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Bittering Hops in 15 Minutes

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Each of the parts in this series will stand alone, but you might be interested in reading the kickoff article: 4 Tips for Making Great Beer in 15 Minutes.

One of the most wonderful things about brewing is that every step can be accomplished by a multitude of methods. The advantages of a particular method may make one preferred over others by some brewers, but this doesn't necessarily make one method universally better than the others. These 15 minute brew articles are a summary of what works for me with a focus on some techniques that you may not have heard of. My goal is that every brewer will find some useful information in these articles and, for those interested, the procedure will be laid out start to finish.
The most common method for adding hop bitterness to beer by far is the traditional ventilated wort boil, and for good reason: The wort needs to be boiled for sterilization purposes making it a convenient time to also add bittering hops. However, if the wort does not need to be boiled, as is the case for brewing with dry extracts, other options may be better suited for adding bitterness.
Hop tea can be a convenient method for adding bitterness to beer. Because a smaller volume of water is required, it takes less time get to, and return from boil. Because there is no sugar or extract in solution there is a lower chance of a boil over. And if it does happen, you aren't going to be scrubbing a sticky mess off of your stove. Hop tea can be made ahead of time for multiple batches, and it's easy to make. Hops can be boiled in water on the stove, in the microwave, or in a hot pot. Other common methods are using a percolator, or using a French Press. My book Brewing Engineering has some more details on hop tea. One of the more obscure methods is the one I will focus on in this article: the use of a pressure cooker. The same bittering levels of a traditional 60 minute boil can be achieved with a pressure cooker in 10.

Bittering six times faster may sound like a farce, but I assure you, there is no deception here, only a carefully engineered solution. Replacing your boil kettle with a pressure cooker uses the same amount of hops with the same alpha-acids to achieve the same bitterness levels. The big difference is time. Including the time for heating and cooling, a 60 minute boil may take 2 hours to complete, while a 10 minute boil in a pressure cooker can take less than 15 minutes.

For a given set of conditions, alpha-acids in hops are isomerized at a constant rate and can be described as a first order kinematic reaction. The rate at which this occurs is expressed as conversion per time and is known as the rate constant. Jaskula [1] demonstrated that the rate constant exhibits Arrhenius behavior in that the rate is a function of temperature and activation energy. Malowiki [2] demonstrated this behavior over a temperature range of 195F to 265F (90C to 130C).
Isomerization of alpha-acids in hops can therefore be expressed as a function of not only time, but temperature as well.

The equation, table, and chart summarize the relationship between temperature and conversion rate. The conversion rate is the percentage of available alpha-acids that are isomerized per minute.

The high temperature of the pressure cooker presents a new challenge that doesn't exist with the traditional boil. Along with increasing the rate of isomerization at high temperatures, the rate of degradation also increases. Using the characterization that Malowiki[2] identified, the peak in utilization can be identified for the pressure cooker and traditional boil. Using a traditional boil the maximum utilization occurs around 150 minutes. In a pressure cooker the elevated temperature causes peak utilization to occur six times faster at only 25 minutes. The hop tea will actually become less bitter if cooked for more than 25 minutes in a pressure cooker.

Dissolved alpha-acids vs pH - Spetsig[5]
When using any form of a partial boil to add hop bitterness, alpha-acid solubility must be considered. Although the same amount of isomerization occurs in a partial boil, only small amount is actually dissolved. You may have heard that 100 IBUs is the maximum achievable bitterness in beer. This likely stems from the solubility of alpha-acid, which is 90 parts per million at 5.2 pH and 20 degrees Celsius. (1 IBU is equal to 1ppm of isomerized alpha-acids[3]) In practice, the solubility will be higher at this phase in the brewing process. Spetsig[5] Characterized alpha-acid solubility and noted that solubility increases with pH. At a pH of 7 (that of neutral water), the solubility is 3000 times higher than at a pH of 5.2. This works to our advantage because the pH will typically be higher when boiling without extract. During a traditional boil, wort acts as a buffer, reducing the pH. When only boiling the hops, there is very little to buffer the solution, and alpha-acids are very weak. The result is that the pH is much closer to 7. When 1oz of 6%AA hops are dissolved in 1 cup of distilled water the pH measures about 6.5. At this pH level, the solubility is 1000ppm (or 1000 IBUs).
Using the 15 minute brew method only a small amount of water (typically 20% of the total) is boiled to speed the brewing processes. If a saturated 100 IBU solution is simply diluted five to one, the maximum resulting bitterness is a disappointing 20 IBUs. To solve this problem, we can borrow a technique from all-grain brewing: laughtering. After the hops are boiled, the vessel can be topped off with water before pouring through a strainer into the fermenter. The additional water can then be poured through the hops in the strainer. This is effectively a fly-sparge. Because the total volume of water that came into contact with the hops is the full volume of the beer the bitterness level will be the same as if a full volume boil was conducted.

