Hops are added at different stages during the brew day to achieve different effects. Most homebrew recipes will indicate when to add the hops: early for bittering, mid to late for flavor, and at the end of the boil and in the fermenter for aroma. Bittering hops are added when the wort is first collected in the brewpot, either just before the boil (first wort hopping) or when it starts to boil. Flavor hops are typically added when there are 15 to 30 minutes left in the boil, which will provide some additional bitterness, but the hops will not boil long enough to allow the heat to drive off the hop flavor. Finally, aroma hops are added either at the end of the boil, at “flame out” (when the heat is turned off), in the whirlpool, or in the fermenter as dry hops.
First Wort Hopping
As far as adjusting a brew day technique, it really doesn’t get any easier than trying first wort hopping (FWH). While there is still some ambiguity that surrounds its overall affect on the finished beer, most brewers will either use it as a substitute for their bittering hop charge or their mid-boil hop charge. So why the ambiguity? It has been shown in tastings that FWH can increase the perceived aroma of a beer when substituted for a traditional late hop addition to the kettle. Yet when a group of scientists tested the hop aroma components of FWH beers, they found that the aroma compounds were actually considerably lower in FWH beers versus the same beer with that late hop addition. So let’s delve into FWH to find out more.
FWH is very simple: add a portion or all of your late boil hop charge or bittering hops before the wort comes to a boil. It does not matter whether you are an all-grain or extract brewer. Generally as an all-grain brewer you’d do this about 3 to 5 minutes into the sparging process of the grain bed. When you’re using extracts, you’d generally wait until the wort has gotten up to about 180°F (82°C) before tossing the FWH into the kettle.
So what does FWH do for your beer? What repeated studies have shown from blind triangle taste tests is that it creates a softer, more rounded bitterness than adding your bittering hops to a rolling boil. Two studies in particular document this effect. The first is a fairly comprehensive study put out back in 1995 by a German group of researchers, Preis, Nuremberg, Mitter, and Steiner titled, “The Rediscovery of First Wort Hopping,” published by Brauwelt International. The second study was performed by US homebrew guru Denny Conn, whose results roughly affirmed that of the German researchers, and he presented his findings at the 2008 National Homebrewers Conference.
The German researchers utilized two breweries to test FWH versus a late hop addition. The taste tests from both breweries confirmed that there is a distinct difference between a beer with first wort hopped charge and bittering charge and beers brewed with a traditional bittering charge and late hop charge. Among those on the panel, twenty-one out of twenty-three tasters were able to recognize the taste discrepancy in a Pilsner. Of those twenty-one tasters who distinguished some difference between the two beers, nineteen of them preferred the first wort hopped beer. Denny Conn’s study, which was performed with two groups of BJCP judges and professional brewers, tested FWH beers versus a traditional bittering charge. What they found in a blind triangle test was that seven of the eighteen tasters were able to distinguish the first wort hopped beer—still significant but not quite as striking as the German study. The general consensus among those who could distinguish among the two beer types was that the first wort hopped beer offered a smoother bittering profile than the reference beer.
The other aspect that the two studies confirmed is that first wort hopping will increase your bittering units without increasing the perceived bitterness. The IBUs of a beer that has been first wort hopped achieve on average about 10 percent more hop utilization when analyzed against the same beer with a standard 60-minute hop addition. The Germans found in the first Pilsner with FWH 39.6 IBUs, compared to 37.9 IBUs for the reference beer. The second Pilsner was found to have 32.8 IBUs, and the reference beer had 27.2 IBUs. Denny Conn’s beers, when analyzed, had 24.8 IBUs for the FWH beer and 21.8 IBUs for the reference beer. The German study also showed that the iso-alpha acid concentration was quite a bit higher for the FWH beers. But again, taste tests revealed that the actual perception of the bitterness levels are slightly lower for the FWH beers. In other words, they had less bite.
So when is it advisable to utilize the FWH technique? It’s up to your personal preference, but some styles that are a good fit for a trial are malt forward ales and lagers or well-rounded styles such as continental lagers, roasted grain-focused beers, wheat beers, and Scottish ales. On the other hand, you may want to skip FWH and stick to a more traditional hopping schedule when you’re looking for more bite in the beer, such as with American IPAs, double IPAs, robust porters, or imperial stouts. Of course, you could also try splitting the bittering hops so that half go in at first wort and the second half go in with 60 minutes left in the boil.
Note: Mash hopping is another pre-boil hopping technique, but it is not one used by many brewers. Unlike FWH, iso-alpha acid conversion does not take place at an appreciable level at mash temperatures, so alpha acids do not undergo the isomerization reaction. Furthermore, the oils that are extracted from the hops will most all be driven off during the boil.
Hop Stands, Whirlpool Hopping, and Hop Bursting
A hop stand is simply allowing boiled wort an extended contact period with the flameout hops prior to chilling. Pro brewers typically create a whirlpool either in their kettle or in a separate whirlpool vessel with the hot wort and the ensuing vortex creates a cone-shaped pile in the center of the vessel made up of the unwanted trub and leftover hop material, hence many pro breweries will refer to this technique as whirlpool hopping. (As a homebrewer working with a much smaller volume, it’s not necessary to keep the wort constantly swirling in the kettle for this technique to work, though.)
