Shaking the Carboy Leads to Oxidation?

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Ace_Club

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Twice now I've seen Revvy reply to someone who's been shaking their carboy that that will lead to oxidized beer. While I'm not a proponent of shaking carboys, it piqued my curiosity.

Now I may be wrong here, but this is the way I think about it. The wort has been fermenting and expelling CO2, so there should be no O2 in the head space as it would have been expelled due to the pressure. So, if all you have is CO2 in the carboy, then shaking the fermenter and splashing the contents shouldn't pose a risk of oxidation at all.

Again, just curious.
 

Revvy

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You sure as hell increase the risk of it, especially if you have violated the co2 barrier in some way, like, for example opening it up to take a hydro reading, or move it or any number of things. Your Co2 cushion is only as safe as you make it. If you get o2 in there, and then shake it, you are going to shake that oxygen into the beer.
 

Revvy

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We recommend swirling the fermenters gently to re-rouse the yeast. That's NOT the same thing as shaking the heck out of it, which new brewers think they need to do.

This is the take away message, of my repeated warnings.

From How to brew.

2a. If you have a bottling bucket (see Figure 66) gently pour the priming solution into it. Using a sanitized siphon, transfer the beer into the sanitized bottling bucket. Place the outlet beneath the surface of the priming solution. Do not allow the beer to splash because you don't want to add oxygen to your beer at this point. Keep the intake end of the racking tube an inch off the bottom of the fermenter to leave the yeast and sediment behind.
From "Beer Brewing and Dissolved Oxygen" http://www.eutechinst.com/tips/do/09_DO_beer_brewing.pdf

Oxygenation: When and How Much?
Before it all begins: Pre-fermentation
Oxygen is introduced to the wort after boiling, and prior to the addition of yeast. ... the oxygenation process should take place before, not after fermentation has commenced. As fermentation progresses towards completion, oxygen uptake is reduced, and any additional oxygen injected into the wort will not be used off. Instead, it remains to react with other compounds in the beer, creating staleness and undesirable tastes.

...Oxygen control after the beer is brewed
At the end of fermentation, the beer is completely free of oxygen. At this point, the beer is highly susceptible to oxidation, which has the following effects on the end-product:
- Undesirable taste
- Cloudy/ hazy beer
- Increased beer astringency
- Darkened beer colour
There are several ways to prevent oxidation of the beer after fermentation, one of which is to blanket tanks with inert gases. Use only de-aerated water for dilutions, as well as to run through beer transfers, and keep the finished product in cool storage during the supply chain.
From BYO magazine. http://***********/stories/techniques/article/indices/7-aeration/1949-aerating-wort-techniques

Oxygen in beer is undesirable except at one point (and only one point) in the brewing process. That lone point is when the post-boil wort has been chilled down to fermentation temperature, but before the yeast has been pitched into it.
Though more recent info also adds that in high grav brews it is ok to add more O2 to the beer within the first 12 hours.

There's nothing wrong with carefully rousing the yeast, but it IS important that the brewer be careful doing it.
 
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Ace_Club

Ace_Club

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That's what I figured. Theoretically it wouldn't oxidize your beer, but in practice you never know.

Thanks!
 

Walker

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yeah, I wouldn't really worry about it. even if you disrupted the CO2 blanket and got some air in the head space of the thing prior to shaking it, air is about 78% nitrogen and 20% oxygen.
 
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Ace_Club

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Again, I don't shake my carboys, just was curious as the reasoning didn't make sense to me from a theoretical standpoint.
 

Walker

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Yeah, I don't shake them either. Not because I am worried about oxidation, but because I don't check gravity and don't worry about whether my yeast needs to be roused. :D
 

Revvy

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That's what I figured. Theoretically it wouldn't oxidize your beer, but in practice you never know.

Thanks!
If you've read much of my writings, you see I care very little about "armchair theorizing." I care about practical experiences, and preventing people from ruining their beer.

We Know oxygen and fermented beer is bad. We also know that we aren't all fermenting in airtight containers and most of the folks who think they need to shake their beer are 1)going by airlock activity and trying to make their airlock bubble, because they believe that is more important than what the beer is REALLY doing. 2) Their beer is further along the fermentation process than they know i.e. there is more than likely more fermented beer in there than unfermented beer. ANd had they taken an hydro reading they would have known this, and not felt the need to shake anyway. 3) They more than likely HAVE violated the co2 barrier in some way anyway, so it's better to assume there is 02 in the fermenter than not to. 4)Most new brewers don't understand that we're not trying to add more o2 at this time but trying to lift the yeast back into suspension. 5) Most of the brewers starting out thing MORE is better...so More yeast, more oxygen (but oddly enough rarely more time) and therefore more shaking.

