Fermentation restarted during dry hopping?

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rphtx

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I am doing a Dogfish 60 IPA clone and pitched 2 vials of White Labs WLP002. This was my first use of my spiffy new refrig with digital temp control. Primary was fermented at 70-71 deg, which was a bit low but I was worried about fermentation starting.

Anyway, fermented for 2 weeks in the primary and hit pretty near the FG. I secondaried to do the dry hopping. I dry hopped with pellets and half of them sank and half stayed on the top for several days and it took my clear ale and made it really cloudy. After a week of cloudy dry hopping with little clearing, I decided to drop the temp to about 67-68 thinking it might help clear it up a bit.

I checked the next day and my airlock was bubbling and I swear that another small amount of krausen has formed. Is this possible that fermentation never really completed and dropping the temp a bit would have restarted fermentation? I know most will say just let it go and see what happens, but has anyone experienced something like this?
 

smizak

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What's happening is the CO2 is coming out of solution because of the added nucleation sites provided by the hop pellets. No re-fermentation. It's the same as adding Mentos to Diet Coke.
 
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rphtx

rphtx

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Wouldn't that happen sooner than later...why would I start to see this 8 days into dry hopping? This is a continuous steady bubbling that has occurred over the past few days.

So, do I wait until the stuff clears back up or stops bubbling?
 

ZenBrewer

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smizak, normally, I would totally agree with your response of nucleation as a culprit. However, there are a few things off on this.


  • The time spent in the secondary prior to the apparent "fermentation" was on the order of a few days, not seconds/minutes as you would normally see with a solid added to a gaseous liquid knocking the gas out of solution.
  • The second oddity was the fact that the OP experienced the release of gas after dropping the temperature. A liquid is able to to contain a larger volume of dissolved gas at lower temperatures.

So, that being said, I believe it is possible that fermentation had not finished and that the transfer from the primary to the secondary could have swirled up enough of the highly flocculate WLP002 as well as (potentially) exposing enough O2 to the brew to restart the aerobic process of yeast reproduction. This may be the cloudiness you are seeing as well. The small drop in temperature probably didn't do anything.

I wouldn't suppose you took any gravity readings??

-ZB
 

mithion

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This has happened to me with the WLP002 strain as well. I don't know exactly what causes fermentation to spontaneously restart especially after lowering the temperature. The only explanation I can think of is that dry hopping caused the release of dissolved CO2 which subsequently kicked up some yeast from the bottom. And because your beer was mostly finished fermenting combined with lower yeast population in secondary, maybe it just took several days for the yeast to get active enough again for visible signs of fermentation.

You might wonder if it took so long for fermentation to restart again, why didn't the yeast just flock out again. Well I think highly hopped beers like IPAs affect the cellular membrane of yeast and possibly affects the flocculation characteristics which could explain why the yeast stayed suspended long enough to become active. This is all speculation and I hope somebody more knowledgeable may correct me if I'm wrong.

Personally speaking, I'm very interested in the flavor characteristics of WLP002, but it has given me so much grief that I've given up on using it myself.
 
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rphtx

rphtx

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Zen..nope haven't took and gravities since the day I secondaried. I don't like cracking the top for any reason, but it was close to the intended final gravity. The comments from you and mith seem to confirm that fermentation restarted. I thought infection at first, but the top layer looks like a good healthy krausen. It is no wear near as violent or active as it was in the primary, but the temp drop probably did it.

So, now I will need to wait again for it to finish and clear a bit...what effect will having hops in there 2-3 weeks instead of the originally intended 7 days lol? Is it bad leaving them in so long? I haven' messed with dry hopping and am not sure if the hops get leached of flavor at some point and then become insoluble junk or if keeping it going causes any negative effects..

Thanks for the responses...this was my first go with WLP002 as well and I had heard some of the 'grief' associated with it. I like a challenge though.
 

BklynCyclone

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I've experienced the OP's situation many times. Every time I dry hop my fermentation ratchets back up again. This last time I had my beer in the primary for 2 weeks and in the secondary for another week after that before I dry hopped it. Now it's bubbling away again with no signs of slowing 5 days into the dry hop... Temps are at 66 and have been consistent throughout the fermentation, so I'm not sure what this phenomena is... I would imagine that the CO2 coming out of the solution would end in a day or so, and I'm pretty sure this thing is going to go for 2 more weeks... (as has been my experience in previous batches). Any ideas?
 

as1084

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Hey. This just happened to me Saturday night with a belgian IPA. I was only a couple points off from my FG in primary for 2 weeks, so I racked into secondary on top of 2 oz of hop pellets. I woke up the next morning only to see krausen forming again and my beer really cloudy. I am not interested in why this happened cause from what I have read, nobody is really sure. What I want to know is since my beer restarted fermentation, is it going to affect the aroma I would be getting from dry hopping? Should I dry hop in a hop bag in the keg just to make sure I get the aroma from dry hopping? Or will my beer get the aroma despite fermentation restarting in secondary? Thanks!
 

