Flavor and aroma loss - I can not figure out why this keeps happening!

[mac_1103]

It's been shown that purging an empty keg with fermentation gas is essentially 100% effective. So if you purge a starsan-filled keg instead then any oxygen that was dissolved in the starsan will also get removed unless you disconnect the keg as soon as the liquid has been pushed out.

 

[OzzyPeeps]

Interesting ... I suppose the o2 reaches equilibrium with all the co2 above it and sublimes

 

[mac_1103]

I would expect the oxygen in the starsan to come out of solution as the partial pressure of oxygen in the headspace drops. So like I said, if you watch the starsan get pushed out and disconnect the keg as soon as it starts pushing gas instead of liquid, then I think there will still be some amount of oxygen in the keg. But if you leave the keg hooked up until fermentation is complete that oxygen gets progressively diluted with fermentation gas until it's essentially gone. I think it may actually be more effective to purge an empty keg with the fermentation gas going in through the liquid post and dip tube, but I'm not the expert on this. @doug293cz is.

 

[doug293cz]

I would expect the oxygen in the starsan to come out of solution as the partial pressure of oxygen in the headspace drops. So like I said, if you watch the starsan get pushed out and disconnect the keg as soon as it starts pushing gas instead of liquid, then I think there will still be some amount of oxygen in the keg. But if you leave the keg hooked up until fermentation is complete that oxygen gets progressively diluted with fermentation gas until it's essentially gone. I think it may actually be more effective to purge an empty keg with the fermentation gas going in through the liquid post and dip tube, but I'm not the expert on this. @doug293cz is.

Pretty good reply. Starting with an empty keg and letting the purge go the entire length of the fermentation, you end up with less than 5 ppb (yes parts per Billion) O2 in the purged keg. Starting with a liquid filled keg would end up slightly lower, but you wouldn't be able to measure the difference.

Brew on

 

[BongoYodeler]

When I'm fermenting oxygen sensitive beers I purge the receiving keg with fermentation through the liquid post and dip tube. But even before brew day, starting with a cleaned and starsan sanitized keg, I hit the keg with a single shot of 30-35 psi CO2 from the tank. I pull the prv to evacuate, thinking I'm still left with at least some CO2 that wouldn't normally be in there, hopefully giving me a little better starting point when I hook it up to capture CO2 once fermentation kicks in. Good idea or waste of time and CO2?

 

[day_trippr]

Regardless, it can't hurt, but still I would vote "waste of time and CO2" - but only because I don't do that, and still have kegs of neipas - perhaps the most O2 sensitive style ever - that are still tasty after 6 months...

Cheers!

 

[OzzyPeeps]

The benefit I see with using liquid in the idea I posted above (attempting to dry hop in a purged keg) is that it would take significantly less time vs just with ferm gas.

The way I see it, the longer hops are sitting there with gas blowing through them the more aroma you are losing.

There's a reason they are vacuum packed in mylar under nitrogen immediately after harvest/processing.

My understanding was that ferm gas from an entire fermentation was 100% effective for a purge ... but that's at least 7 days of blowing gas ... so for the specific application above that I want to try partial liquid would be better.

Also the perfectionist in me is looking at efficiency:

A s I understand it a fermentation produces roughly 40x the volume of the fermentor in CO2.

So with a liquid purge 1 fermentation could theoretically purge AND sanitize 40 kegs

So that's 80 birds with one stone by my math ...

You gotta sanitize anyway, nice to get it out the way

 

[OzzyPeeps]

When I'm fermenting oxygen sensitive beers I purge the receiving keg with fermentation through the liquid post and dip tube. But even before brew day, starting with a cleaned and starsan sanitized keg, I hit the keg with a single shot of 30-35 psi CO2 from the tank. I pull the prv to evacuate, thinking I'm still left with at least some CO2 that wouldn't normally be in there, hopefully giving me a little better starting point when I hook it up to capture CO2 once fermentation kicks in. Good idea or waste of time and CO2?

