Advanced Dry Hopping Tips, Techniques, & Traps

Dry hopping isn’t just for IPAs anymore! A dose of citrusy, herbal, or tropical hops in the fermenter can be a wonderful addition to West Coast Pilsner, barrel-aged saison, or amber ale. While one approach to dry hopping might work for a hazy IPA, you may want to adjust your process for other styles. You can trade off concentration, temperature, agitation, and time. Higher concentrations, warmer temperature, increased agitation, and extended time all extract more aromatics . . . but also compounds you may not be as excited about like astringent polyphenols, grassy aromatics, and bitter alpha acids. Let’s take a look at how each of those parameters change the finished beer. 

Hop Evaluation

The first and most important step in dry hopping is to evaluate your hops. Whether it’s a new variety or hops you’ve used before, give them a smell! The quick and dirty way is to rub a few pellets between your palms. I find this to be a more “true” representation of what the hop will contribute to the beer compared to smelling the bag. Rubbing also gives you a chance to evaluate the pellets themselves. Denser pellets are more likely to sink and require agitation to suspend them into the beer. Another option is to follow the American Society of Brewing Chemists (ASBC) method of steeping the hops in cool water for 20 minutes in a French press before pressing and smelling, which we previously covered in “Ingredient Sensory Methods” found online here. 

If you don’t like the aroma of the hops, reseal the bag and use them for a whirlpool addition on your next batch. In most cases a little “weirdness” from the hops will blow off with heat or be scrubbed away by fermentation. 

Combining Hops and Beer

There isn’t anything that ruins a good hazy IPA like oxygen exposure. While the deleterious effects may be more subtle in other styles, I treat all of my beers with the same oxygen-phobia. While brewers (rightly) focus on transfers and packaging, one of the most important and treacherous steps is dry hopping. For our first double IPA at Sapwood Cellars I poured the hops into the top of a 10-bbl tank through the “dry hop port.” Within seconds a plume of hoppy foam was shooting at the ceiling (and raining back down onto me). Think 300 gallons (1,100+ L) of Diet Coke and a case of Mentos . . . After that we learned to add a pound or two of hops, close up the tank and allow it to degas. At home it’s rarely so dramatic, but be careful if you are dry hopping a beer that was spunded or fermented under pressure!

We now use a hop doser from MARKS that attaches to the dry hop port, allowing us to purge the hops with CO₂ and then add them to the beer under pressure. Some homebrewers have similar contraptions fashioned from a sightglass and butterfly valve, and they are a great option if you use a conical or a modified keg with a tri-clamp fittings on the lid.

Another great option is to transfer the beer onto the hops. At the brewery we do this in our infusion tank or brinks (both fitted with mesh screens on the outlets to keep the hops in). We add the hops to the empty vessel, purge it with CO₂, and finally fill it with beer under pressure. As a homebrewer, I did this in a Corny keg with the hops in a tube screen. Fill the screen less than halfway to allow room for the hops to expand and extract. Even still, this may reduce aroma extraction — one study found a 50% drop in extraction of linalool from bagging hops.¹ 

If none of these are options with your equipment, dry hop during the tail end of primary fermentation. Active yeast will uptake oxygen quickly and prevent most of the damaging effects of oxidation. Just be warned, active fermentation dry hopping can promote hop creep (discussed later) and will make it more difficult to harvest and reuse the yeast. 

Temperature

According to that same study, extraction of linalool (fruity aromatic) was nearly as rapid at 39 °F (4 °C) as it was at 68 °F (20 °C). The advantage is that colder temperatures reduce the extraction of the harsh/bitter resins and polyphenols. This study was conducted on a small scale. When we tried it on a commercial scale, we found that the cold extraction requires increased agitation to promote contact between the beer and hops. After our first attempt we found whole unextracted pellets at the bottom of the tank.

