Article

Dip Hopping

Modern beer consumers have an insatiable desire for hops. A simple listing of certain varieties on a beer label will send buyers into a tizzy. Hop growers are ramping up programs to develop new varietals that bring exciting flavors and aromas to the forefront. And brewers are working behind the scenes to find new ways to work with hops that not only slake drinker’s desires, but also make the most of the remarkable little flower that is fueling the industry.

In 2012 Kirin, the Japanese brewing conglomerate, began talking about “dip hopping,” a technique that its brewers had developed that boosts pleasant hop aromas while suppressing or removing unpleasant off-flavors, like myrcene, and aromas that are derived from fermentation. 

The method was used in a number of the brewery’s beers, including the Grand Kirin beers, but received little attention in the larger beer world, especially as a younger generation of brewers were largely focused on giving a never-ending bear hug to the double dry-hopped method. 

Over time, however, conversations were had, stories were shared, studies were conducted, and a game of hoppy telephone began to spread across the globe as brewers worked to unravel and advance dip hopping.

On what they expected to be a short and rather perfunctory visit to Spring Valley Brewery in Japan seven years ago has turned into a growing network of brewers across the U.S. who are experimenting with dip hopping. 

Van Havig and Ben Love of Gigantic Brewing in Portland, Oregon were visiting key accounts in Tokyo when they stopped by Spring Valley, the craft brewery owned and operated by Kirin. While tasting through some beers, they both were stopped dead in their tracks by “496,” a pale ale that revealed a wonderful hop character. 

Havig recalls a conversation with a brewer at Spring Valley and asked about the hops used. The answer surprised, delighted, and confused him. 

“I said there was no way the hop was Apollo,” recalled Havig. He asked how the flavors were possible through Apollo, and the brewer responded: Dip hopping. 

If the second half of the last decade was dominated by brewers embracing double dry hopping (DDH), there remains the possibility that the future of extracting desired hop flavor in a relatively straightforward way, could be
dip hopping. 

After being introduced to dip hopping, the brewers of Gigantic slowly started sharing their newfound information with other brewers. Around the same time, the John I. Haas company ran a blurb in its February 2019 newsletter summing up dip hopping this way: “Dip hopping means the addition of hop after wort cooling before (the) start of fermentation.” They note that with this hopping technology Spring Valley “found the following results: Hop enzymes do not contribute to main fermentation, myrcene levels in finished beers are very low, which was found favorable in this case. Also, the production of 2M3MB an onion type of flavor (derived from iso-alpha acid) is suppressed due to a lower H2S content in the beer.”

In 2018, brewers from Kirin presented their findings at an American Society of Brewing Chemists conference that further dove into the science:

“2-Mercapto-3-methyl-1-butanol (2M3MB) imparts an onion-like off-flavor to beer. In a previous study, we purified the precursor of 2M3MB from hops and identified it as 2,3-epoxy-3-methyl-butanal (EMB),” the brewers of Asahi wrote. “We found that during the hot aeration of wort, which has long been considered as the cause of the onion-like off-flavor, the amount of EMB in wort increases with the oxidation of iso-alpha-acids.”

When it comes to dip hopping, just think of it as a different type of steeping or an infusion of hops and wort prior to yeast fermentation or prior to yeast being in the beer. 

While the Spring Valley brewers wouldn’t fully reveal their process to Havig and Love at the time, over drinks at Spring Valley, Havig was able to ask a series of questions that gave him the framework for the dip hopping process that has now been passed along to other breweries that have experimented with it in their own ways. 

Havig says the current methodology at Gigantic is to use about a half a barrel of hot liquor for every 11 pounds of hops. They sanitize a fermenter, add the hops “and then we’ll just pump the water in there at around 170 °F (77 °C) and let it sit for an hour and then we just knock out on top of it at totally normal temperatures; whatever is normal for whatever we’re brewing.”

So far Gigantic has used this process mostly with ales but did a collaboration lager with Magic Rock in the United Kingdom using the process. Kirin/Spring Valley created dip hopping, but conversations with breweries lead back to Gigantic for introducing it to the United States. 

