Thursday, July 25, 2013

The Benefits of a Hop Stand / Whirlpool Hopping for Hop Flavor

Whirlpool Hops


When I originally learned about the technique known as "whirlpool hopping," my first question as a homebrewer was: "Wait, how do I make an actual whirlpool?" Most commercial brewers do a literal whirlpool post-boil with a dedicated whirlpool vessel. But like many homebrewers, I use a simple copper immersion chiller, and I don't even have a ball valve installed on my kettle. No whirlpool here.

So my first tip to you, Young Whirlpool Master, is that the whirlpool hop technique is probably best referred to by the homebrew-friendly term "hop stand." Stirring gently helps — you can use either a mash paddle, sanitized spoon, or your pump — but the focus of the technique is not the physical action of whirlin' so much as the timing. A whirlpool hop / hop stand addition is done post-boil, giving the hops contact time with the wort at hot-but-not-boiling temperatures, which allows a depth of essential oils (and therefore flavor/aroma) to be extracted.

What do you do? Turn that flame off, toss your hops into the wort, and let them sit for 30-60 minutes. Once the wort reaches about 160-180 F, turn on your chiller and continue as normal. That's it! Pretty simple. But why bother to take this extra step, you may ask? And doesn't it open up a brewer to all sorts of problems?

Conventional wisdom has it that you should try to chill your wort as quickly as possible after the boil to reduce the risk of infection, hot side aeration, chill haze, or DMS. Doesn't a 30 to 60 minute hop stand defeat the whole point of having an immersion chiller or a plate chiller? And more so, isn't it a waste of hops, adding them after the boiling temperatures that ensure isomerization? Why not just dry hop some more?

Bless you for asking such astute questions. 

Risk of infection doesn't really set in until around 170 F, maybe lower, so spending a few more minutes at those temps isn't going to do much harm. Hot side aeration, in my opinion, requires some serious effort, and is rare to the point of being almost a myth. Even with a gentle stirring of the wort to keep hops in suspension, there's no real aeration happening during a hop stand; at least no more than during a normal chill. (A few minutes later, when the wort is cooler, you'll be aerating the heck out of it anyway). Sure, haze is a very real concern with hoppy beers, but one that's not likely to emerge only from the fact that you did a hop stand. All those hop particles floating around from the crazy amount of hops you likely tossed in are much more inclined to form a haze than the meezly 30 minutes you took to let them soak in. Finally, what about DMS? Well, I have yet to experience DMS just from a lag in cooling my wort. I can't recall reading any account from any other homebrewer who has, either. If you're using pilsner malt or are for some reason extra worried about DMS, arrange to boil for an extra 30 minutes first.

Now, on to the good stuff: you should do a hop stand because it captures flavor and aroma that will be driven off by the boil. Any boil. Previously, most people realized that the later in the boil you added hops, the more flavor they would contribute versus bitterness. A 5 minute addition provides more hop flavor than a 15 minute addition, while a 30 minute addition really only contributes bitterness, just not as much as a 60 minute addition. A hop stand merely extends this strategy, since hot wort still allows for the flavor-providing essential oils in hops to be extracted. Even boiling for five minutes will drive off some of that character — but seeping in hot wort won't. Or at least, not as much. Each oil volatilizes at a different temperature, listed below:

Myrcene – 333 F* (167 C)
Humulene – 210 F (99 C)
Caryophellene – 262 F (129 C)
Farnesene – 203-257 F (95-125 C)

*There seems to be some debate / confusion about the volatilization temp of myrcene. Myrcene will volatilize even at room temperature, but higher temperatures happen to speed up the process. Check out this HomeBrewTalk thread for more discussion.

Additionally, there may be some benefit to doing a hop stand at different ranges of temperatures, or adding one dose of hops immediately post-boil and a second dose of hops once the wort has cooled some. Commercial breweries that focus their hop additions entirely on the whirlpool are reporting a surprising amount of bitterness extracted, as alpha acids continue to isomerize until the temperature falls to the range of about 175 °F. This does pose some issues for the consistency of your recipes, if you really care about nailing a certain IBU number (personally, I kind of don't, as I feel IBUS are largely meaningless). A BYO Magazine article suggests calculating a 10% alpha acid utilization rate. Personally, I add my whirlpool hop addition to Beer Smith as a 10 minute addition, and figure that's close enough. I'm only shooting for a ballpark IBU figure, and I will adjust the recipe to taste for the next time. 