Colder dry hopping imparts a more “true to pellet” aroma, with fresher, more intense hop aromatics. That said, it can smell like sticking your nose right into a hop bag, rather than highlighting the citrusy and fruity aromatics. This is because warmer mid-to-late fermentation additions lead to a reduction in myrcene (woody/herbal). I prefer colder dry hopping in beers that are drier and less likely to “stand up” to astringency, including most drier or lower-alcohol beers (e.g., West Coast Pilsner, saison, non-alcoholic beers). For hazy IPAs we usually perform one dry hop addition after soft crashing and another close to freezing to get some of each character. Warmer dry hopping also promotes haze formation by releasing more polyphenols to bind with yeast mannoproteins.

Amount of Hops

Higher dry hopping rates result in diminishing returns. A beer dry hopped with 1 oz. per gallon (7.5 g/L) isn’t twice as aromatic as one with 0.5 oz./gallon (3.8 g/L). That is because it is more difficult to fully extract a larger dose of hops, some compounds saturate, and the green material of the hops reabsorbs compounds already in solution. 

To deal with the extraction issue, you can add dry hops in multiple stages. However, if you don’t have a way to remove the spent hops and introduce another dose without oxygen ingress you may be better off with a single dose. My preference as a homebrewer was to add half of the hops loose to primary and the rest to the keg in a weighted metal tube screen. The hops in primary settle out with the yeast, while the tube screen reduces issues with clogged poppets (at the expense of lower extraction). 

For the absorption issue, advanced hop products can help. I often like to replace 25–50% of the traditional T90 pellets with concentrated/lupulin “enriched” pellets like Cryo Hops^®, T45, CGX^TM, and LupoMax^®. Generally, we use traditional pellets for the first dose and concentrated for the second. Concentrated pellets tend to be higher in oil and more finely ground, and as a result stay in suspension longer even at colder temperatures.

If that doesn’t get you the intensity you are looking for, then hop extracts, oils, and terpenes like Yakima Chief Hyperboost^TM, Abstrax Quantum Brite, and Spectrum from BarthHaas are a great final addition. These are ideal because they can be dosed to taste, even in the glass (an easy way to make hop water if you have a keg of seltzer). While they are often sold for breweries looking to maximize yield by reducing reliance on hop pellets, none of them can completely replace dry hopping. IPAs without actual hops just don’t have the right mouthfeel or breadth of hop flavor and aroma. To my nose they tend to “brighten” the aroma, covering up dull aromatics with more fruitiness. 

Replacing some hop pellets with oils can also lead to a more durable hop aroma. Hops include a variety of compounds that can accelerate staling (e.g., metal ions). Hops can also have air trapped inside the pellets. Adding oils reduces these risks and creates a beer that still smells “hoppy” well after a heavily dry-hopped beer would fade. Extract companies have suggested to me that 2 lbs./bbl (1 oz. per gallon/7.5 g/L) is around the sweet spot for saturating the beer with a variety of hop compounds, and then topping up with oil; though we still most often add 4–5 lbs./bbl (2–2.5 oz./gallon or 15–19 g/L) for IPAs and double IPAs, and I can taste the difference. 

Agitation

There are many options for agitation: Dissolved carbonation in the beer, physical agitation of the fermenter, rousing with CO₂, recirculating pumps . . . I’ve even attached a Mighty Dwarf speaker onto a fermenter, which generates sound by vibrating the object it is placed on! I hooked it up to a tone generator and adjusted the frequency until it created a resonance with the beer.

The most traditional method is to simply allow the trapped carbon dioxide in the beer and produced during the tail end of fermentation to agitate the hops. The risk here is that the CO₂ exiting the beer can scrub out delicate hop aromatics and the yeast can pull some of them out of suspension. That said, the more fragile aromatics tend to be “green” like myrcene, and as a result less desirable in many styles. While I had decent results as a homebrewer with mid-fermentation dry hopping, it never seemed to work for us on a commercial scale. The aroma just never popped, and if we tried to agitate the hops we’d get harsh astringency. These days we rely on whirlpool hops and flowable CO₂ extracts (Incognito^®, DynaBoost^TM, or TerpSauce^®) for “saturated” fruity hop flavor.

