Accidently bulk aging under vacuum ... problem ?

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chonn

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I have 12 gallons of wine in a 14 gallon stainless fermenter - just did the third racking.

So that's a lot of headspace ...

I very, very liberally poured in A TON of co2 - like it was pouring out the bunghole like a witches cauldron then I quick slid on a bung with a valve and then pulled something like 5" hg vacuum.

Why did I do this ?

I think there is still a bit of fizz/co2 in my wine and since I can't possibly get a totally perfect 100% headspace displacement of ambient air with my co2, why not suck some of the headspace back out and let it fill with the last bits of co2 from the wine ... not only do I get the last bit of co2 out of solution BUT I also improve my oxygen situation (if only slightly).

BUT WHAT actually happened is that I pulled 5" hg vacuum, then came back later that day to find it at roughly 10" vacuum and now it's at something like 12 ...

Here is what I think:

- High flow co2 straight from the bottle must be "hot" and when you fill up a space with it and walk away, it must "cool" and reduce in volume.

- My wine was probably 55-ish degrees when I did this and temps dropped a bit in the barn and it is something like 50-ish degrees now.

So ... I think it's just a volume/temp/contraction issue and my 5" vacuum just turned itself into a 12" vacuum.

Do I care ?

Can I just leave it here for another two months with a vacuum that fluctuates on temperature and when the wine temp rises enough I will probably bubble out the last bit of co2 and re-fill that space and ... ?

Comments appreciated ... thank you.
 
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Just to follow up ... I am thinking this through and I see my question is incomplete ...

Instead of asking "what does a 12" hg vacuum mean for bulk ageing" what I should be asking is "what does a 12" hg vacuum @ 50F mean for bulk ageing".

Since the vacuum/pressure is useless by itself - we need the temp as well.

I cannot find a converter that tells me what a vacuum @ one temp will convert to if we raise the temp ... but I suspect at 60F my vacuum is quite a bit less than the 12" I have grown into as of this afternoon ...
 
Welcome to WMT.

Can you confirm whether you are referring to "gauge" vacuum or "absolute." That is, before you start sucking with the vacuum pump, does your gauge read 0", or does it read 30"?

The relationship between pressure and temperature is simple: P = const * T. However, you need to use absolute temperature (i.e., room temperature is ~300K or ~540 Rankine, if you want to use non-metric units). Also, you would need to use absolute pressures, where no air at all is 0, and atmospheric pressure is 760 Torr (or 30" if you want to use non-metric units).
 
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Can you confirm whether you are referring to "gauge" vacuum or "absolute." That is, before you start sucking with the vacuum pump, does your gauge read 0", or does it read 30"?

I am using the gauge that is on the little hand pump (brake bleed pump).

So when I first attach it, it is at zero and then I pumped it down to -5" and then a little later I came back to find it at -12".

Am I right that freshly poured co2 from a bottle must be "hot" and it must shrink a fair amount as it cools - which would explain my mystery vacuum increase ?
 
No, I don't think that can explain it.

First of all, the percentage change in pressure is way too large. Assume for a moment that your explanation is correct: the CO2 comes out hot, and that eventually it cools down to ~300K. To match your observations, the CO2 would have to have come out of the bottle at about (30"-5")/(30"-12")*300k=416K, which is the same as 143ºC or 290ºF. Obviously that is too hot.
Second, in actual fact, gases cool upon expansion. Therefore, the CO2 will be cooler than room temperature as it expands out of your bottle, not hotter. (This is due to the relation PV=const*T, which I alluded to above, but now accounting for a change in Volume.)

I am at a loss to explain your observation. So much so that (and I mean no offense here), I question the observation. When I have used a brake bleeder on anything (brakes, wine, etc.), the pressure always tends back towards zero relatively quickly. Is it possible that when you were pumping, the needle got sort of stuck at 5", and then got unstuck when you weren't watching?
 
I am at a loss to explain your observation. So much so that (and I mean no offense here), I question the observation. When I have used a brake bleeder on anything (brakes, wine, etc.), the pressure always tends back towards zero relatively quickly. Is it possible that when you were pumping, the needle got sort of stuck at 5", and then got unstuck when you weren't watching?