Of course, this is assuming you're adding the whirlpool addition right after flameout, when the wort is still hot enough to isomerize the alpha acids. Generally, this is what I have done: switch off my burner, dump in the hops, put the lid on, and hop stand for about 30 minutes, stirring every now and then. When the 30 minute hop stand is over, the wort has usually cooled down to around 180 F. I then turn on the water flow and let my chiller cool the wort to pitching temp.

However, if you don't want to get any bitterness from the whirlpool addition, there is an adaptation to the method that will accommodate this, seeing as you probably won't get any more alpha acid isomerization once the temp drops below 175 F. One method is to turn on your chiller for a few minutes until the temp hits the 170 - 180 F range. The lower temperature will, in theory, reduce the vaporization of essential oils. Of course, going further down, past the 160 F range, even further reduces your chances of driving off low flashpoint oils, but I'm not sure this is really necessary, personally.

Of course, there is also the option for a split addition approach, which I believe is what I will be doing for my hoppiest beers in the future. Add some of the hops immediately after flameout, let stand for 20-30 minutes (or until the temperature has dropped to ~180ish F), then add the rest of the hops, and let stand another 20 / 30 minutes. Then cool down to pitching temps. In this way, you should cover the best of both worlds.

The temp and timing is up to you, and there seem to be a number of methods that would bring good results. You're going to have to adjust for your brewing system, which is likely different from my brewing system, and almost certainly different from a commercial brewing system. You're also going to have to adjust for the recipe you're brewing, and your tastes. 

I was skeptical when I first read of this technique, assuming it was one of those "Well, if you've got enough hops that you want to cram them in at every possible moment..." indulgences (I'm looking at you, mash hopping). However, the more hoppy beers I brew, the fewer hops I've been adding to the boil. For hop-forward styles, I find myself adding hops at First Wort, just a bit at 60 minutes, and flameout + hop stand. If your goal is to extract as much flavor and aroma as possible, is there really a benefit to grabbing those few IBUs achieved with a 15 or 10 minute boil addition? You could get the same from a minuscule bump in your 60 minute or FWH addition. What I really want out of my hops is flavor — the bitterness part, that's easy. Whatever brings me closest to that unadulterated hop flavor, that's what I'll be doing.



30 comments:

  1. There's definitely a lot of old school myth perpetuated about how fast you must cool your beer. Almost all commercial brewery systems do some sort of whirlpool (maybe not the very small systems) as a matter of necessity, which adds time to how long the wort is hot. For particularly large breweries, there's just no way to cool that much wort that quickly. If all those concerns were legitimate then it would be impossible to brew a light lager on an industrial scale. We know that is not the case.

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    1. Yep, exactly! I think we're seeing a shift in people thinking "Well, commercial brewers have no choice in this due to to scale," to now realizing, "But actually, there's an unexpected benefit to having to do that."

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  2. Nice write-up.

    I agree, hop-standing really adds a lot of hop character. I recently brewed a hoppy wheat (Modern Times Fortunate Islands clone), that involved hop extract at 60 minutes for bitterness, then a total of 4 oz Citra and 2 oz Amarillo at flameout. The original recipe made use of a Hop Rocket, March pump, etc... so I compromised by adding half the hops at flameout for a 10-minute hop stand, then I turned on my chiller and added the other half.

    The recipe also has a huge dry hop, but when I took a gravity reading before adding any, I couldn't believe the aroma on this beer already.

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    1. Yeah, to be honest, I wonder if a thorough hop stand might actually be more effective than a hop rocket on a homebrew scale. The hop stand should allow for more contact time with the hops, and other than filtering, I'm not sure what the advantage of the rocket might be. More enclosed? I would love to see a side-by-side comparison.

      This write up was actually inspired by a hoppy wheat beer I'm doing, though I wanted to do another Belma focused beer, mixed with Amarillo and fermented with Conan. I started to turn this into a recipe / hop stand explanation post and decided it was enough info to just stand on its own.