As a homebrewer, I would wait a few hours for the tail end of fermentation to purge out the fermenter’s head space after dry hopping. Then I’d rock the closed fermenter to increase contact and resuspend the hops. With 620-gallon (2,350-L) tanks that isn’t an option, so at Sapwood Cellars we use a high-flow CO₂  regulator to bubble CO₂ through the beer for 1–2 minutes several times. I’ve talked to other brewers who will pressurize a piece of hose to send one large “blast” of CO₂ through their beer. 

As tanks become even larger, the only option is to recirculate the beer with a diaphragm pump to keep the hops in suspension. Impeller pumps can pull in air if the seal leaks and can increase astringency by beating up the leaf material. Peter Wolfe’s thesis “A study of factors affecting the extraction of flavor when dry hopping beer” found most hop aromatics peaked between 6–24 hours at room temperature.² This was on a small scale with a relatively low dry hopping rate. Mitch Steele (New Realm Brewing Co.) suggests that anecdotally, he has achieved the best results with “periodic” agitation over the first 48 hours after dry hopping.

If you have an opaque fermenter, pull a sample after rousing to check that the hops are in suspension. Check again in an hour or two to see how well they are staying in suspension to determine how frequently you need to rouse. 

Exposure Time

Traditionally, English brewers dry hopped in the cask until the beer was consumed. Most American brewers now prefer one to three days (although I’ve heard as long as seven). Again though, that really comes down to time, temperature, and agitation. Taste the beer each day and consider stopping your agitation or crash chilling if you’ve achieved the aroma you are looking for or you’re worried about extracting more astringency or vegetal aromatics. Both of these can be difficult to judge on a flat sample, but you’ll learn by tasting and taking notes.

Hop Creep, Diacetyl, ALDC, and GM Yeast

Hops contain amylase enzymes that turn unfermentable dextrins in the beer into fermentable sugars.³ If you are dry hopping warm with active yeast it could happen to you. Zach Bodah of Allagash is credited with investigating this and drawing attention to hop creep in 2017 after a dry-hopped beer over-carbonated during bottle conditioning.⁴ 

In addition to lowering the final gravity slightly, this renewed fermentation can lead to diacetyl (buttery off-flavor). Bob Kunz from Highland Park (Los Angeles, California) suggested we add Alpha Acetolactate Decarboxylase (ALDC) enzyme to a warm dry-hopped West Coast Pilsner we brewed in collaboration with him. ALDC prevents diacetyl production by “skipping” a step and using up the precursor (alpha acetolactate) by converting it to acetoin. As a result, it has to be added at the same time or before the dry hops, as it isn’t effective at removing diacetyl once it is created. Another option is to ferment with a brewing yeast that has been genetically modified to not produce diacetyl (sugh as Omega Yeast’s “Plus” series of strains). 

Hop creep is not a new concept. Gareth Young from Epochal Barrel Fermented Ales in Glasgow, Scotland, showed me a 19th century Scottish brewing textbook that spelled out the exact same issues. Gareth uses the technique at his brewery intentionally to create uniquely delicious mixed-fermentation beers, allowing the enzymes from the whole hops in the barrels to free sugars for an extended mixed fermentation while the hop aromatics interact with the Brettanomyces.

At Sapwood Cellars, dry hopping cold after dropping out the yeast has prevented hop creep . . . but then we store our beer cold after packaging and don’t send much beer out to distribution. As a homebrewer, you can do the same.