Thanks for your comments - appreciated.

What I did was pump with the brake bleed pump to 5" vacuum, then I crimped the hose between the pump and the tank since I don't want to bump the pump and bleed it accidently.

So the tank is totally crimped closed. Hand pump stays at around 5". Then I UNCRIMP the hose a few hours later and the pump jumps down to 12" vacuum.

OH ...

... am I somehow confusing the reading by going from a tiny little volume (pump + 6" of 1/4" hose) to a big vacuum (the headspace of the tank) and if there is a small divergence between those two vacuums it somehow makes the pump gauge double itself ... or something ?

If that is what is happening, how can I get a true reading without losing the existing vacuum in the tank ?
 
what you are seeing is similar to ”brick” pack coffee at Aldi or rice from Tilda.
product is filled into the package > CO2 is added > package sealed > CO2 dissolves into the product. ,,, This is a good way to preserve product that may oxidize!
turned itself into a 12" vacuum.. . . . Do I care ? . . . Comments appreciated ...
When a vacuum is pulled on a 10,000 gallon tank it can collapse. You are dealing with a smaller vessel so you have survived.
At a year aging I routinely will use vacuum instead of air lock on carboys to manage head space. The technique works.

Welcome to WMT
 
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This is cool to read. Thanks for posting.

And welcome to WMT!
 
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what you are seeing is similar to ”brick” pack coffee at Aldi or rice from Tilda.
product is filled into the package > CO2 is added > package sealed > CO2 dissolves into the product. ,,, This is a good way to preserve product that may oxidize!

I considered that scenario, but I did not take it too seriously because of this in the OP:

I think there is still a bit of fizz/co2 in my wine

... but maybe you are correct.
 
At a year aging I routinely will use vacuum instead of air lock on carboys to manage head space. The technique works.

Thank you very much. I wonder, how much of a vacuum do you pull and how much do you see it fluctuate ?
 
I considered that scenario, but I did not take it too seriously because of this in the OP:
... but maybe you are correct.
if I am tasked to make a carbonated beverage for Brazil the CO2 dissolves onto the lab bench beverage matrix, , , , and he was adding CO2 for an inert gas. ,,, anyway CO2 flushing is a neat fairly easy in the packaging line way to make rigid rectangular bricks of vacuum packed food materials.
 
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How do you age under vacuum?

I don't really want to but ...

IF you have co2 still dissolved in your wine (wine is fizzy) and IF you have a fixed size container and don't have 500 extra gallons of wine to fill up the headspace with (ie., small home producer) THEN ...

... you use a pump to pull a little vacuum which causes the extra co2 to boil out.

BUT IF, LIKE ME, you pull a little vacuum one last time and there is no co2 left to boil out, you're stuck at a vacuum and you don't want to "fix" it because that's another round of oxygen exposure and my 14 gallon tank filled with 12 gallons of wine is an ENORMOUS head-space.

So ... then you go on a forum and ask if letting the thrice-racked wine age for a month or two under a 12" hg @ 50F vacuum is OK ...

... and it sounds like it is OK, especially since 12" hg @ 50F is probably ... a very small vacuum at 70F, right ?
 
My look at it is that CO2 is useful, it helps protect the wine. As a result I avoid degassing till I want to bottle. How much? The 12 volt pump I use will pull 21 or 22 inches Hg. This is “used“ to fill the head space with an enriched CO2 atmosphere which a check valve can hold in place. If I am aiming for a high percentage CO2 I may “flush” the atmosphere out two or three times, waiting for the pressure to equalize.
A working definition for a fully degassed is that the carboy can hold a five inch Hg vacuum for thirty minutes. In my experience to get this takes time as half a day, and it isn’t really worth while to let the pump spin, it takes time or mechanical mixing for speed. The carboy will lose vacuum/ equalize with a CO2 headspace with time. This isn’t a constant ie the time becomes longer as the percentage gas is reduced. ,,, it doesn’t really fluctuate, it reaches equilibrium at which time the gage remains stable.
B62A445C-5611-4F09-A09B-B5E9435B39C6.jpeg
I wonder, how much of a vacuum do you pull and how much do you see it fluctuate ?
1) some parts of age in red wines are related to micro oxidation, at this point I haven’t figured out why I want to copy what happens in a HDPE vinegar jug or wood barrel. 2) The age process which decreases fruity aromatics will happen with time, removing oxygen/ evaporating CO2 will delay loss of aromatics, ,, I haven’t figured out why I want a less fruity tasting wine. 3) part of aging is tannins complexing into larger size molecules, what I have read suggests tannins will create complexes without oxygen.
How do you age under vacuum?
 