For most pressure cookers, at 15 lbs of pressure, the time is simply the bittering hop boil time divided by 6. To use the table above, multiply the bittering IBU target of your beer by the volume. Find the closest value in each column on the table. To the left is the alpha-acid content, and above is the weight of hops required.
Using the pressure cooker to replace my boil kettle has worked for me, and I hope it works for you.
[1] Jaskula, B. J., A Kinetic Study on the Isomerization of Hop Alpha-Acids. 2008.
[2] Malowicki, M. G., Hop Bitter Acid Isomerization and Degradation Kinetics in a Model Wort-Boiling System. 2005.
[3] http://en.wikipedia.org/wiki/Beer_me...ent#Bitterness
[4] http://en.wikipedia.org/wiki/Isohumulone
[5] Spetsif, L. O., Electrolytic Constants and Solubilities of Humolinic Acid, Humulone, and Lupulone, Ata Chem. Scand. 9:1421-1424, 1955


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Steven Deeds is "The Woodland Brewer". For more from this Brewer/Author visit him at his site, woodlandbrew.com, or find his book "Brewing Engineering" on Amazon.
From Steven, and everyone at HomeBrewTalk we want to wish you a Happy New Year!

 
Interesting idea, I think I may give this a go for a low alcohol/session IPA... mash high and for half an hour, aggressively boil for half an hour- during this time use some of the wort to pressure cook for fifteen minutes to get the IBUs. Aggressively whirlpool and dry hop and we're in business.
Good article! Given me a few ideas to play with.
 
Thank you for this series. I am teaching brewing in my microbiology lab course (we do 6 single hops per lab section with an APA recipe. Anything I can do to shorten the process is great. Wondering if I can use our autoclave (basically a computer controlled big pressure cooker) to make hop teas for all the single hops (thinking of clean flasks with cotton stoppers)? seems like it should.
Roy Ventullo
 
Thanks,
I'm glad you found this article interesting, or ay least entertaining.
On a procedural note, to minimize the chance of a boil over, I used only water and hops, the volume was near the minimum for my pressure cooker, and I used a drop of Fermcap.
 
Good question about DMS. I plan to address that in more detail later, but in a nutshell if you are using extract it has already been boiled just like you would when brewing all grain.
 
@judanero Don't put anything "foamy" in a pressure cooker/canner. Using wort and hops is a recipe for an explosion.
The vent on these things is small. If you get something foaming up and clogging that vent, and bad things will happen.
Water and hops only!
 
I'm dumb--can you give us an example of how you'd use the chart (https://cdn.homebrewtalk.com/images/1/9/3/7/2/3/hbt-steve-7-1523-full.jpg) to say, get 40 IBUs into a 6 gallon batch?
 
It's probably not you, the chart isn't as easy to follow as I would have liked, and it looks like there was an error in my equation. The chart is updated now. (Thanks Austin!)

