Contamination from Dry Hops?

[Gavin C]

Do you have any proof of the highlighted portion, it goes against what I would consider to be reasonable sense. I just want to know it's not.

Edit: the pressure thing is obviously silly, but pure C02 is still heavier then normal breathing air. Every time I've racked the secondary kicks airlocks bubbles for awhile.

Rack to a secondary or add anything to a liquid with dissolved CO2 and you will cause some CO2 to come out of suspension. The result is bubbles in your airlock. All that's happened is CO2 is coming out of suspension assuming your not adding anything to create a true second fermentation.

The non-existence of a CO2 blanket or a gas blanket of any kind in the known universe is quite plain. For proof look no further than yourself. You and all mammalian air-berating life exists. If a CO2 blanket formed the lower 0.2% of our atmosphere would be CO2 and we would not be alive.

Denser gasses do not form layers in this manner.

Rack your beer to an air-filled vessel and you have beer and air above it. Purging with CO2 will of course minimize this but all gasses are constantly mixing. They simply don't behave in this manner for any sort of appreciable time-frame.

There is a good youtube video of a tin-foil boat floating on a heavy gas, something hexafluoride if memory serves. Usually it gets posted the minute anyone disputes the absence of the magical blanket.

It's quite hard to post evidence of a negative. It's simply not something that exists. Keeping a fermentor sealed with an airlock allows the headspace to be filled with CO2 as a result of fermentation. A closed system almost. The gasses are still diffusing through the bung, the starsan etc, but it's very slow.

Open the system, rack the beer and this is gone. Sure you kick some out of suspension and the bubbles will make you feel good. That's OK. The increase in partial pressures of CO2 is going to be negligible though. Hence the need for small headspace and the design of beer and wine bottles we all come to view as normal.

A secondary vessel for long-term storage is just that. A great big bottle. Fill it like you fill any beer bottle. All the way to the neck.

The kinetic theory of gasses is not new. Purging vessels with inert gasses, minimizing headspace and keeping vessels as tightly sealed as feasible are the way we brewers offset the effects.

https://en.wikipedia.org/wiki/Kinetic_theory

 

[joshesmusica]

Rack to a secondary or add anything to a liquid with dissolved CO2 and you will cause some CO2 to come out of suspension. The result is bubbles in your airlock. All that's happened is CO2 is coming out of suspension assuming your not adding anything to create a true second fermentation.



The non-existence of a CO2 blanket or a gas blanket of any kind in the known universe is quite plain. For proof look no further than yourself. You and all mammalian air-berating life exists. If a CO2 blanket formed the lower 0.2% of our atmosphere would be CO2 and we would not be alive.



Denser gasses do not form layers in this manner.



Rack your beer to an air-filled vessel and you have beer and air above it. Purging with CO2 will of course minimize this but all gasses are constantly mixing. They simply don't behave in this manner for any sort of appreciable time-frame.



There is a good youtube video of a tin-foil boat floating on a heavy gas, something hexafluoride if memory serves. Usually it gets posted the minute anyone disputes the absence of the magical blanket.



It's quite hard to post evidence of a negative. It's simply not something that exists. Keeping a fermentor sealed with an airlock allows the headspace to be filled with CO2 as a result of fermentation. A closed system almost. The gasses are still diffusing through the bung, the stars etc, but it's very slow.

Not to mention that in the closed system of the primary, the yeast will consume all of the oxygen present. According to the book about yeast by jamil and Chris white, all of the oxygen in the wort will be consumed within 30 mins of inoculation! I'm assuming any oxygen in the headspace early on is consumed just as quickly, especially with a krausen exposed to that headspace.

 

[Gavin C]

I'm assuming any oxygen in the headspace early on is consumed just as quickly, especially with a krausen exposed to that headspace.

I think it's more a case of the partial pressure of oxygen being diluted lower and lower. With CO2 production the concentration of CO2 increases and the resulting CO2 richening gas is burped out the airlock. As fermentation proceeds the partial oxygen pressure will become negligably low with the partial CO2 pressure approaching but never reaching 100%.

There very well may be oxygen absorption initially, (not a bad thing of course at that point) but I would suggest it's not the main player.

 

[unionrdr]

That's the question, then, isn't it? How much o2 is absorbed/mixed into the Co2? Then how much is " burped off" after that percentage of absorption is reached? And how long does it actually take, since, at this point, nasties can get the air/o2 they need to reproduce?

 

[Gavin C]

Almost all of the O2 in the headspace of the FV (assuming no leaks) will be eliminated. No doubt about that. The partial pressure of 02 will be close to zero without ever getting there.

O2 absorption won't occur as it can't go against the concentration gradient of dissolved O2 in the beer intentionally added by the brewer.

This is an entirely irrelevant point IMO and not an issue.

 

[SatanPrinceOfDarkness]

There's a Facebook group and website called Milk The Funk that is pretty expert at identifying things like this. To my eye, that white stuff looks a bit like a Brett pellicle I have going, except that yours is broken up by the hops. Is the white stuff a very light, almost feathery layer? Pellicles form to keep oxygen out of wort when microorganisms want it that way. Supposedly they go away on their own eventually (well after the beer has been funked of course). It's usually recommended that you wait to transfer until the pellicle goes away. Plus, if it is mold it will only become more apparent.

 

[m00ps]

Not to keep straying too far off topic but I though we were breathing like ~80% nitrogen......

 

[unionrdr]

I don't think it's irrelevant, as gases do mix to a point. Just wondered how long, etc, since some more scientific types brought it up some time ago now.

 

[ncbrewer]

Do you have any proof of the highlighted portion, it goes against what I would consider to be reasonable sense. I just want to know it's not.

Edit: the pressure thing is obviously silly, but pure C02 is still heavier then normal breathing air. Every time I've racked the secondary kicks airlocks bubbles for awhile.

This video is really interesting: [ame]https://www.youtube.com/watch?v=_oLPBnhOCjM[/ame]
It shows that the denser gas doesn't stay on the bottom.

 

[unionrdr]

So I assume I should've said diffusion? They do mix, but at different rates, depending on the gravity of the gasses. Assuming the gravities of o2 & Co2 to be similar to the first experiment, than they do mix, or diffuse into each other over several minutes time.

 

[watermelon83]

Thx ncbrewer!

 

[danbme]

So the beer is done. I am worried it might get people sick as one friend did say it gave him the ****s. I have had some but have not gotten ill. I plan on drinking more for research purposes.

Will a steri-pen kill the bad stuff and allow us to drink this beer?

 

[unionrdr]

What gave him the Hershey squirts was the live yeast in the beer. Home brew has that effect until your system gets used to it.

 

[joshesmusica]

Any unfiltered beer or bottle-refermented (conditioned) beer will have yeast still in suspension, not just home brew.

Those that aren't used to it (aka the BMC crowd) will definitely experience some of that. Though I will say, even if your system is "used" to it, drink a few in a night, and you're still likely to get a little.

 

[unionrdr]

I've found that allowing hop sacks to float, no matter how much boiling & sanitizer soakings, can get funky. When I dry hop & dry pepper my Hellfire IIPA soon, I'm going to use one of my new 2 gallon bags with a sanitized shot glass to sink it. I think keeping it away from mixed Co2/o2 in the headspace will help...