Niko Tonks, of Fair State Brewing Cooperative in Minneapolis says his brewery first made a dip hopped beer as a collaboration with Three Floyds of Munster, Indiana. Jerrod Johnson, of Fair State had worked at Surly with Todd Haug, who is now at Three Floyds. Before that, however Johnson worked with Havig. 

See how this works? 

Tonks said the beer they made was a success, wonderfully aromatic, a throwback to West Coast IPA, but without some of the pungent onion and garlic aromas. Different from Gigantic’s approach where water is used with the dip hops in the fermenter, Fair State brewers pulled about 10% of the wort from the boil, chilled it down to 170 °F (77 °C), and transferred it to the fermenter to create a hop tea. By the end of the boil the rest of the cooled wort was added about an hour later. While the reported results for Fair State have been positive, the technique is not one that the brewery could do with any regularity. 

“Especially not on a large scale because the big downside is just that it renders the yeast from that beer unusable. We’re essentially fermenting on a whole bunch of hop pellets and so it’s just a big morass of goo at the bottom of the tank. When you’re done you can’t really crop it and so for that reason it’s a difficult technique to actually mainstream into your production,” he says. 

Hops are loaded into the fermenter prior to running wort or water on top of them to create a hop tea. An hour later, the remaining wort is chilled and added to the fermenter and yeast is pitched as usual.

Though for brewers that are used to DDH ales and pitching a new yeast every brew day — as many homebrewers do — this process might be easier, he notes. Tonks says his brewery is interested in doing more of these beers, but for now, they are best suited for special occasions, like collaborations, given their production schedule. 

Head north, however, to Fargo, North Dakota and you find Mark Bjornstad, the founder of Drekker Brewery, who happened to be at Fair State on the day of the Three Floyds collaboration. He would later do his own dip-hopped beer with Fair State, and since then has been experimenting in his brewery with different hop varietals and temperatures to achieve new flavors and aromas that are bringing great depth to his hoppy ales. 

In describing his brewery’s process, Bjornstad cited similar methods and temperatures to what Gigantic has done in the past, but as he has been messing around with hot liquor and hop ratios he has been playing in the 160–170 °F (71–77 °C) range with about an hour of steeping. For now, they are going on sensory rather than scientific analysis, he says. 

“We’re kind of practicing like the dark arts of this stuff, going blind based off the little bit of research that has been done. We look at this as a way to really mess with the precursor chemicals, the hop oils, and the hydrocarbons,” he says. 

This is where the brewers seem to be most excited about dip hopping and its ability to extend beyond the brewhouse, and to hop selection. 

Bjornstad says the “time, temperature, and concentration” are the three pillars they are experimenting with. So far, he has played with various ratios over a dozen or so brew days. 

“We’re looking at the time of wort and hop interaction prior to yeast so we give it an hour, or four hours, or 30 minutes,” he says. “The volume of wort is sometimes 15 percent of the whole batch, sometimes it’s the whole batch. Sometimes we’re doing it at 175 °F, 160 °F, 140 °F (79 °C, 71 °C, 60 °C). You can do it at 100 °F, or 70 °F (38 °C, or 22 °C). That’s where we’ve been playing around and there are crazy variables and we’re trying to figure out which hops work best in different scenarios.”

Regardless of temperature, Bjornstad says that when they pump hot liquor and hops into a fermentation vessel and seal the tank, even for an hour, pressure builds inside and the aromas coming from the blowoff tube are strong of fresh cut grass. 

“That’s just pure myrcene and it’s exciting because when you taste the wort right after it’s totally different than what was in the knockout, so it opens our mind to what hops we can use or want to use,” he says. 

The brewery has been thinking about “less popular” hops that could benefit from this treatment to reveal new depths of flavor after the myrcene is gassed off. He cites Nugget as a good example. 

“It has some great oil contents but previously had a ratio that was just going to ruin the kind of beer we’re looking to make. But now we have a different way to modulate the hops, to tweak and dial up or down some of the desirable or undesirable flavor compounds and ac-
tive compounds.” 