Evaluating the Results

IBUs
For a recent triple IPA we targeted 40 IBUs/ppm of isomerized alpha acids in the kettle. That drops considerably through fermentation, and absorption by the green material in dry hops. After dry hopping we sent a sample to Hopsteiner for analysis with HPLC (High-Performance Liquid Chromatography). The result was only 7 ppm of iso-alpha in the finished beer. However, all of the additional hop compounds from the dry hopping added 90 IBUs. The problem is that while alpha acid, humulinones, and xanithohumol are detected as IBUs with the traditional tests looking at light absorbance at 275 nm, they don’t taste as bitter as iso-alpha — that puts the approximate bitterness perception at 27.9 IBUs. All that is to say, it’s easier to talk about the perceived bitterness than the actual “number” of IBUs (especially because residual sweetness, polyphenols, alcohol, and other factors affect how bitter a beer tastes).

pH
Dry hopping raises the pH of the beer. Our solution is to acidify with phosphoric acid in the kettle into the high-4s at the start of the boil. This has the added benefit of lowering the rate of Maillard reactions in the kettle, producing a paler, less “malty” wort. Be warned though, it also lowers alpha acid isomerization (~10% fewer IBUs at a pH of 4.8 compared to 5.2 in one study.⁵ Fermentation drops that pH further into the low-4s. Dry hopping generally raises the pH back to 4.5 or so. That works for us — and helps promote beer stability — but in the end I’d be more concerned about how the beer tastes to you. A little lower pH can help a double IPA read crisper and more drinkable, while a higher pH can cause a pale ale to read richer and fuller. 

Sensory
One of the most important things you can do to improve your beer is to drink it critically and evaluate the results. Whenever I can, I sit down with our freshest batch next to something similar from another brewery. I try to be analytical, noticing trends (are my beers always more astringent, or contain a certain aromatic?). Do I notice a particular note from one of the hops that carried through, or are there aromatics that were lost? Almost as important is the hedonistic “enjoyment” (which beer do I find myself going back for another sip of?).

Tips and Tricks

For a long time, I underappreciated how much the right yeast strain could enhance hop aroma. Don’t be afraid to think like a Belgian when it comes to maximizing yeast character. Consider warmer fermentations, manipulating pitching and aeration rates, and blending yeast strains! Pair a hop variety with a complementary yeast strain. Here are some examples: 

• Cosmic Punch with Galaxy^® (passion fruit)

• Conan with Amarillo^® (stone fruit)

• London with Strata^® (grapefruit)

• Sacch Trois with Citra^® (orange)

• Hefeweizen with Cashmere (banana)

• Belgian with Krush^TM (bubblegum)

Don’t confuse adding more hop varieties with increasing complexity. Most hops contain the same set of aromatics in different ratios. Blending four or five varieties often creates an “average” hop aroma. That’s great if you are a big brewery trying to make a consistent core beer, but not if you want something unique and varietal. Stick to dry hopping with no more than three varieties in a single beer unless you really have something specific in mind. 

Hoppy Time

It’s easy to forget that homebrewed dry-hopped beers start with a huge built-in advantage — freshness! I get to go to Yakima to select hops each fall, have all the equipment and gizmos, and package beers with <30 ppb total package oxygen (TPO), but if that can sits warm for a month it loses that amazing “fresh” hop aroma! Like home cooking, homebrewers also have the advantage of using the ingredients and process that create your ideal beer without worrying about sales, marketing, or consistency! 

References:
¹ Mitter, W. and Cocuzza, S. (2013) “Dry Hopping — A Study of Various Parameters,” Brewing and Beverage Industry International, March, pp. 70–74. www.shorturl.at/CwWEF

² Wolfe, P. (2012) “A study of factors affecting the extraction of flavor when dry hopping beer.” www.shorturl.at/QeiCt

³ Young J, Oakley WRM, Fox G. (2023) “Humulus lupulus and microbes: Exploring biotic causes for hop creep.” Food Microbiol. www.shorturl.at/4LVhY

⁴ Hieronymus, S. (2020) “Brewing with Hops: Don’t be Creeped Out,” Craft Beer & Brewing, October.  www.shorturl.at/FhYn3

⁵ Jaskula B, Aerts G, De Cooman L (2010) “Potential impact of medium characteristics on the isomerisation of hop α-acids in wort and buffer model systems. Food Chem. Vol. 123, Issue 4, pages 1219-1226. www.shorturl.at/TTjLM

Written by Michael Tonsmeire