For your example of adding 40 IBUs to a 6 gallon batch:
40IBU's * 6 gallons = 240 IBU gallons.
On Pressure cooker side, using the 0.5 oz column, the nearest number is 234. Reading to the left you'll see this corresponds to 13%AA. This means you could use 1/2oz of a 13%AA hop and boiled it in the pressure cooker for 10 minutes to achieve 40 IBUs in 6 gallons.
Under the 1oz column the nearest number is 252. Reading to the left you'll see this corresponds to 7%AA. This means you could use 1oz of 7%AA hops boiled in the pressure cooker for 10 minutes to achieve 40 IBUs in 6 gallons.
Utilization in the pressure cooker can be calculated as a function of time (in minutes) using the equation:
U = exp(-0.013t)-exp(-0.086t)
This works out to between 4 and 6 times faster than a traditional boil depending on boil time. So you can use your favorite brewing calculator and divide the time by 5 for use in the pressure cooker.
 
This is fantastic information, and from where I sit, could be used for different goals. While I enjoy the process of brewing AG, and would likely not use this to add bitterness on brew day, I would love to, on bottling day, taste and make adjustments if needed to add bitterness to the bottling bucket!
I'd love to see more info on using hop teas to take the place of dry hopping in the keg for those of us who prefer not to keg, but appreciate that dry hop character!
 
another great article. have you had any issues with tannins extraction? with a relatively low gravity and high temps wouldn't that extract a lot of tannins from the hops?
 
Good question about tannins. You are right that the high pH from a low gravity in combination with the high temperature would typically cause tannin extraction. I haven't noticed any flavor impact. It may be because the mass of the hops is so much smaller than the mass of grain that it is not a problem when making hop tea but is a problem when sparging grain.
 
I'm curious about the "quality" of the Hops bitterness and flavor.
It would be interesting to have some BJCP judges compare beers using this method and the traditional method.
This has an additional advantage -
Just as you can make wort using no chill and pitch the next day, you could make a few batches of "hop tea concentrate" at one time. So when you want to brew you boil your extract, and pour in a container of the "hop tea concentrate" you made the prior month.
 
Another option might be to use hop extract in the pressure cooker. With extract you don't have the solubility problem because the resin is already completely extracted. Taking it a step further, you could use extract in a mason jar and "pressure can" the hop extract to make a sterile, hop tea that can be added post boil to the fermenter, with this method you could stop your boil as soon as the break forms.
 
Using the pressure cooker method for bittering hops on a 5 gallon all grain batch, would you still bring the wort to a boil for 15-20 minutes? Assuming you want to add flavoring hops at 20 or 15 mins remaining... and then the aroma hops at 5 mins remaining.. Or is this method most practical for beers that only need bittering hops?
 
Thanks for this info Woodland. I just put it to use to "fix" an experimental batch that was lacking enough bittering. Upon tasting the beer after dosing with pressure cooked "hop tea", I would say that the bitterness level went up about as expected based on your chart of hop alpha/amount/IBU contribution. I look forward to the next article. Cheers!
 
Correct, from my reading of this whether you're doing AG or extract, you can bring your wort to the boil for 15-30 minutes and use this time to do your flavour/aroma additions.
This means boil time for your wort is now 15 minutes minimum.
I personally only do 5 minute flavour/aroma additions and the traditional 60 minute addition. Next on the list is a pressure cooker for sure.
 
What do you mean? Put jars of hops and water into a pot of water and boil the water to boil the water in the jars? Lid on or off? Or do mean the method you would use to pressure seal a glass jar with hops and water?
Having pressure sealed jars of bittering hop additions is adventurous and intriguing.
 
Just to clarify, the fly-sparging process for this is simply: take pressure cooker apart, pour contents into your fermentation vessel through a strainer, pour fresh water through the strainer to get the last bits of bittering?
So one could assume if you were applying this to AG, you could pour your wort into the fermentation vessel through the strainer to get the last of it's efficiency? I'd happily give up a couple minor fractions of SG points for this method even if it meant I needed to strain fresh water through and not my finished wort to get the best of the tea.
This means I could reduce my boil to flavour/aroma additions only (15 minute boil min/max)
 
I have two questions:
1. are these US gallons or imperial gallons? Or put it another way, how many litres in your gallons?
2. any problem with using an aluminium pressure cooker?
 
How much water should be put in the pressure cooker? Suppose I determine that I will need 1 ounce of pellet hops to achieve my required IBUs, then I would put the 1 ounce of hops directly in the pressure cooker with how much water? Thanks and regards - great article!
 