He points to hops that have good amounts of citronelle or similar compounds but also have high myrcene contents as the best candidates. Without dip hopping you’re never going to get away from the greenness that myrcene brings to a beer, he says, but with higher temperature dip hopping you can start to taste flavors like rosebud and all these other aromas below it that otherwise wouldn’t be tasted.

Bjornstad and other brewers see a net positive in biotransformation as well when it comes to dip hopping. The process allows brewers to examine the yeast they plan to use for a particular recipe that can create new and different flavors. Dependent on the temperature, once you gas off the myrcene, which can be a precursor to linalool, and it can be a precursor in biotransformation.

“In these higher temperature dip-hopping trials we’re seeing the conversion of myrcene into linalool or geraniol and that has flavor implication on the beer for producing different flavors that would otherwise not be tasted.”

During the 2018 Brewing Summit, held in San Diego, brewers Yuri Tsuchiya, Taku Ota, Hiroyuki Yoshimoto, Osamu Kobayashi, and Hironori Inadome of Kirin presented their findings on the “Effect of hops addition to the fermentation tank on beer fermentation” where they examined the “phenomenon” known as dip hop. 

“Fermentation was conducted with and without dip hopping. Dip hopping increased the sugar consumption rate and the number of yeast cells, compared with no dip hopping. Similar results were obtained by adding activated charcoal to the wort,” they found. 

The brewers also found that the formation of hydrogen sulfide (H2S) was key in the formation of 2M3MB in beer and that dip hopping was a potential solution. One hypothesis of theirs was: “Metabolome analysis revealed that in sulfur metabolism, intracellular threonine is more easily consumed by dip hopping, resulting in increased levels of O-acetyl homoserine (OAH). By increasing OAH, the pathway from H2S to homocysteine is activated and H2S production decreases.”

It’s the exploration of well-established hops that have presented overly green flavors and aromas in the past that makes for a new “arrow in the quiver” when brewing, says Havig. The emergence of underlying flavors that had been blocked by myrcene in the past will open up new opportunities for brewers and drinkers. 

Knowledge of and the embrace of dip hopping also can be helpful for brewers during the annual hop selection, says Tonks. Lots that might not otherwise have been a first, second, or third choice for brewers are now in play as breweries can look past initial aromas and see the potential in underlying flavors. 

Will this method catch on by more breweries in the coming years? 

“I think it has potential especially for people who are using it as a targeted tool to really try to achieve specific ends as opposed to just looking for another way to cram more hops into a beer,” says Tonks.

Dip-Hopped Recipes

Fair State Brewing Cooperative & Arbeiter Brewing Co.’s Bibbidy Drippidy Hop clone

(5 gallons/19 L, all-grain) 
OG = 1.059  FG = 1.010
IBU = 59  SRM = 4  ABV = 6.6%

Some may call this recipe a “zero IBU IPA” as no hops are added in the boil.
Of course, whirlpool and dip hop additions will contribute both bitterness
and IBUs when measured using a
spectrophotometer.

Ingredients
8.5 lbs. (3.9 kg) Rahr North Star PilsTM malt
3 lbs. (1.4 kg) Rahr white wheat malt
1.25 lbs. (0.57 kg) Simpsons malted oats
1 lb. (0.45 kg) rice hulls
3 oz. (85 g) Strata® hops (0 min.) 
3 oz. (85 g) Strata® hops (dip hop) 
2 oz. (57 g) Mosaic® Cryo hops (dry hop 1)
2 oz. (57 g) Citra® Cryo hops (dry hop 1)
3 oz. (85 g) Strata® hops (dry hop 2)
1⁄2 tsp. yeast nutrient (10 min.)
White Labs WLP013 (London Ale) or Wyeast 1028 (London Ale) or
SafAle S-04 yeast
3⁄4 cup corn sugar (if priming)

Step by Step
Mill the grains and dough-in targeting a mash of around 1.25 quarts of water to 1 pound of grain (2.6 L/kg) and a mash temperature of 150 °F (66 °C). While waiting for the run-off and boil to begin add 3 oz. (85 g) of Strata® “dip hops” directly to a clean, sanitized fermenter.

