Accidently bulk aging under vacuum ... problem ?

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Jim Welch

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Feb 25, 2019
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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?

It has little and probably nothing to do with the gas. Technically it is called the coefficient of expansion in physics , not "thermal contraction", although that is an apt description. Practically everything expands when it heats up and contracts when cools down. Everything does this whether it be solid, liquid, or gas. Additionally very few things have the exact same coefficient of expansion.

So I'm saying what happened here is the wine and carboy were at "55-ish" first and then in the barn dropped to "50-ish", as stated in the OP.
The glass carboy and the wine would both fractionally contract. However these compounds (i.e. glass and wine) individual coefficient of expansion are NOT equal so the wine contracted MORE than the glass and since the carboy is very well sealed this increased the vacuum. Glass has a coefficient of expansion at least an order of magnitude less than water and alcohol.

Curiously, there are some things that start to contract when cooled then at some temperature gradient begin expanding. Like plain old water, which contracts until about 40 degrees Fahrenheit then starts to expand as it cools further.
We all know the destructive capability of freezing water say in pipes or an engine block. IIRC from my education this strange behavior is due to the polar molecular structure of water, at least that was the theory then and I'm not sure if this has been eclipsed with further research.

Hope this helps you understand better what I claim.


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Sep 19, 2013
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near Milwaukee
I believe that the effect that you cite is a couple of orders of magnitude too small to explain his observation.

The OP said that the vessel held 12 gallons of wine (46 liters), and let's assume that the vessel does not change in volume at all. The volume coeffiecient of water (close enough to wine for our purposes) is 0.21E-3 per degree C (that is, 0.00021 1/ºC). If the wine cools by 3ºC, the volume of the wine would shrink by (0.00021 1/C)*3ºC*46 liters = 0.0076 liters, or 7.6 mL. The OP said that there was about 2 gallons of headspace (7.5 liters). The contraction of the wine would lower the pressure in the headspace by 7.6 mL/7500 mL, or 0.1%.

The OP reported a decrease in pressure from 5" to 12". This is gauge pressure, so we really need to compute the pressure reduction in absolute pressure. He reports that the pressure fell to (30"-12")/(30"-5") = 0.72 of the original pressure, or that it fell by 28%. (If you prefer, you could also compute this fractional decrease as (12"-5")/(30"-5").)

So we are off by about factor of 300 to explain the observation via that mechanism.
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Nov 30, 2021
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I started reading this thread because I was curious what people's experiences were with storing/bulk aging wine under vacuum and whether there are any adverse affects by doing so. I read somewhere in a previous post on this site where someone mentioned that they believe that wine stored under vacuum negatively affects the quality/taste.

Has anyone else had this experience or feel the same way? I imagine there are two camps of people on this topic and would like to hear some real life experiences.


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Jan 29, 2014
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Food Industry - - Retired
* the cyser (apple mead) referenced in the quote below got a blue ribbon last weekend in club contest, ,,, guess I should put it in the state fair to see if that set of judges was a fluke.
* in 1980s wine corking lines the large manufacturers, those who could cost it out used vacuum corking on the finished 750ml bottles. In my industry packing sauces was done with vacuum (remember don’t eat cans/ jars where the lid bulges).
* I have had a WMT discussion about “structure” loss from applying vacuum to wine. The trait which is lost under vacuum is something that is poorly defined, as in I wouldn’t be able to take samples to work and produce a structure specification with a viscometer or by running dry solids.
* The “lost” trait in the vacuum threads you read may actually be something else. I have seen several papers about carbonated wines which basically say naturally produced manans & dextran in traditional Champaign are good at creating a small/ longer lasting bubble structure, ,, than a factory wine which is carbonated with straight CO2. I don’t have access to chromatography to test for these molecules.
* there is vacuum and there is vacuum. A -5” Hg vacuum which holds 30 minutes is my definition of good enough to hold. ,, Pumps let me go to -20 or -25 inches, ,,, but why bother it doesn’t improve vacuum corking.

About a year ago we had a discussion about holding vacuum and vacuvin stoppers and check valves
so I killed a few days testing hardware. > results
View attachment 85669
* An effective vacuum set up needs to have the same seals as one would use with gas lines
* old corks get hard and are not effective at holding a vacuum
* a carboy with wine in it will release CO2 and not hold a vacuum as long as a dry system
(working definition of a good enough degassed wine was the carboy can hold a five inch Hg vacuum for 30 minutes)
* The rate of change decreases as the pressure differential decreases, There was still a slight difference on gage at thirteen months with the empty flask
* A new vacuvin check valve is effective at holding vacuum
* A new plastic check valve is effective at holding vacuum (polysulphone and nylon construction)
* To know how well a hardware setup is performing one needs to have a vacuum gage
see photo setup 1 & photo setup 2 in original thread
someone mentioned that they believe that wine stored under vacuum negatively affects the quality/taste. , , Has anyone else had this experience or feel the same way? I imagine there are two camps of people on this topic and would like to hear some real life experiences.
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