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... and it sounds like it is OK, especially since 12" hg @ 50F is probably ... a very small vacuum at 70F, right ?

The difference between 50F and 70F is minuscule, as far as vacuum is concerned. 50F = 510 Rankine. 79F = 530 Rankine. The ratio is 0.96. A change from 50F to 70F would increase the pressure by 4% (although the temperature change would not, by itself, change the number of molecules).
 
My look at it is that CO2 is useful, it helps protect the wine. As a result I avoid degassing till I want to bottle.

See, that's exactly what I thought.

I liked the co2 dissolved in the wine and thought it was protecting it from oxygen, etc.

But then I read (reddit ?) that dissolved co2 keeps particulates or super fine debris in suspension and you can't fully clear the wine while it is still fizzy.

So that is why I decided to degas fully and then bulk age for another two months without dissolved co2 ... but I sure felt a lot safer with the fizzy wine ...

I also read somewhere else that dissolved co2 doesn't necessarily prevent oxidation. I asked if the presence of dissolved co2 "proved" that I had not oxidized yet and they said "not necessarily".

Comments ?
 
dissolved CO2 does not prevent oxidation! The quantity of any (every) gas dissolved in a liquid is a linear function of the partial pressure (basically the percentage in the head space) of the gas times an experimentally determined constant. If we have an air lock there will be some gas transfer so a safe approximation is the ullage follows atmospheric pressure. There is roughly 20% oxygen in the atmosphere so every time the air lock is removed oxygen is added to the ullage. BUT in the early fermentation CO2 is produced and flushes that air out so a reasonable assumption is oxygen is zero percent and the CO2 is preventing oxidation. Everything changes after outgassing stops and the percent of each gas in the head space should be assumed to be at atmospheric levels. . . . . This is a long way to say the flushing action prevents oxidation. . . . . With my vacuum pump and a check valve I basically am flushing out the atmosphere and hoping that dissolved CO2 comes out and pressures decrease so there isn’t a driving force to pull atmosphere back in.

Next, the gas solubility is related to temperature. This means that on the warmest day of the year CO2 will evaporate out of the liquid. In the cold season/ winter the wine will hold more gas that wants to come out if it warms up. ,,, practically speaking all wine holds just enough CO2 for the summer temp equilibrium in your climate.

I also read somewhere else that dissolved co2 doesn't necessarily prevent oxidation. . . . Comments
 
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@chonn Depressurizing gases always get cold, air conditioners use this mechanism to cool. What you are seeing is thermal contraction due to the reduction in the wine's temperature as you suspect. At least you know the wine container is very well sealed!
As an aside, where I work there are hundreds of CO2 fire extinguishers, plant maintenance inspects them monthly and would swap the expired ones out and store them until a couple dozen were on hand then have the fire protection company come get them and renew them. I have on more than one occasion used one of these to rapidly chill warm beer by putting the beer in a paper bag and hitting it with the CO2. The very first time I did that I overdid it, froze that 6 pack solid as a rock! No beer after work that day.
 
@chonn Depressurizing gases always get cold, air conditioners use this mechanism to cool. What you are seeing is thermal contraction due to the reduction in the wine's temperature as you suspect. At least you know the wine container is very well sealed!

I am unable to follow what you are claiming. What is "thermal contraction"?

I think you are saying that his initial pump out cooled the gas left in the headspace. Fine, I won't argue against that. But then how does that factor explain the later observation that the pressure dropped even farther over time?
 

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