Total boil time is 60 minutes. No hops will be added until post-boil. With 30 minutes left in the boil, run un-hopped wort to the fermentation vessel with the Strata® hops at 170 °F (77 °C) until the hops are aggressively submerged (~0.5–1 gallon/2–4 L). Seal the fermenter with an airlock as soon as possible. Continue to boil the remaining wort. At 60 minutes turn off the heat and pitch your flameout addition and whirlpool for 20 minutes. 

Chill the wort to lower than the target fermentation temperature. Once all the wort is in the fermenter, adjust the wort volume as needed to 5.5 gallons (21 L) and the wort temperature to 68 °F (20 °C), then aerate thoroughly and pitch yeast. Pitch rate is 1,000,000 cells per mL per degree Plato. Ferment at this temperature.

Track the gravity daily and at approximately 1.018 specific gravity dry hop with 2 oz. (57 g) each Mosaic® Cryo pellets and Citra® Cryo pellets.

Forty-eight hours later add 3 oz. (85 g) Strata® as the second dry hop. Track gravity until the beer is at terminal gravity. Chill the beer and carbonate the beer to around 2.5 volumes of CO2.

Fair State Brewing Cooperative & Arbeiter Brewing Co.’s Bibbidy Drippidy Hop clone

(5 gallons/19 L, partial mash) 
OG = 1.059  FG = 1.010
IBU = 59  SRM = 4  ABV = 6.6%

Ingredients
5 lbs. (2.3 kg) Pilsen dried malt extract
1 lbs. (0.45 kg) wheat dried malt extract
1.25 lbs. (0.57 kg) Rahr white wheat malt
1.25 lbs. (0.57 kg) Simpsons malted oats
3 oz. (85 g) Strata® hops (0 min.) 
3 oz. (85 g) Strata® hops (dip hop) 
2 oz. (57 g) Mosaic® Cryo hops (dry hop 1)
2 oz. (57 g) Citra® Cryo hops (dry hop 1)
3 oz. (85 g) Strata® hops (dry hop 2)
1⁄2 tsp. yeast nutrient (10 min.)
White Labs WLP013 (London Ale) or Wyeast 1028 (London Ale) or
SafAle S-04 yeast
3⁄4 cup corn sugar (if priming)

Step by Step
Heat one gallon (3.8 L) of water in a large stockpot. Crush the grains and place in a large muslin bag. When water reaches 162 °F (72 °C), submerge the grains and stir to make sure there are no dough balls. The mash temperature should stabilize around 150 °F (66 °C). Try to maintain this temperature if possible. After 60 minutes, remove the grain bag and place in a large colander. Wash the grains with 1 gallon (3.8 L) of hot water, collecting the runoff. If you can, bring the volume up to 5 gallons (19 L) and add the dried malt extract off heat. Stir until completely dissolved then turn on heat and bring wort to a boil. Add 3 oz. (85 g) of Strata® “dip hops” directly to a clean, sanitized fermentation vessel. 

Follow the remainder of the instructions in the all-grain recipe. 

For more details about this collaboration between Fair State and Arbeiter, as well as discussion about dip hopping, check out this link to a recent episode of Chop & Brew in which brewers Nick Walby (Fair State) and Aaron Herman (Arbeiter) discuss their experiences from the brew day: http://bit.ly/diphopvideo

Gigantic Brewing Co.’s Belmont Boogaloo clone

(5 gallons/19 L, all-grain)
OG = 1.051  FG = 1.008
IBU = 12  SRM = 9  ABV = 5.6%

“This beer dates from 2017 — it has nothing to do with any current extremist groups. It is a reference to Breakin’ Two: Electric Boogaloo. It was both our second beer made specifically for them, as well as their 20th anniversary, so a repeat theme made sense. But this is really the only packaged beer that we’ve dip hopped extensively. We tend to ‘bring it’ to other breweries more often than use it ourselves, or we use it as just a small part of a larger hopping procedure. This is pure dip hop.”
– Van Havig, Master Brewer, Gigantic Brewing Company