Whirlpool hopping is a great way to add unique hop aroma and flavor to your beer.
Another slight variation on this technique is adding all of your boil’s hop additions—including the hops for bittering—at this point. This is known among homebrewers as hop bursting.
In short, all of these techniques allow the hops added at flameout a period to release their essential oils into the wort, while minimizing the vaporization of these essential oils. In essence, it adds a kick of hop flavor and aroma while also adding what can best be described as a smooth bitterness. Read on to find out more about how these techniques can add significantly to the hop flavor and aroma of beer.
A Word on Essential Oils
The essential oils found in hops are volatile and provide beer with the hop flavor and aroma hop aficionados enjoy. While there are hundreds of essential oil components, for practical purposes brewers tend to focus on four to eight main essential oils that play vital roles in providing hop varietal characteristics. One important characteristic is the essential oil’s flashpoint, or the temperature at which the essential oil is actively vaporizing to the point where it could ignite if sufficient vapors were present. At wort boiling temperatures, all hop essential oils have surpassed their flashpoints, so a vigorous boil will drive them off fairly quickly.
The best way to think about the driving off process is in terms of half lives. The lower the flashpoint, the faster the oil vaporizes and the faster the half life. The longer the hops are boiled and the lower the flashpoint, the less the essential oil will impact the beer. In effect, whirlpool hopping removes the rolling boil (for the whirlpool hops), lowering the temperature of the wort and therefore reducing the vaporization rate of the essential oils, allowing the essential oils to really soak in to the wort.
Alpha Acid Isomerization
Alpha acids will continue to isomerize after flameout until the temperature of the wort reaches about 175°F (79°C). Homebrewers trying to calculate a beer’s IBUs will need to guesstimate how much isomerization is occurring. The closer the wort is to 212°F (100°C), the higher the alpha acid isomerization rate. To do this, we can look to professional brewers for some guidelines. Ultimately, however, the thermal capacity of a professional 60 bbl whirlpool vessel is quite different than 5 gallons (19 L) of homebrew, so the comparisons can only be rough guidelines at best.
Matt Brynildson of Firestone Walker Brewing Company says, “The fact that there is some isomerization [about 15 percent in whirlpool versus 35 percent in the kettle] of alpha acid means that not only hop aroma and hop flavor can be achieved, but also some bittering.”
For Pelican Pub & Brewery’s Kiwanda Cream Ale, brewmaster Darron Welch adds the beer’s only hop addition at flameout. Welch gets about 25 IBUs from adding roughly 0.75 pounds/bbl (0.34 kg/bbl) of Mount Hood hops at flameout, then allowing a 30-minute whirlpool stage. This means that Darron is getting roughly 16 percent utilization on his 15 bbl system for a 1.049 specific gravity wort. As mentioned, in a homebrewers hop stand, the 5-gallon (19-L) kettle is going to cool much faster and therefore create lower utilization rates. Brad Smith, creator of the BeerSmith brewing calculator, gives this advice to homebrewers, “Something in the 10 percent range is not a bad estimate if hops are added near boiling and left in during the cool-down period.” In BYO’s testing of extended hop stands in 11-gallon (42 L) batches, a 10 percent utilization rate for whirlpool hops seems reasonable.
Giving It a Try
While hop-forward beers can benefit from this technique, any beer where some hop nose is desired is also a good candidate. For low IBU beers, you can completely skip a separate boil hop addition, as discussed, or you can add a tiny bittering charge of hops to help break the surface tension of the beer and then add all or the majority of the IBU contribution at knockout, with the 10 to 15 percent utilization in mind.
The second factor to consider is the length of your hop stand. There are no right or wrong answers, but anywhere from 10 minutes to 90 minutes is reasonable. For most super-charged, hop-forward beers, hop stands will run 45 to 60 minutes. For a midrange hop profile, such as an American pale ale, you can usually shorten that stand to 30 minutes. If the beer is not to be hop forward, nor does it need significant IBUs from the hop stand, then a 10- to 15-minute hop stand usually will suffice.
Note: If you’re looking to turn your hop stand into more of a whirlpool along the lines of a proper brewery, you have a couple options. If your brewing system has a pump, you may opt to set up a tangential inlet for your kettle to allow the pump to perform the whirlpool for you. Keep in mind that you do not need a vigorous whirlpool—just a simple spinning of the wort. If you do not have a pump, a simple spoon or paddle will work to achieve a similar result.
Three temperature profiles that seem to be popular among homebrewers are just off boil range—190 to 212°F (88 to 100°C)—the sub-isomerization range—160 to 170°F (71 to 77°C)—and a tepid hop stand range—140 to 150°F (60 to 66°C). The 190 to 212°F (88 to 100°C) range will allow essential oils with higher flashpoints an easier time to solubulize into the wort and also will allow some alpha acid isomerization to occur with the best estimates of between 5 to 15 percent utilization. Some homebrewers will keep their kettle burner on low to keep the temperature of the wort elevated above 200°F (93°C) during their extended hop stands, which would better emulate the conditions in commercial whirlpools. A hop stand in the 160 to 170°F (71 to 77°C) range will basically shut down the alpha acid isomerization reaction, and the lower temperatures will reduce the vaporization of the essential oils. Homebrewers can use their wort chillers to bring the wort down to this range before adding the knockout hops or they can add a second dose of knockout hops. The 140 to 150°F (60 to 66°C) range will once again reduce vaporization of the low flashpoint oils, but it may take longer to get the same amount of essential oils extracted.
