole cone hop flower you can easily see these glands by tearing the hop flower open. The lupulin glands have a yellowish pollen look to them and as soon as you expose them you should be able to truly smell the hop.
Although there are quite a few chemicals present in these glands, the three most important ones are alpha acids, beta acids, and essential oils. These three chemicals are very important in the making of beer, and are what most brewers focus on when choosing a hop for a particular brew. For more on the chemical makeup of hops, check out this detailed description.
Hops are amazingly fragile flowers and without them the bitterness and flavor we love about craft beer would be very different. There are hundreds of varieties of hops growing around the world from the Pacific Northwest to England to New Zealand. The difference in aroma, taste, bitterness, and oil content varies greatly, making new hops an always welcome announcement.
By understanding the structure of hops and how they function, you can better utilize the hops in your own brew and even enjoy a quality craft beer even more.