Ingredients
9.8 lbs. (4.5 kg) Mecca Grade Lamonta pale malt (Maris Otter or other)
6 oz. (170 g) Simpsons medium crystal malt (65 °L)
0.8 AAU Nugget hops (90 min.) (0.07 oz./2 g at 12% alpha acids)
10.7 AAU Crystal hops (5 min.) (2.7 oz./75 g at 4% alpha acids)
1.8 oz. (51 g) Mosaic® hops (dip hop)
1.8 oz. (51 g) Simcoe® hops (dip hop)
1.8 oz. (51 g) Citra® hops (dip hop)
Wyeast 1728 (Scottish Ale), White Labs WLP028 (Edinburgh Scottish Ale), Imperial Yeast A31 (Tartan Ale), or LalBrew Nottingham Ale yeast
3⁄4 cup corn sugar (if priming)

Step by Step
This is a single step infusion mash at 150 °F (66 °C). Hold at this temperature for 90 minutes before lautering. Collect roughly 6.5 gallons (25.6 L) of wort in your boil kettle. This is a 90-minute boil, adding your first hop addition at the start of the boil. 

About one hour before cooling the wort, add the dip hops to a clean and sanitized fermenter. Add about 1.5 qts. (1.5 L) of water at 175–185 °F (80–85 °C). Pellets should be cold — the hop and water solution will come down to 140 °F (60 °C) or so. Don’t worry about it too much. If you used hot enough water, it will be “hot enough.”

When boil is complete, cool wort and add to the fermenter. You should be adding about 5 gallons (19 L) into the dip-hop solution already in the fermenter. Aim for a fermentation temperature of 72 °F (22 °C); when these strains are fermented warm, they can be quite estery.

Van Havig recommends that brewers remove the yeast from the beer after conditioning. “We fine our beers the old fashioned way with isinglass — because technology isn’t always the answer,” he said.

Gigantic Brewing Co.’s Belmont Boogaloo clone

(5 gallons/19 L, extract with grains)
OG = 1.051  FG = 1.008
IBU = 12  SRM = 9  ABV = 5.6%

Ingredients
6.6 lbs. (3 kg) Maris Otter liquid malt extract
6 oz. (170 g) Simpsons medium crystal malt (65 °L)
0.8 AAU Nugget hops (90 min.) (0.07 oz./2 g at 12% alpha acids)
10.7 AAU Crystal hops (5 min.) (2.7 oz./75 g at 4% alpha acids)
1.8 oz. (51 g) Mosaic® hops (dip hop)
1.8 oz. (51 g) Simcoe® hops (dip hop)
1.8 oz. (51 g) Citra® hops (dip hop)
Wyeast 1728 (Scottish Ale), White Labs WLP028 (Edinburgh Scottish Ale), Imperial Yeast A31 (Tartan Ale), or LalBrew Nottingham Ale yeast
3⁄4 cup corn sugar (if priming)

Step by Step
Place the crushed grains in a muslin bag and steep in roughly 6.5 gallons (25.6 L) of water as it heats up. Remove grains when the temperature reaches 165 °F (74 °C). Turn the heat off and stir in the liquid malt extract. Once all the extract has dissolved, turn the heat back on and bring up to a boil. This is a 90-minute boil, adding your first hop addition at the start of the boil. 

About one hour before cooling the wort, add the dip hops to a clean and sanitized fermenter. Add about 1.5 qts. (1.5 L) of water at 175–185 °F (80–85 °C). Pellets should be cold — the hop and water solution will come down to 140 °F (60 °C) or so. Don’t worry about it too much. If you used hot enough water, it will be “hot enough.”

Add cooled wort to solution in fermenter. You should be adding about 5 gallons (19 L) into the dip-hop solution already in the fermenter. Aim for a fermentation temperature of 72 °F (22 °C); when these strains are fermented warm, they can be quite estery.

Van Havig recommends that brewers remove the yeast from the beer
after conditioning, which Gigantic does by using isinglass. 

Issue: May-June 2021