Best practice for purging headspace during/after dry hop

[mac_1103]

I have been told privately that the residual O2 after a fermentation gas purge has been measured using adequately sensitive analytical equipment ($$$$$), and that the results are even better than the model predicts. This is not unexpected, as the model makes worst case assumptions. I trust the individual that provided this information to me, but it is hidden behind a paywall, and I am not allowed to link to it here.

I assume this was for the single five gallon keg scenario?

 

[doug293cz]

I assume this was for the single five gallon keg scenario?

That's my understanding, since the experiment was to confirm the model.

Brew on

 

[mac_1103]

That's my understanding, since the experiment was to confirm the model.

Without giving too much away, can you tell us if the data might support updating the model?

 

[doug293cz]

Without giving too much away, can you tell us if the data might support updating the model?

I don't think there is sufficient information to update the model. To improve the model, it would have to be changed to a dynamic, rather than static, model. This would require detailed knowledge of CO2 flow rates vs. time during the fermentation, and also the detailed geometry of all the vessels and tubing involved. Way too much trouble for the benefit that would be gained.

Brew on

 

[DuncB]

I believe @sibelman has tested this out:


Brew on

I think the transfer of beer / wort into purged fermenter is the method used at Sapwood cellars as well, mentioned in a podcast by Scott or Mike, can't remember which one.

 

[CyberFox]

@doug293cz I just thought of something that you could probably help me with. I implemented the continuous purge with CO2 and purging after sealing. My beer was by far the best I've ever made and I can tell that I'm really on the right track with my process. We'll see how long it takes to oxidize, but I'm planning on purging even more next time to be safe, so it's all good.

Here's the thing...I am planning to make a pumpkin beer at some point and I was going to add spices like I would a dry hop (dry spice if you will). I think it would be a serious problem trying to add spices while doing a continuous purge (spices in your face anyone? ). I was thinking of omitting the continuous purge while adding the spices, then sealing it up and purging with 16 rounds of 30 psi to get 0 ppm of oxygen. As a reminder, I am using a 6 gallon keg as a fermenter and my batches are 5.25-5.5 gallons (headspace would be 0.5-0.75 gallons). What is your opinion on this technique and do you think it would be a good technique for all beer styles?

 

[day_trippr]

Roughly what volume of spices is involved? I have been injecting "stuff" through the keg gas port using a big syringe and a bare gas QD, dissolved in a little water if necessary...

Cheers!

 

[sibelman]

Another approach to avoiding avoiding dust: stir the spices into a bit of vodka or Everclear, then pour that in.

Too, while dry hopped beers are very oxygen-sensitive, your pumpkin beer may better survive a bit of oxygen. Could be a RDWHAHB situation.

 

[doug293cz]

@doug293cz I just thought of something that you could probably help me with. I implemented the continuous purge with CO2 and purging after sealing. My beer was by far the best I've ever made and I can tell that I'm really on the right track with my process. We'll see how long it takes to oxidize, but I'm planning on purging even more next time to be safe, so it's all good.

Here's the thing...I am planning to make a pumpkin beer at some point and I was going to add spices like I would a dry hop (dry spice if you will). I think it would be a serious problem trying to add spices while doing a continuous purge (spices in your face anyone? ). I was thinking of omitting the continuous purge while adding the spices, then sealing it up and purging with 16 rounds of 30 psi to get 0 ppm of oxygen. As a reminder, I am using a 6 gallon keg as a fermenter and my batches are 5.25-5.5 gallons (headspace would be 0.5-0.75 gallons). What is your opinion on this technique and do you think it would be a good technique for all beer styles?

Purging with multiple cycles is a good method to get the O2 out of the headspace after opening for dry hopping or similar.

Brew on

 

[CyberFox]

Roughly what volume of spices is involved? I have been injecting "stuff" through the keg gas port using a big syringe and a bare gas QD, dissolved in a little water if necessary...

Cheers!

That's a good technique. I'm planning on at least a tablespoon of spice. I'd also like to dry hop my IPAs with ground up hops (you know what I'm talking about ), so I won't be able to continuously purge while adding those either.

Another approach to avoiding avoiding dust: stir the spices into a bit of vodka or Everclear, then pour that in.

Too, while dry hopped beers are very oxygen-sensitive, your pumpkin beer may better survive a bit of oxygen. Could be a RDWHAHB situation.

I did think of a tincture, but I also wanted the ability to add powdered ingredients, so I was looking for a different overall solution. It also crossed my mind that non-IPAs could likely survive some oxygen, but I want my beer as high quality as possible and I'm willing to use some extra CO2 to get it.

