Find the Oxygen Source...process help.

[okbecker]

Hello all! So several of my batches have been dinged, in competitions, lately for being Oxidized. All of these batches were of moderate gravity 1.050's and were less than 2 months old. Ingredients used were ordered from NB approx week prior to brewing ( yeast and hops were fresh). I am attempting to determine where the Oxidized flavors may be coming from in my brewing process and am looking to the masses for any experience they may have on this matter. I am aware of what causes Oxidation just trying to locate the weak link in my process. The only new addition to my process as of late is using the Better Bottles with racking adapters/spigots to ferment in...

Process:

1. Build water profile using RO water. All water and additions are added to 5 gallon keg day prior to brewing ( if chalk is used I generally bubble C02 through keg to help dissolve).

2. Water heated to desired strike temp. Water added to mash tun, grains added etc.

3. Boil, generally 60 or 90 minute. Fairly vigorous. Immersion Chill.

4. Transfer Wort to Better Bottle Carboy with Racking Adaptor and spigot. (generally carboy is not moved or touched during fermentation)

5. Fermentation complete. Use spigot with tube on better bottle to transfer wort to keg. tube reaches bottom of keg. Kegs are purged with CO2 prior to transfer and immediately after.

6. Carbonate kegs to desired volumes.

7. If bottling for comps - use a counter pressure bottle filler.

Any insight out there?

 

[bja]

I don't see anything obvious there. I also don't put much faith in competition judging.

 

[PlinyTheMiddleAged]

I'm with bja.

The only comment I would provide is to fill your keg through the beer out port. I fill my keg to the very top with sanitizer. Then I hook up CO2 and a picnic tap and empty the keg. Now I have a keg full of CO2. Disconnect the CO2 in line.

Next, I keep the keg sealed. I pull the vent so now I know the keg is at atmospheric pressure but still full of CO2. Then I transfer from the fermenter to the keg through the beer out post. You just need to pull the vent once in a while as the pressure builds in the keg and the fermenter stops draining as a result. The beer never sees air during the transfer so oxidation is minimized.

Maybe your picking up oxygen during bottling? Do you use O2 absorbing caps? Flush the bottles with CO2 prior to filling?

Good luck!

 

[wardens355]

Can you tell any flavor differences between bottles you fill and your keg pours?

 

[brick_haus]

Yea, process looks good. I agree with PTMA^^ in that it must be something during the bottling process

 

[McKnuckle]

With no empirical proof to cite, I'd bet that the culprit is your bottling process. Sounds like you're perfect up to and including the kegging part.

 

[okbecker]

Thanks for the posts thus far all. I will try to fill my kegs as Pliny has suggested, sounds like a great way to further reduce oxygen. As far as bottling goes, the bottles are purged with CO2 prior to filling with counter pressure filler and O2 caps are also used.

Good question Warden, to me the keg pours always taste better than the bottles do. Perhaps is a mouthfeel or dispensing issue as I always have better CO2 and head pouring from the keg. Then again when I drink from the keg its usually freshest, the bottles may sit for a bit or have been shipped off to comps.

Also just thinking - I have been brewing 3 gallon batches lately. After ferm I typically rack right to a 5 gallon keg - I may not be purging all of the 02 out as I have thought. May need to up the purging process at this stage and see what comes of it.

Thanks All!

 

[okbecker]

Have any of you tha bottle with a CP filler come across issues with O2 during your process ? If so, any tips or tricks would be great !?

 

[bja]

Also just thinking - I have been brewing 3 gallon batches lately. After ferm I typically rack right to a 5 gallon keg - I may not be purging all of the 02 out as I have thought. May need to up the purging process at this stage and see what comes of it.

Thanks All!

Bingo!

 

[okbecker]

One additional thought, and anyone with experience can way in, I generally leave about 1-1.5" of headspace left in bottle - even with purging perhaps this is the culprit.....

ahhhh- racking my brain now..lol...

 

[kanzimonson]

It's most likely the partially filled keg. If you're only going to partial fill, then you're going to have to do what PlinyTheMiddleAged suggest - filling entirely with Starsan and then dispensing all of it with CO2.

 

[Gavin C]

Using a 3 gallon keg might aso be of benefit.

Your process looks solid. Reducing keg headspace might be of use.

 

[carvetop]

Try the closed transfer from fermenter to keg as mentioned. Made a huge difference for me. Also, always cap on foam when bottling.

 

[kanzimonson]

And if the thought of "wasting" CO2 just to empty a keg full of Starsan bothers you, you could probably figure out some way to recapture the CO2 in another keg as the beer fills keg #1

 

[wardens355]

It's most likely the partially filled keg. If you're only going to partial fill, then you're going to have to do what PlinyTheMiddleAged suggest - filling entirely with Starsan and then dispensing all of it with CO2.