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  3. Great post. this one technique totally changed my brewing approach and style.I too, find myself adding less and less boil hops and more hopstand hops. now that I,ve started doing this, I can't go back, hoppy beers aren't the same without it. couple of thoughts: This works as well for session strength beers as it does for big IPAs. Make sure you calculate for some extra absorption from evaporation during the hopstand as well as absorption from the hops you throw in. this technique works awesome on all-Brett IPAs as well.

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  4. I agree the post flame, pre-chill, additions add a lot of great things to the beer. I hadn't thought about the different temperatures after flame out though! At NHC I listened to Stan Hieronymous' talk on hops and there is sooooo much left to learn about how and when adding hops affects the wort, and then after fermentation, the beer. I am thinking about just doing firt-wort and flame out additions to my next batch. Then I will split it and drop hop half, leave half as-is and see what happens!

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    1. It's amazing that we've been loving hoppy beers for a couple decades now, and are still totally overhauling our techniques every now and then. There is always more to learn. Keeps it fun.

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  5. I just did a hop stand for the first time. Cooled wort to 165 degrees with immersion chiller, turned off chiller and added 5 oz. of hops. Let sit for 30 min. with lid on the kettle and would give a gentle stir about every 5 min. After 30 min. I turned on the chiller and cooled to pitching temp. This was all in addition to a 60 and 10 min hop addition during the boil. There was no perceived change in bitterness but the flavor was significantly ramped up with an awesome complexity that I had not achieved in my IPAs previously. Hop stands will be the norm form now on.

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  6. Once again a timely and informative article Derek! I commented over on your "Culturing Conan" article and now have brewed a clone Heady Topper recipe (BYO's - I know, I know). It included a whirlpool/hopstand, which I enjoyed doing. From the sound of it I did it how you described your process...at flameout. Let sit for 45 min., (dropped to 175) then chilled/strained/pitched. I agree that its amazing that we're still discovering and refining brewing techniques after all these years.

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  7. Very good text. I have read on BYO (April 2013 Hop Stand text) that the 140 to 150 °F is the only range that really will not vaporizate the essential oils, or at least preserve the most of it.

    Is there a real risk of infection below that temperature? I keep hearing people talk about not going below 170F but... the Citra I got here in Brazil were very expensive, I cant afford to just vaporize the damn precious oils!

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  8. Actually, the risk of infection does not set in until one gets below 140F.

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    1. This is very wrong. Generally 170 is safe, no lower.

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    2. I've done whirlpool/hopstands many times at 150F range with no infection or issues. So your not right either.

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    3. Agreed...I do a lot of my hopstands at 140 with no issues.

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    4. There's too much worrying about infection and hop stands. I no chill when I do hop stands because I want the most aroma/flavor extraction possible. I just use painters tape around the lid of the pot sealed down well. This is airtight enough. As long as no air is getting in after you start your hop stand, you aren't introducing new microbes. (the steam in the kettle or chill cube will kill any non-spore things)

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    5. Going up, 140F is when Pasteurization of liquids begins... meaning the killing off of all microbial organisms. I do this with my cider and it stops fermentations cold 'cause it kills everything. Holding any liquid at 140 for an hour or so will almost sterilize it. So I have a very hard time believing that a 140-150F stand *increases* the likelihood of infection, when it's precisely the temperature range we shoot for when we're trying to *kill* microbes.

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    6. Alex, by "I no chill when I do hop stands..." do you mean that you let the wort cool naturally down to pitching temp? If so, do you have a way to strain off the hops before the temp gets down there, or do they stay in contact with the wort the entire time?

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    7. It depends where you are on this blue planet. In England open fermenters can work well. In Australia apparently there are too many airborn nasties. So safer at lower temps in England.

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  9. This is extremely helpful info!! Very good work. Everything is very interesting to learn and easy to understood. Thank you for giving information.
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  10. Being new to brewing I find this info so valuable, and will be modifying my system to whirlpool as soon as the parts arrive to start this hopstand technique on batch #5. I am searching for the best iipa I have ever had, and I feel pretty fortunate to have found what I was missing with the flavor component, there is no doubt this is it. No more cooling as fast as possible, never again, steeping for flavor and bitters, dry hopping for fragerance. Thank you all!

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  13. Question, if this practice of hoping can give bitterness and also enhance flavors, then is there a point to boil the wort for 1 hr? or to put it different by using this hop addition technique is it possible to lower the wort boiling time?. Great article btw!!!

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