I'm no expert but I think the accepted wisdom is a full fermentation purge is 100% effective and even food grade tank CO2 has a bit of O2 in it so could be counter productive ... but how the hell you could know for sure I have no idea

 

[OzzyPeeps]

Not to derail the thread too much ... but for those who purge with fermgas using basic buckets or carboys as opposed to fancy pressure fermenters, does anyone use an airtight blow off jar as a sort of quarantine area as insurance against over active fermentations?

I know from a brulosophy article you can purge a keg with a basic bitch bucket or carboy ... but I use a lot of omegas lutra kveik at highish temps and she gets pukey so I don't need that in a keg I'm trying to purge but I'm unsure how to design a blow off jar I know will be airtight

 

[mac_1103]

The benefit I see with using liquid in the idea I posted above (attempting to dry hop in a purged keg) is that it would take significantly less time vs just with ferm gas.

And the benefit of taking the extra time is that you remove more oxygen. You're not going to dry hop until fermentation is done or nearly done anyway, so I don't see much of an efficiency gain. I can't really comment on whether gas moving through the keg harms the hops, but I suppose someone could set up a direct comparison.

for those who purge with fermgas using basic buckets or carboys as opposed to fancy pressure fermenters, does anyone use an airtight blow off jar as a sort of quarantine area as insurance against over active fermentations?

Yes. Krausen catcher. You can buy an overpriced one or DIY it.

 

[hottpeper13]

Ozzy google "thumper for distilling.

 

[Bassman2003]

The dry hopping question is a good one. If you put the hops in the serving keg and kept them suspended until transfer, unless you purged it beforehand, the start of fermentation would have oxygen in the keg. It would take some time to fill with CO2 and remove the oxygen. So in theory, the hops would be in an oxygen environment for some amount of time.

If you are only going to fill the keg up 80% and push out with CO2, then it seems to me you are only lessening the problem (which is not bad). But, it seems like a PITA if you filling and emptying while trying to keep the hops dry... You might be better off daisy chaining two kegs together in the previous brew/fermentation and then starting with one for the next hoppy beer. That way it is purged and dry when you quickly open it and put your magnet bag in before the current fermentation purge begins.

My goal with all of this stuff is to eliminate the use of tank gas outside of serving.

 

[doug293cz]

A s I understand it a fermentation produces roughly 40x the volume of the fermentor in CO2.

So with a liquid purge 1 fermentation could theoretically purge AND sanitize 40 kegs

So that's 80 birds with one stone by my math ...

Why would you need way more purged empty kegs than you have beer to fill them?

Brew on

 

[BongoYodeler]

Not to derail the thread too much ... but for those who purge with fermgas using basic buckets or carboys as opposed to fancy pressure fermenters, does anyone use an airtight blow off jar as a sort of quarantine area as insurance against over active fermentations?

I know from a brulosophy article you can purge a keg with a basic ***** bucket or carboy ... but I use a lot of omegas lutra kveik at highish temps and she gets pukey so I don't need that in a keg I'm trying to purge but I'm unsure how to design a blow off jar I know will be airtight

I bought one of these and a mason jar with starsan to put between my fermenter and keg.

 

[OzzyPeeps]

The dry hopping question is a good one. If you put the hops in the serving keg and kept them suspended until transfer, unless you purged it beforehand, the start of fermentation would have oxygen in the keg. It would take some time to fill with CO2 and remove the oxygen. So in theory, the hops would be in an oxygen environment for some amount of time.

If you are only going to fill the keg up 80% and push out with CO2, then it seems to me you are only lessening the problem (which is not bad). But, it seems like a PITA if you filling and emptying while trying to keep the hops dry... You might be better off daisy chaining two kegs together in the previous brew/fermentation and then starting with one for the next hoppy beer. That way it is purged and dry when you quickly open it and put your magnet bag in before the current fermentation purge begins.

My goal with all of this stuff is to eliminate the use of tank gas outside of serving.