So to me it's better to make sure they understand that the need to be careful.
 
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We recommend swirling the fermenters gently to re-rouse the yeast. That's NOT the same thing as shaking the heck out of it, which new brewers think they need to do.

This is the take away message, of my repeated warnings.

Though more recent info also adds that in high grav brews it is ok to add more O2 to the beer within the first 12 hours.

There's nothing wrong with carefully rousing the yeast, but it IS important that the brewer be careful doing it.
Revvy, I understand about when and when not to add oxygen and the effects it has. But if you have a sealed carboy that has been fermenting (i.e. producing CO2, then if you shake it and splash, there will be no introduction of O2 into the wort.

I agree though, it's not something you should be doing as you don't want to risk ruining a batch of beer.
 

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I think the little you get in during bottling will probably just get used up by the yeast. White claims that during a normal fermentation the yeast only need 30 minutes to scavenge all available. You are starting another smaller fermentation when you bottle condition. Just don't get 'stupid'.
 

Revvy

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Revvy, I understand about when and when not to add oxygen and the effects it has. But if you have a sealed carboy that has been fermenting (i.e. producing CO2, then if you shake it and splash, there will be no introduction of O2 into the wort.

I agree though, it's not something you should be doing as you don't want to risk ruining a batch of beer.

Well that's fine for you to believe. But I hold little faith in the integrity of a stopper or an airlock or a bucket seal.

Plus, unless I a)leave my fermenters alone undisturbed and therefore KNOW there is a nice tight cushion protecting my beers. b) Am fermenting in a corny or a conical Which are the only TRUE airtiight fermenters I can think of for homebrewers I'm not going to trust the safety in shaking a fermenter.

And also I believe more that the typical new brewer's fermenters are not going to be as safely protected as mine or yours, my experience has been that the new brewers who think they need to shake their fermenters have already violated it in some way. That I'm going to advocate them NOT shaking it.

That's the distinction I make between your theory and a typical new brewer's practice. You really can't opt for the safe theory a lot of times, where new brewers are concerned. They often have just enough understanding of what's going on to be dangerous.

Once upon a time, a couple years back when the "Olive Oil Oxygenation" discussions were flying around. Some brewer on their very first batch, and not understanding ANYTHING about the brewing process, and after reading about people using 1 drop of oil, thought "Well if 1 drop of oil works, then 1 tablespoon (or whatever the amount was) must work better." And he started an is my beer ruined thread, but didn't mention that he added the oil. And many of us spent a couple days trying to trouble shoot hos problem. FINALLY he mentioned he added the oil....

And of course the beer was ruined, and had to be dumped....And he did it with NO UNDERSTANDING about anything about the brewing process..

So yeah, I get a little concerned when certain things are tossed about causually, even like this.

Yes in a perfect world of sealed fermenters shaking SHOULD have no effect on the beer, just like in the perfect world of a sealed fermenter an airlock SHOULD bubble. But I know, most of our breweries and our fermenters and our knowledge is far from perfect...

So yes, you are right in your theory.......but I believe that where a new brewer is concerned, that where things like this are concerned it's better when giving advice to a new brewer, to err on the side of cautious behaviors.
 
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Ace_Club

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So yes, you are right in your theory.......but I believe that where a new brewer is concerned, that where things like this are concerned it's better when giving advice to a new brewer, to err on the side of cautious behaviors.
We could have ended this thread many responses ago with just this. :D
 

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Old thread i know. I was wondering the same thing as Ace and did a search. I've got a NWPA in the secondary right now with pellet dry hops and only a small amount of head space. Per the brewery's advice (where I had got the recipe) I used a starsan sanitized tube & stone connected to my co2 tank and I pumped co2 through the beer about 3 times in the last 3 days to arouse the settled hop particles. I was curious maybe slightly concerned about introducing oxygen but I really didn't see any way for oxygen to make its way into the carboy either. Turned on the co2 and had co2 coming out of the stone before it ever went into the beer and everything. I felt like i took all the right precautions we will see how it turns out :mug:

Thanks for the back and forth guys. Amazing what a search will do instead of asking a question that you know someone had to have asked at one point already.

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