I want to try raw ale using this bittering method. One thing that's puzzling me is your later paragraph about dilution of IBUs. Is it not the case that I can just dump the whole hop tea in my wort?
 
Hello, using the chart at the bottom of the article, how much water is needed to get the appropriate amount of ibus listed? Thanks,
Aaron
 
Great post! I want to try this. You haven't been specific about how much water is needed per gram hops to get max utilization. 1oz per cup or 20% of traditional volume (assuming 5+ gallon boil). More importantly, what is a good way of dehydrating the extracts. evaporate away the water and get a very condensed hop extract that can be added to beer at anytime during the whole process. the volatile oils might get blown off too, but the bitterness should remain, right? thanks.
 
I thought about pressure cooking hops several days ago eating supper and looking over at our Instant Pot pressure cooker, that I have used for roasts, chicken, BBQ Spare Ribs, etc and thought to myself.... Maybe I can just pressure cook some wort and hops and reduce the overall boil time. I did it on the 28th, Dec. 2017, and talked about it on a forum. It was very successful !! Then, on the forum replies I was given a link to this article. Same idea, but obviously I did not come up with it, but in a sense, I did come up since I never knew about this article. Great minds think alike!! I do love the charts and graphs. However I took 3 cups of my fresh made wort and got it to boil in the SS kettle of the Instant Pot, and when it was at boiling temp, put the SS kettle in the Instant Pot, along with the required amount of hops I was using for the 60 minute boil (used hop strainer bag) and started the process for 15 min. At the end I merely drained the bag, slight squeeze, and added the whole to the now boiling main kettle and boiled for another 15 minutes, with the last 5 adding the final "aroma" hops of Hallertau to the kettle. Tasted the cooled wort before pitching yeast (Munich Dunkel) and it had a nice bittering profile that will do well with the EtOH and carbonation.
 
I'd like to use a variation of this method to bitter raw batches - where wort is sparged directly into the fermentor - but I'm uncertain about the IBU calculations for the tea and volume. According to online IBU calculators, the single ounce of 14.2% alpha hop pellets I boiled for 60 minutes in 26 oz of pH 7.2 water resulted in a 1931 IBU tea. I'm not sure I trust that number even though the calculators did account for the 1.0 original gravity and tiny boil volume. Even if I assume that number is valid, how do I calculate the volume of tea to add to a 5 gallon batch to hit a target IBU of 25? Is it as simple as Target IBU / Tea IBU * Tea Volume (25/1931*26 = 0.3366 oz of tea to add), or is there more to it?
I'm curious to see if hop tea/extract additions require additional aging time to "meld" the flavors.
 
Very interesting & introduces some science to the hopping process.
I did become a bit glassy eyed trying to absorb all the issues.
Frankly I think you have tried to cover too much & introduced inevitable confusion.
For my part, I need simple straightforward instructions on what to do & exactly how to do it.
These days almost everyone owns a pressure cooker, now we boil (xxxx litres) water (open top), add hops (quantity now uncertain) & pressure boil (lid on) for 15 mins (or 20 min??). Remove hop bag & add hop/water mix to fermenter.
Now what to do with the hop bag contents?
Hope you see my point; maybe several sets of recommendations to suit different brewing processes?
Thanks for your effort in presenting.
 
Great idea to use a pressure cooker. Have you tried freezing the hop tea for later use?
What do you say to people who insist on boiling bittering hops in wort not water?
PS got any top tips on how to get 23 litres bottled in 15 mins too?
 
I tried this for my latest batch of IPA, targeting 60 IBU. Using the numbers from the plots I did 12 minutes in the Instant Pot (12 psi) with 1 pint of water, which should be about 244F and a utilization rate of 5.3% per minute. My calculation actually came to 14 minutes, but I figured it's ramping up past boiling for a couple minutes. My initial tastes indicate that it was not entirely successful. Not that I know exactly what 60 IBU tastes like, but it could be more bitter. I think my issue is solubility - next time I will try two pints of water and a tsp of baking soda to make sure the instant pot doesn't become saturated.
 
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