I seal the keg, then leave the relief valve open and inject CO2 through the out-post and dip tube, so the CO2 should displace most of the air from bottom to top inside the keg. I guess I don't really see the necessity in filling completely with liquid then purging it to rid most of the air in there.

If the issue is isolated to bottles, I would suggest trying to fill the bottles almost completely full by slowly pulling the bottle filler out as the bottle gets full while continuing to pour, and maybe even let a bit of foam/beer overflow and cap immediately. Two people would make this go smoother. I typically fill my bottles until there is only a couple cm of head space and cap. It's kind of a PITA because the pressure needs to be set low enough to get very minimal foaming, and it takes a while to fill the bottles.

 

[kanzimonson]

I seal the keg, then leave the relief valve open and inject CO2 through the out-post and dip tube, so the CO2 should displace most of the air from bottom to top inside the keg. I guess I don't really see the necessity in filling completely with liquid then purging it to rid most of the air in there.

Because it's not evenly displacing everything, and the gases are mixing. Why don't you try siphoning some tea or other colored liquid into the bottom of a water glass and see how evenly it stratifies as you suggest.

Now I will say that I do what you describe when I fill my kegs, but I'm usually filling them to the brim, and I'm confident that my final multi-purge of the full keg is sufficient. But if I were only partially filling it then I definitely wouldn't trust the O2 content of all that headspace.

 

[wardens355]

Because it's not evenly displacing everything, and the gases are mixing. Why don't you try siphoning some tea or other colored liquid into the bottom of a water glass and see how evenly it stratifies as you suggest.

Now I will say that I do what you describe when I fill my kegs, but I'm usually filling them to the brim, and I'm confident that my final multi-purge of the full keg is sufficient. But if I were only partially filling it then I definitely wouldn't trust the O2 content of all that headspace.

It's a bit misleading to compare it to two liquids mixing. The liquids are at the same pressure, and there is a lesser density difference: CO2 is 1.5 times as dense as air, whereas tea is probably under 1.1 times as dense as water, unless you like super sugary tea.

OK, worked through this with gage pressure in mind. Two purges empty keg @ 15 psi should give you approximately 25% air, 75% CO2, no stratification. Two purges post-fill @ 30 psi should give you approximately 2.8% air, or 0.6% oxygen (20% oxygen in air). If you purge 5 times at 30 psi, you will be 0.1% oxygen. So assuming you get absolutely no benefit through stratification, you should decrease the air by 50% each time you purge at 15 psi, 67% every time you purge at 30 psi.

Now if you have the relief valve open before you start purging, you are pushing the upper air volume out before it has a chance to vigorously mix, so I assume you have a much greater ratio of carbon dioxide to oxygen than above, and if you pressurize and let sit, maybe it gets better with any limited stratification.

I have filled a few 5-gallon kegs with 2.5 gallons of beer and haven't had issues with oxidation, but there will be some oxygen in there as seen above.

 

[wilserbrewer]

Woa, atmospheric pressure is 14.7 psi, so if you purge with co2 at 10psi gauge, or 10psi above the at
Atmosphere, the resultant mixture is ONLY around 40% CO2....been a while since the one room schoolhouse, but I think I'm close.

 

[wardens355]

Woa, atmospheric pressure is 14.7 psi, so if you purge with co2 at 10psi gauge, or 10psi above the at
Atmosphere, the resultant mixture is ONLY around 40% CO2....been a while since the one room schoolhouse, but I think I'm close.

Good catch. Will revise.

Edit: And I haven't even started drinking.

 

[okbecker]

Yep, I'm convinced the KEGS are the culprit....sometimes you need a good sounding board and audience to get to the Root Cause!...I have been filling keg with 3 gallons of brew, sealing then applying CO2 at roughly 15 psi until equalized - then hit the relief valve a few times. After reading several of your guys posts I can def see that I have just been mixing CO2 with O2 then purging off a combination of the 2 but not all of the O2. I just started brewing smaller batches this year and did not foresee this happening, never did happen with 5 gallons (makes sense though due to smaller head space). Gotta love HBT!

 

[wardens355]

Yep, I'm convinced the KEGS are the culprit....sometimes you need a good sounding board and audience to get to the Root Cause!...I have been filling keg with 3 gallons of brew, sealing then applying CO2 at roughly 15 psi until equalized - then hit the relief valve a few times. After reading several of your guys posts I can def see that I have just been mixing CO2 with O2 then purging off a combination of the 2 but not all of the O2. I just started brewing smaller batches this year and did not foresee this happening, never did happen with 5 gallons (makes sense though due to smaller head space). Gotta love HBT!

I wonder if you could somehow attach an oxygen absorber to the keg lid after you fill partially. They are pretty cheap. I have a ton of them for tossing in grain buckets and hop bags.

 

[okbecker]

Interesting...I have not seen or used these before. Guess I need to do a search online and check them out. Thanks!