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Processing Homegrown Hops

So you planted some hop rhizomes, watered them, trained them up a trellis or twine and now they are sporting an abundance of nice plump, flower-like cones. How and when should you harvest them? Do they need to be processed somehow? How should they be stored? How could they be used in your beer? Growing hops is an exciting addition to any home brewery. Here’s how to get a hop crop from the yard to the brew pot.

First a little background. Common Hops (Humulus lupulus) are a hardy perennial plant that dies back to the ground each winter then grows up again in the spring. The plant grows as a bine, which will wrap clockwise around anything handy and cling to it with the aid of stiff bristles on the stem. The female fruit are often referred to as cones for their resemblance to spruce cones, only green and leafy. These are the hops that we know and love in our beer. The place where hops are grown is referred to as a yard.

Harvesting

Knowing when hops are ready to harvest is an art that combines the senses of sight, smell and touch. Hops are ready to harvest when the cones are a deep green color, but before they start to develop any brown color, which usually begins on the very tips of the bracteoles (the little leaves that make up the cone-like flower). The other important visual clue is the development of lupulin, a powdery yellow substance that forms in tiny glands near the base of each bracteole. At first the glands containing lupulin are very pale yellow, but as the cone matures, the gland and lupulin attain a deep yellow color in contrast to the deep green color of the bracteoles. When you suspect your hops are nearing harvest, simply pick a few cones and either pull them apart or split them lengthwise with a sharp knife to get a better look at the lupulin.

While you are manipulating the hops cones to get a look at the lupulin, you should also rub them between your thumb and fingers and smell the resulting aroma. If the hops are ready to be picked the aroma should be quite pronounced. If you pick an immature cone, the aroma of lupulin will be detectable, but faint.

The last clue to the harvest readiness of your hops is to gently squeeze the cones between your fingers. A hop cone ready for harvest will feel papery, rather than succulent. It will spring back when squeezed, rather than remaining squashed, after you release it. The other thing to feel for is the stickiness of the lupulin when rubbed between your fingers. The quality and quantity of lupulin in a ripe cone will leave a resinous sticky yellow residue on your fingers. Your fingers should develop a sticky lupulin glaze on them after several minutes of picking. With experience, you will soon be able to compile all of the sensory indicators to determine when your hops crop is at the peak of harvest readiness.

Harvesting hops on a commercial scale involves cutting the bines and feeding them into large specialized machines that strip the cones from the plant. Before the advent of such equipment, hops were harvested by hand by multitudes of seasonal employees. For home hops growers, harvesting hops by hand the “old-fashioned” way is the only practical method to get the job done. I harvest my hops by climbing a ladder to reach the top of the bines and work my way down. I fasten an empty ice cream pail by the bail onto my belt so it hangs at my hip, allowing me to pick with both hands and drop the cones easily into the pail. Some folks use a mesh bag or fruit-harvesting bag slung over their shoulder or fastened about their waist to stuff the cones into as they pick. Another harvesting approach, if you are not comfortable working from a ladder, is to lower the bines to the ground and then pick the cones from them.

In a commercial operation, the hop harvest is done all at once, which terminates the plants for that growing season. If you choose to cut your bines down to harvest them, rather than climb a ladder, you will reduce the potential quantity of hops you harvest that year, but save yourself trips up and down a ladder.

If you don’t mind the climbing, proceed with caution and avoid over-reaching while picking. Picking from a ladder while leaving the bines intact allows you to pick only the cones that are ready at a given time, then come back to pick more later. Also, hop bines will continue to produce some new cones throughout the growing season if left in place to grow. After you pick the first batch of cones from your bines you can return every two to three weeks to pick again until the end of the season. Where I live in western North Dakota (47 °North latitude) I pick hop cones from about the middle of August to late September. Places farther south would begin harvest earlier and can continue later into the growing season. Hop cones should always be handled gently during harvest and handling to minimize the loss of lupulin.

