Dry-hopping is one of the hottest brewing techniques out there right now. It’s referenced in abundant ways, with “Dry-Hopped IPA,” “Dry-Hopped with Galaxy,” and so on adorning beer labels to signal to consumers that “there’s big hop flavor in here.” The same can’t be said for other parts of the brewing process — cold crashing or fermenting under pressure rarely make it onto beer labels, for example — and that’s because these just aren’t as sexy as dry-hopping!
More importantly, dry-hopping is one professional technique that is very easy to replicate at home. In fact, homebrewers have the benefit of being able to pile on even more hops than commercial brewers because, relatively speaking, the cost of materials is so much lower.
These are the basic considerations when dry-hopping for the first (or hundredth!) time.
What’s Going on Here? Dry-Hopping, Explained
The etymology of the term “dry-hopping” may be lost to history. Some theorize that at one time, hops came into the brewery fresh, and were used fresh on brew day. Then, when hops from that same batch were added seven or more days later, the hops had dried.
Others say the term developed because the brewer is adding them at a time when you’re no longer touching liquor (brewer’s term for water) or wort, the process requiring only tossing dry hops into a fermenter.
Though it doesn’t necessarily make sense, just know any hop added after the wort has been chilled on brew day is considered a “dry hop” no matter what form the hop comes in. As such, any hop addition to wort or beer after it has been chilled to fermentation temperatures is considered dry-hopping. At these lower temperatures, different aspects of the hops are utilized.
Why Dry-Hop? Capturing Aromas and Flavors
Alpha acids are the compound in hops that make beer bitter. However, they only produce bitterness after they have been isomerized into iso-alpha acids via a chemical process that occurs at temperatures over 175 degrees Fahrenheit. (This usually takes place during the brewing process in the boil at 212 degrees F.) Since the additions take place at cool temperatures, beer does not become more bitter from hops added during dry-hopping because alpha acids are never converted.
As opposed to alpha acids that only offer bitterness to beer, hop essential oils contain aroma compounds that supply myriad flavors including “dank,” tropical, vinous, or fruity. These oils are highly volatile and boil off or escape into the air after only minutes at high temperatures. Therefore, they are best extracted at the cooler temperatures of fermentation. Capturing these essential oils and the complex aromas and flavors contained within them is the main goal of dry-hopping.
(There are also downsides to prolonged exposure to dry hops: Polyphenols that cause astringency, a drying or rough mouthfeel, can be extracted during prolonged exposure to the vegetal matter of hops.)
Selecting Hops for Dry-Hopping
Now that it’s clear what components of hops are creating the flavor when dry-hopping, it’s time to select the type of hop to use. There are two things to consider: First, what hop varietal or varietals to use; and second, what form the hops will come in.
When selecting a hop varietal, the most relevant consideration is the flavor profile. Hop oil aroma can range from citrus to floral to woody and even coconut. Remember: It’s not only IPAs that are enhanced by dry-hopping; Farmhouse ales can gain herbal or spicy aromas, blonde ales acquire bright citrus notes, and stouts can be augmented with berry or floral flavors. A good place to explore for individual hop descriptions is hopslist.com which has an exhaustive catalog of hops and specific information and stats on each one. Or, you can simply visit your local homebrew shop and read the packaging, or ask a staff member for help.
Don’t worry too much about the “total oil concentration” of a hop. This states what percent of the hop’s mass is made up of essential oils. New research shows that hop character has more to do with the components of a hop’s essential oils (for example, the compound citronellol gives a fruity impression, while the compound geraniol has notes of flowers) than the quantity of oils contained by a single hop.
The most iconic dry hop is Cascade offering its signature mix of spicy and citrus (orange peel, grapefruit peel) aromas to legendary beers like Sierra Nevada Pale Ale and Anchor’s Liberty Ale (which popularized dry-hopping in America in the 1970s). Other homebrewing fan favorites are Citrus for intense grapefruit and lime flavor; Mosaic, carrying mango aroma mixed with pine needles and herbal notes; and relative newcomers Nelson for white wine aromas; and Galaxy for a passion fruit punch.
Whole Cone, Pellet, and Cryo Hops
Once a hop variety is chosen, it’s time to decide whether to purchase it as a whole cone, pellet, or Cryo Hop.
Whole cone hops are certainly a rustic option, but generally, they don’t benefit homebrew. Hops are added to the fermenter as whole flowers, just as they were harvested. The large amount of vegetal matter absorbs a higher quantity of beer than is necessary, and that same vegetal matter dulls the aromas extracted from the hop oil. These full-cone hops have certain uses, especially in historical styles, or if they’re purchased or plucked fresh from the harvest when they’ll impart fresh-hop flavor; but for the full impact of dry-hopping, the better options are pelletized hops or Cryo Hops.