Totally

The idea is to purge minimum headspace of approx 1 quart to hold the charge IMMEDIATELY.

I read a very convincing argument with a lot of math that said 16x would get rid of it all but whatever, do 30x in less than 60 sec.

Now we have hops which are as fresh as they possibly can be (they are still frozen so zero terpenes have boiled off hopefully) inside a keg with as close to zero oxygen as possible (the sanitizer has been doses with SMB)

Ready to rack onto as soon as it's purged...

Thats where the speed of purging liquid vs a purge gas purge comes in, theoretically ...

The thread is about retaining elusive aroma. Stands to reason that the less time the terpenoids in the hops are boiling off into the gas the more aroma is retained for the beer

How much of a difference that makes in practice comes down to a lot of variables like hop strain, and individual sensitivity of the brewer, but the science behind terpenes boiling points is pretty well established.

When you open a bag of hops, if you can smell them those terps are gone by definition

only thing that could be optimised more would be to speed up the purge with bottle gas but then the trade off is with the unknowable ppms of o2 in your bottle gas ... which gets me thinking...

What is the wisdom on when to hook up the co2 from the FV so there is defi zero o2 left in the headspace? High krausen?

Can someone explain how to multiquote on here I can't figure it out cheers

 

[mac_1103]

Can someone explain how to multiquote on here I can't figure it out cheers

Just select the things you want to quote one at a time and click on "+Quote" in the drop down for each one. Then when you click on "Insert quotes" you will see a list of the quotes you selected. When you click "Quote messages..." at the bottom of that list they'll be inserted in the order shown.

 

[mac_1103]

When you open a bag of hops, if you can smell them those terps are gone by definition

So IOW, minimizing loss of hop aroma and minimizing oxygen exposure are competing goals and unless you've got something fancier than a keg and a mesh bag you're going to have to trade some of one for some of the other. ISTM that minimizing oxygen is more important by far and you should just use more hops to compensate for the inevitable loss of some terpenoids. But I guess that can get pricey so YMMV.

 

[Bassman2003]

If you are just purging the keg and not protecting anything, one can hook it up from the start because it will all blow through in the end. If you are protecting hops, then you could be strategic and hook it up later in to the fermentation.

Another approach some do is to have two kegs attached to the FV. After some time through the fermentation, open the 2nd keg and throw your hops in. This creates and mildly purged environment to start and continues to purge going forward. When it is time to transfer, run the beer in to the keg that has the hops. Let sit for your dry hopping period, then run that beer out in to the other totally purged keg. This gives you a serving keg without any hops and also minimizes the hop contact time with beer and O2. If the hop keg was not totally purged, it would only have contact for x amount of days before the beer is moved on to a totally purged keg. Not too difficult and sort of makes the best out of the situation.

 

[BongoYodeler]

How about something like this and this?

 

[mac_1103]

How about something like this and this?

Yeah, I'd say that qualifies as something fancier.

 

[AmarikinBrew]

@MaltAndMayhem

Do you add wheat flour in mash/boil to ensure haze?

You did not cover your boil.

Do you add Campden to remove chloramines? how much? [boiling removes only chlorine]
Do you add whirflock/isinglass/Irish moss/supermoss and how much?
Yeast nutrient? -how much?

All these things can remain after the boil, and can not only affect yeast performance, but also hop oil/aroma retention. Especially if too much of one thing or a combination thereof.

If your keg has a very slow leak may affect aroma too.

 

[day_trippr]

Do you add wheat flour in mash/boil to ensure haze?

Hopefully, no.
File under "Don't Do That", it's completely unnecessary to "fake a hazy" by using flour...

Cheers!

 

[mac_1103]

I guess stranger things have happened, but why would the OP complain about haze if he had added something to create haze?

 

[day_trippr]

I dunno..."Failure To Haze?"

 

[mac_1103]

Actually, I think I got two threads mixed up.

 

[doug293cz]

Actually, I think I got two threads mixed up.

It happens.

Brew on