Drying

After harvesting hop cones they will need to be dried as soon as possible. Drying hop cones will permit them to be stored for an extended period of time and provide a uniform product that can be weighed to consistently determine quantities for use. Hops can be dried in a variety of ways depending on your climate and facilities at hand. If you have a food dehydrator, spread the hop cones in a single layer on the dehydrator trays and run the dehydrator between 90 °F and 115 °F (32 and 46 °C). Depending on conditions, it may take up to several hours to dry the hop cones sufficiently for storage. The cones are dry (very light and papery) when they have opened up, and make a rustling sound when handled.

If you do not have a food dehydrator, hop cones can be dried by spreading them out on screens or cloth in a place where they are protected from the elements. Before I owned a food dehydrator, I spread my hop cones on old window screens propped up on wooden blocks in the attic above my garage. I left the access door to the attic open to allow for air flow, and the hops dried nicely in a couple days during the heat of late summer.

Storage

Once the hop cones are sufficiently dry, they should be handled carefully and placed in some type of sealed container for storage. Unless the hops will be used shortly after drying, they should be stored in the freezer to prevent deterioration.

A vacuum seal-and-store machine that draws the air out of a plastic pouch then seals it shut is a good way to store your hops. Weigh out either a half or full ounce of hops and place them in a plastic pouch designed for your machine and process them according to the manufacturers’ instructions. If you do not have a seal-and-store machine, good quality zip-seal freezer bags also work well. I place my dried hops in a zip-seal bag and press the seal closed until only a small opening remains, then press most of the air out of the bag, and quickly close the remaining seal. Other types of containers that seal tightly, like foil coffee bags (read more about this method at www.byo.com/mrwizard/923.html), will also work to store hops if you prefer not to use plastic bags. Once your hops are securely stored in the container of your choice, simply keep them in the freezer until use. If the stored hops lose color or start to look like frozen spinach, you may not want to use them in your brew. I have successfully stored hops in plastic zip-seal bags in the freezer for up to two years before using them in any of my brews.

Using homegrown hops

Homegrown whole hop cones can be used in the same manner as store bought hops by adding them to the boil, placing them in a hopback, or using them to dry hop in the fermenter. I usually place my hops in a cheesecloth bag tied shut with a piece of cotton string, before adding them to the boil. This prevents the hops from clogging the spigot on my brewpot when I transfer the wort from kettle to carboy. I also use homegrown hops to dry hop some of my beers in the secondary fermenter. Homegrown Cascade hops work particularly well for dry hopping pale ales.

Perhaps the biggest challenge in using homegrown hops for bittering is not knowing their alpha acid content. Alpha acid content is not a critical issue when hops are used in a hopback or to dry hop beer because the hops are not boiled to produce bitter isomers of the original alpha acid. However, if the hops are to be added to the boil, the alpha acid content is a significant factor in the resulting bitterness of the finished beer.

While some preliminary experiments have been conducted in an attempt to link the pH of hop tea to alpha acid content, these experiments have not been sufficiently broad in scope to serve as a reliable indicator of alpha acid content of hops (if this was possible commercial brewers would have done this long, long ago as alpha acid determination is a pain). Another approach that can be used to determine hop bitterness level is to brew some tea by boiling a hop of known alpha acid content and compare it in taste to a tea brewed with the same quantity of unknown alpha acid hops. While this method is also very subjective, it may provide some insight into your hops’ alpha acid content.

Another approach to get an idea of your homegrown hops’ alpha acid content is to look at the typical alpha acid content for the varieties of hops that you grow (see the online hop chart at www.byo.com/referenceguide/hops/) and use that as a starting point for using your hops in the boil. I used this logic when experimenting with my own homegrown hops. After checking the expected alpha acid content from the chart, I brewed a few batches with my own hops and found that their apparent alpha acid content seemed quite low (around 2%) compared to the bitterness I achieved with similar hops of known alpha acid content used in the same recipe.

Growing your own hops can be a very rewarding complement to any home brewery. With a little luck and experimentation you to can produce, process, store and use your own treasured herb of beer. Then you can also take pride in brewing beer that includes a vital ingredient that you also grew yourself.

Issue: May-June 2008