BklynCyclone

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What I want to know is since my beer restarted fermentation, is it going to affect the aroma I would be getting from dry hopping? Should I dry hop in a hop bag in the keg just to make sure I get the aroma from dry hopping? Or will my beer get the aroma despite fermentation restarting in secondary? Thanks!
So far I can't complain. The Black IPA I made is still going somehow. I have to check but I'm pretty sure it's been in the secondary for 3-4weeks (hops have been in 2-3 weeks) now. The same thing happened last time and it turned out fine with good citrusy and piney notes from the cascade hops.

Funny thing is that my wheat beer is ready for the keg now and I brewed that a week after the Black IPA... I'll post an update once it stops bubbling...
 

beerhappy

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Well it's officially been 10 days since I've dry hopped my English IPA and I'm still seeing some turbulent activity. Wort is still cloudy and small chunks of yeast are moving up down. The beer has been in the fermentor at total of 18 days now so I think I'm gonna bottle regardless. I wanted to bottle quickly to preserve the freshness of the dry hop as much as possible. But this phenomena is causing delays and I'm worried this will adversely affect the final product. I guess we'll see afterwards.
 

TTB-J

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Well it's officially been 10 days since I've dry hopped my English IPA and I'm still seeing some turbulent activity. Wort is still cloudy and small chunks of yeast are moving up down. The beer has been in the fermentor at total of 18 days now so I think I'm gonna bottle regardless. I wanted to bottle quickly to preserve the freshness of the dry hop as much as possible. But this phenomena is causing delays and I'm worried this will adversely affect the final product. I guess we'll see afterwards.
I would just go get another ounce of hops, wait for fermentation to actually finish this time and then nail that bad-boy with another shot of dry-hoppy-goodness. The beer will taste better if you let it ferment out in bulk, so why not go for the gold? 18 days in the fermenter is not that long. I left my last pale ale in the carboy for a month.
 

bzwyatt

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Necropost I know, and if there are other threads more relevant please link. I looked through a couple but I'm sure there are a lot more.

I brewed Northern Brewer's Mongoose EIPA 3 weeks ago, with S-04. Primary for two weeks at 66-68, transferred to secondary with 2 oz EKG a week ago. Still moving around and bubbling a bit. I guess I'll wait another week but this is new for me. Is S-04 known for restarting fermentation?
 

snagy2

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Super late to the thread but I found some great info out from Vinne C at Russian River (via the session) Hops have natural sugars and a refermentation does occur when added after primary has completed. They joked on the show that a mini diacetyl rest was even relevant when dry hopping.
 

Miraculix

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Just read an article that actually said that dry hop has diastetic enzymes on the surface that can convert longer sugars to shorter ones.... From 1890. So it looks like dry hoping can actually produce more fermentable sugar and therefore yesterday fermentation when introduced.

Doesn't look like they have sugar on their own though.
 
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Dcpcooks

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If you moved the beer and dry hopped it you created nucleation points and your seeing co2 come out of suspension. Co2 can come out of suspension when you add hops, see a fluctuation in temps, transfer beer or barometric pressure changes. It is not necessarily an indication of fermentation. It really shouldn’t be used as a gauge of fermentation with the exception of zero bubbles in the first 72 hours. ( the last sentence still doesn’t mean a ton as you could just have a bad seal on a fermentor. )

Take a gravity sample, check it again in a few day and if it’s stable your done. If not repeat until it is.

Still moving is a sign you still have active fermentation but that could also happen after a transfer.

Cheers
 

FunkedOut

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Latest BeerSmith podcast has John Palmer as a guest.
He says that dry hops add something (enzymes?) that yeast can metabolize.
 

Brewfreedom

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Seeing this today with M44 west coast yeast on what looked like a stuck fermentation though it might just be coincidence because I added a fresh yeast starter earlier in the week. Refused to budge from 1.024 for 5 days. Added some hops yesterday and Im suddenly seeing gravity dropping again.
 
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