Dry Hop Considerations
Another factor to consider is how to handle dry hopping your hop-forward beers if you employ an extended hop stand. Rock Bottom Restaurant & Brewery performed an extensive study on hop stands and dry hopping under the guidance of the Portland, Oregon, brewmaster at the time, Van Havig, (now of Gigantic Brewing Co. in Portland). The study was published by the Master Brewers Association of the Americas Technical Quarterly and considered beers that were hopped in four different ways: short hop stand (50 minutes) and no dry hops, long hop stand (80 minutes) and no dry hops, no hop stand and just dry hops, and finally half the hops in hop stand (80 minutes) and half the hops for dry hopping. Beers produced using exclusively hop stands and the beers produced using exclusively dry hops will both result in well-developed hop characteristics, but there were some nuances.
The long hop stand developed more hop flavor and aroma than the short hop stand, indicating that essential oils were still soaking into the wort after 50 minutes. The exclusively dry-hopped beer received its best marks in the aroma department, higher than the hop stand beers, but scored lower for its hop flavor. The beers where only half of the hops were added for the hop stand and half were added for aroma ended up scoring high in both departments. Havig’s study also showed that adding 1 pound/bbl (0.45 kg/bbl) Amarillo dry hops produced the same amount of hop aroma as 1/2 pound/bbl (0.23 kg/bbl), indicating diminishing returns at higher dry hop rates.
So if you are just giving this technique a try, here is a suggestion based on the study’s findings. Take all the hops you plan to add for late addition hops and dry hops and cut them in half. Add half at knockout and the second half as a dry hop addition. Again, don’t feel the need to go overboard with these additions.
What is it about a beer like Russian River Brewing Company’s Pliny the Elder that is so striking? To anyone who has tasted or brewed a beer such as Pliny the Elder, it’s the hop oils that knock your olfactory senses sideways. Thanks in a large part to groundbreaking work by Thomas Shellhammer, Nor’Wester Endowed Professor of Fermentation Science at Oregon State University, and his former student Peter Wolfe, who now resides as brewing scientist at Anheuser-Busch InBev, our understanding of the extraction process has advanced that much more. Using some advanced dry hopping techniques, we can use this science at home to achieve hop bliss.
Dry Hop Basics
The definition of dry hopping is adding hops to your wort after the boil, after it’s been cooled—and typically when fermentation is almost finished or completely finished. This is different from other hop additions, even finish hopping or using a hopback, because the hops aren’t exposed to heat when dry hopping and therefore do not cook. Without heat, the hop alpha acids do not isomerize and hence do not add bitterness like hops added to hot wort, which contribute to bittering.
There are a few different ways to dry hop, depending on the variety and form of hops you plan to use. Selecting a hop variety for dry hopping is subjective. Some brewers prefer using aroma hops that have a low to medium alpha acid rating, such as Cascade, East Kent Golding, Saaz, Glacier, or Willamette. Other hop-happy brewers like the character of more aggressive high-alpha varieties, such as Chinook and Simcoe (for a list of hop varieties and characteristics, visit Brew Your Own). There are no hard and fast rules.
Choose a form of hops that you will feel comfortable handling for your brewing setup. Whole leaf and pellet hops are both easy to add to a carboy, and if you’re using a fermenter with a larger opening, you can put your hops in a sanitized grain bag and steep them like tea. A good rule of thumb is to use around 0.5 to 2 ounces of hops for a 5-gallon (19 L) batch, depending on the variety—though aggressive IPAs and double IPAs will often call for much more.
Once you’ve chosen your hops, you can add them to your cooled wort. Some brewers like to add the hops to the primary fermenter. If you choose to add them at this point, you need to account for some aroma loss from the release of CO2 by adding more hops than you might think you need.
Most brewers add their hops to the secondary fermenter, or at least after primary fermentation has finished, which avoids aroma loss problems. Plus, beer in the secondary has finished fermenting and has a lower pH, so there is less of a risk of contamination from anything on the hops (which is a low risk either way).
Additional details follow, but in general you’ll steep your hops for a week or two if you’re using ale temperatures and 2 to 3 weeks at lager temperatures. Keep tasting your beer throughout the process until you find the flavor you want, if you’re new to dry hopping. Then, rack your beer away from the hops or remove the hop bag and you’re ready to start bottling or kegging.
More from Big Book of Homebrewing
- Guide on Closed-System Racking Methods
- How to Clone Beer Recipes
- Advanced Dry Hopping Methods
- How to Pitch Yeast
Excerpt from Big Book of Homebrewing, by Brew Your Own, published by Voyageur Press. Copyright © 2017 by Quarto Publishing Group USA Inc. All rights reserved.