Purging with multiple cycles is a good method to get the O2 out of the headspace after opening for dry hopping or similar.

Brew on

Well, if it works, it works. This might be too nitpicky, but do you think that the 10 or so seconds of contact with oxygen would negatively affect the beer even if I purge the hell out of it after sealing?


Thanks guys!

 

[sibelman]

10 or so seconds of contact with oxygen would negatively affect the beer even if I purge

Many have reported good results from this method. I applaud your commitment to optimizing quality.

 

[doug293cz]

That's a good technique. I'm planning on at least a tablespoon of spice. I'd also like to dry hop my IPAs with ground up hops (you know what I'm talking about ), so I won't be able to continuously purge while adding those either.


I did think of a tincture, but I also wanted the ability to add powdered ingredients, so I was looking for a different overall solution. It also crossed my mind that non-IPAs could likely survive some oxygen, but I want my beer as high quality as possible and I'm willing to use some extra CO2 to get it.


Well, if it works, it works. This might be too nitpicky, but do you think that the 10 or so seconds of contact with oxygen would negatively affect the beer even if I purge the hell out of it after sealing?


Thanks guys!

It takes time for beer to absorb a significant amount of O2 from the headspace, so the shorter the exposure the better. You want to get the purges done as fast as you can, consistent with getting a complete pressurize and vent with each cycle. If you can't drop from a purged chamber, your proposed method is the second best option.

Brew on

 

[CyberFox]

It takes time for beer to absorb a significant amount of O2 from the headspace, so the shorter the exposure the better. You want to get the purges done as fast as you can, consistent with getting a complete pressurize and vent with each cycle. If you can't drop from a purged chamber, your proposed method is the second best option.

Brew on

Sounds good to me. Thanks!

 

[RyPA]

Well, if it works, it works. This might be too nitpicky, but do you think that the 10 or so seconds of contact with oxygen would negatively affect the beer even if I purge the hell out of it after sealing?

I don't think so, my beers always stay un-oxidized for their lifetime (1-1.5 months) in the keg, and these are primarily NEIPA's which are prone to oxidation.

I purge probably way more than needed, but I'd rather do more than not enough. And once I pop the lid off of the keg, I have the CO2 flowing, so I like to think that CO2 is flowing out of the keg, reducing how much O2 can sneak in. Then once the keg is sealed again, I do at least 10 purges, some of which I allow the keg to pressurize before pulling the PRV, and some I just leave the PRV open to allow outward flow of CO2, and whatever O2 is in there.

Try and see what happens, and once you figure out what works, rinse and repeat.

 

[DuncB]

One foodsafe magnet in bag with spices. One magnet outside to hold it. Come the time slide spices into beer. Closed system.

 

[skratch]

Sorry to resurrect a somewhat old (but not yet ancient) thread. Regarding using fermentation CO2 to purge a dry hopper, should we not be concerned about the hops sitting in a relatively high O2 partial pressure environment until it's scrubbed? Do hops degrade less in the presence of O2 when they are physically dry? If not, then I don't see any benefit to leaving the hops sitting in a dry hopper slowly getting scrubbed vs dry hopping without a hopper before fermentation is done (same benefit of yeast scrubbing O2). I would hate to spend $200+ on putting together a dry hopper and then fail to leverage any real benefit from it.

The best option would of course be a series of true pump/purge cycles, but a vacuum pump is not a standard brewhouse item. A one-time investment to set up a nitrogen purge capability (N2 is much cheaper than CO2) would be another option. But I haven't done any legwork on costing this out and finding the break-even point.

 

[mac_1103]

Regarding using fermentation CO2 to purge a dry hopper, should we not be concerned about the hops sitting in a relatively high O2 partial pressure environment until it's scrubbed? Do hops degrade less in the presence of O2 when they are physically dry?

See posts 9, 18, 26. At least one member here says he gets excellent results, and I don't think he worries about keeping the hops dry. Also see #35 - a commercial brewery may also be using this approach. I don't dry hop very often, but I'll be using this method the next time I do.

 

[redrocker652002]

Can't really answer that question without knowing what equipment is available.

What I plan to try, for my next big dry hop load, is to place the hops in a sanitized keg, purge the keg with fermentation CO2, and then closed transfer the beer to the keg with the dry hops. Can decant to another purged keg if limiting hop contact time is desired.

Another method is to drop the dry hops in from a purged chamber, but that requires special equipment.

Brew on

I was thinking of trying this as well. If it is under pressure then I don't have to be quite as concerned about temp either, right?