Pelletized hops are the most common and most affordable form of hops for homebrewers, and most homebrew recipes are written based on pellet hops. To make pelletized hops, whole dried hops are crushed, the heavier parts of the plant like stems are removed, and the remaining plant matter is pressed into a pellet-shaped mold. The major benefits of this form of hop is that they absorb less beer (because some plant matter is removed), and they “dissolve” back into the hop dust they are compressed from, so wort or beer can fully surround particles and better extract oils from them.
Finally, the hot new form of hops on the scene is Cryo Hops, which, as their name indicates, are made by freezing whole hops and removing almost exclusively the lupulin glands that contain hop essential oils and acids. Since so much of the plant matter is left behind in this form of hop, the result is a fine powder that packs a serious punch of aroma and oil. The delicate lupulin glands are not pulverized when making Cryo Hops like they are when producing pellet hops, so some brewers argue the flavors are cleaner and brighter.
This product (developed by Yakima Chief and available at most homebrew suppliers) also comes as a fine powder, making absorption even more direct than the pellet hops. Producers of Cryo Hops suggest that brewers use just 50 percent of the amount of Cryo Hops that they would use of pellet hops. Of course, today’s IPA brewers would up the ante on that suggestion to pack even more hop flavor into the final beer.
Timing is (Almost) Everything
With hops in hand, it is time to decide when to add them to the wort or beer to achieve the desired flavor impact and beer appearance.
In a relatively new method, brewers are dry-hopping during primary fermentation to brew the (in)famous New England IPA (NEIPA) style.
All the effects of dry hopping during fermentation are not totally understood, but there are a few definitive results of adding “dry” hops at this time. First, when hops are added while yeast is actively fermenting, an interaction between hop polyphenols and protein occurs, which causes a permanent haze in the beer. This haze is a distinguishing characteristic of the extremely popular NEIPA style (hence the synonymous “hazy IPA” beer style). Another reaction called biotransformation also occurs. This is still being studied by brewing scientists and chemists, but the premise of biotransformation is that when hop compounds are exposed to active fermentation a transformation occurs. The transformation results in altered flavors and aromas from those the hop presents before being added to fermentation.
If the goal of dry-hopping is experimentation, then trying many different hop varieties during active fermentation is a good place to start. If a more reliable outcome is the object for your homebrew, try dry-hopping after fermentation.
The standard American IPA was built on dry-hopping after fermentation. It’s hard to think of an IPA or pale ale brewed before 2003 that wasn’t dry-hopped this way: From Stone to Deschutes, and Goose Island to Sierra Nevada, hoppy American ales were dosed with hops after fermenting and before bottling.
For homebrewers, this means waiting for activity in the airlock to cease for 12 to 24 hours before adding a dose of hops. Amounts for a standard 5-gallon batch vary from about half an ounce for something subtle like a blonde ale to more than 5 ounces for hoppy IPAs.
One major advantage to adding the hops promptly to the vessel the beer fermented in is the CO2 produced by fermentation is still filling the headspace over the beer, so there is less oxygen introduced when adding the hops. (Exposure to oxygen starts a chain of oxidation reactions that create undesirable results, like sweet cherry or cardboard flavors, and dulling of hop aroma.)
Dry-hopping after fermentation dependably produces the same aromas that are described on hop packaging.
Doubling Down: When, Why, and How to DDH
Double dry-hopping means different things to different brewers. For some, it means adding hops at both the above times, during fermentation and then again after fermentation. For others it means doing two dry-hop additions at any time. Then there is a literal interpretation that brewers use to indicate this beer is made with twice as many dry hops as other beers of the same style from the same brewery. (For example, the brewery has a hoppy amber ale and a DDH hoppy amber ale.)
If you’re like me, you still have the Zymurgy Magazine article Vinnie Cilurzo wrote about how to brew Pliny the Elder, his double IPA that made the style famous. The recipe is from 2009 and we’ve learned a lot about dry-hopping since then, but he admits to make a “double IPA” he just went ahead and doubled the hops (and pumped up the ABV). This is the spirit many brewers still operate under today.
The term is essentially a signal meaning “this beer is all about hop flavor,” no matter what method the brewer uses. So, if you want to make your homebrew a DDH, just make sure there are a ton of hops (at least 9 or more ounces for a 5-gallon batch) and you’re set.
The Need for Speed
About 48 hours after adding “dry” hops, the aroma compounds of the hop oils will be fully extracted into the beer. Some studies show that maximum extraction can happen as quickly as 24 hours! If the hops sit for more time in the vessel, more polyphenols and other less pleasant compounds can be absorbed. Furthermore, because hop oils (like all oils) are hydrophobic, meaning they do a poor job mixing with water-based solutions, oils in suspension may be repelled back into original hop matter if they rest for too long. It’s better to add a slightly larger quantity of hops and get the beer off of them quickly than it is to count on tiny incremental levels of additional extraction after 48 hours.
On the whole (or better yet, on pellets), dry-hopping is much simpler than marketing mystique makes it seem. It all comes down to three basic decisions: what hop variety you want to use, what form you’ll purchase it in, and if you’ll add it during fermentation or after fermentation. Easy as 1-2-3!