# carboy aging



## bluedart (Feb 5, 2021)

My 1 gallon of Baco Noir wine has completely cleared and now I want to bulk age in the airlocked carboy for 9 months. I have added one campden tablet and will not be racking again. Will the campden tablet continue to protect the wine for the next 9 months.


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## Scooter68 (Feb 5, 2021)

Normal process is to rack every 3 months and dose with K-Meta at that time. You are pushing you luck if you don't dose with K-Meta or at least take the time and effort to determine the SO2 level in your wine. 
Also even though your wine appears perfectly clear, you may be surprised at what precipitates out during that 3 month time.


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## bluedart (Feb 5, 2021)

So you are saying that the kmeta lasts about 3 months? But what about wine that is in a bottle for 1 or 2 years?


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## Scooter68 (Feb 5, 2021)

It can last longer but you can't be certain unless you test it. 

In a bottle the wine is considered sealed from exposure to oxygen and the SO2 stays in the bottle.


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## bluedart (Feb 5, 2021)

OK thanks


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## tradowsk (Feb 5, 2021)

When bottled, the cork allows a very, very small amount of gas exchange between inside and outside. But in a carboy with an airlock, gas can escape fairly easily out the airlock with enough pressure. Hence why you would need to dose with kmeta more frequently in bulk aging vs a bottle.

I don't think you need to rack if there's no or very little sediment. But you can top up the kmeta after 3-4 months in the carboy just to be safe.


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## bluedart (Feb 6, 2021)

OK good to know - thanks


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## MHSKIBUM (Feb 6, 2021)

Scooter68 said:


> Normal process is to rack every 3 months and dose with K-Meta at that time. You are pushing you luck if you don't dose with K-Meta or at least take the time and effort to determine the SO2 level in your wine.
> Also even though your wine appears perfectly clear, you may be surprised at what precipitates out during that 3 month time.


Why do you need K-Meta for wine racked in bulk but not when it's bottled. If the air gap is kept close to the stopper, what's the difference?


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## winemaker81 (Feb 8, 2021)

MHSKIBUM said:


> Why do you need K-Meta for wine racked in bulk but not when it's bottled. If the air gap is kept close to the stopper, what's the difference?


The short answer is that free SO2 binds with contaminants and neutralizes them. Once in the bottle nothing new can be introduced, while the carboy is not sealed in the same fashion.


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## bluedart (Feb 8, 2021)

tradowsk said:


> When bottled, the cork allows a very, very small amount of gas exchange between inside and outside. But in a carboy with an airlock, gas can escape fairly easily out the airlock with enough pressure. Hence why you would need to dose with kmeta more frequently in bulk aging vs a bottle.
> 
> I don't think you need to rack if there's no or very little sediment. But you can top up the kmeta after 3-4 months in the carboy just to be safe.


How much KMeta would you need to add per gallon?


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## MHSKIBUM (Feb 9, 2021)

If I add K-Meta to bulk aged carboy, should I put in more K-meta before bottling 4 months later?


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## Chuck E (Feb 9, 2021)

bluedart said:


> How much KMeta would you need to add per gallon?



About 1 gram per gallon is a "good rule of thumb."


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## sour_grapes (Feb 9, 2021)

MHSKIBUM said:


> If I add K-Meta to bulk aged carboy, should I put in more K-meta before bottling 4 months later?



Yes, that is the right thing to do.


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## bluedart (Feb 9, 2021)

Chuck E said:


> About 1 gram per gallon is a "good rule of thumb."


OK great thanks!


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## Raptor99 (Feb 9, 2021)

Chuck E said:


> About 1 gram per gallon is a "good rule of thumb."



According to numerous sources, 1 Campden tablet is equivalent to 0.44 g Kmeta: Campden Tablets vs. Potassium Metabisulfite question.


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## NorCal (Feb 9, 2021)

The big question is what is your pH. If your wine is 3.3 pH it requires 5X less SO2 than if it were 4.0 pH

I've never used Campden tablets, but saw this. _ Each Campden tablet equals 1/16 teaspoon of sodium metabisulfite and will impart approximately 75 parts-per-million of sulfur dioxide (SO2) to each gallon of wine._

If this is the case and your wine is in the 3.5 pH area, you are good for a while.


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## Raptor99 (Feb 9, 2021)

There is a helpful chart at the bottom of this page: https://www.accuvin.com/wp-content/uploads/2015/04/How-SO2-and-pH-are-Linked.pdf It gives the target range of free SO2 based on the pH level. Here is more technical information: http://srjcstaff.santarosa.edu/~jhenderson/SO2.pdf

At pH 3.4 you only need 32 ppm free SO2, so half a Campden tablet, or 0.22 g Kmeta per gallon would be enough. But at pH 3.8 you would need twice as much.

Here is a formula for calculating how much Kmeta powder to add: 
(ppm free SO2 needed) x (Liters of Wine)/0.57=(mg of potassium metabisulfite to add)
Source: Managing Sulfites in Wine


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## MHSKIBUM (Apr 22, 2021)

Scooter68 said:


> Normal process is to rack every 3 months and dose with K-Meta at that time. You are pushing you luck if you don't dose with K-Meta or at least take the time and effort to determine the SO2 level in your wine.
> Also even though your wine appears perfectly clear, you may be surprised at what precipitates out during that 3 month time.


Does K-Meta need to be stirred in carboy? There's so little air gap, even a thin stir rod causes carboy to overflow.


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## Rembee (Apr 22, 2021)

Rack off a gallon of the wine into a clean container. Add the amount of k meta that you need and stir. Then you can rack the gallon back into the main batch. I solve this problem by adding my potassium metabisulfite into an empty carboy before I rack the wine into it. This way the wine being racked stirs it up as it swirls in.


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## winemaker81 (Apr 22, 2021)

There is a product that acts like Alka-Seltzer, a SO2 tablet that fizzes and dissolves. I was going to buy some last fall, but it was out of stock. I need to see if it's available.


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## Mike Parisi (Apr 23, 2021)

MHSKIBUM said:


> Does K-Meta need to be stirred in carboy? There's so little air gap, even a thin stir rod causes carboy to overflow.



If you have a wine thief, try using that to stir. It won't displace much of the wine at all.


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## Raptor99 (Apr 23, 2021)

I wonder about this. Do you uncork your bottles every 3 months and add Kmeta? If the carboy is sealed with very little headspace, why would you need to open it and add Kmeta every 3 months? On a percentage basis, the air in a carboy is less than in a bottle of wine. If you seal it with a cork or a cap, and it doesn't leak, I don't see why you would need to open it and add Kmeta.


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## cmason1957 (Apr 23, 2021)

Raptor99 said:


> I wonder about this. Do you uncork your bottles every 3 months and add Kmeta? If the carboy is sealed with very little headspace, why would you need to open it and add Kmeta every 3 months? On a percentage basis, the air in a carboy is less than in a bottle of wine. If you seal it with a cork or a cap, and it doesn't leak, I don't see why you would need to open it and add Kmeta.



The answer to that question is in one of your assumptions, it does leak, without a doubt. The interference fit in the top of the carboy isn't that good.


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## winemaker81 (Apr 23, 2021)

@Raptor99, expanding what @cmason1957 said, the SO2 gets used up. It works by combining with contaminants, so over time the SO2 level is reduced. Given the relative leakiness of any winemaking container with respect to corks, contaminants are introduced to the wine.


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## Raptor99 (Apr 23, 2021)

@cmason1957 I understand your concern. @winemaker81 Would SO2 also get used up in bottles sealed with corks? From what I understand, wine aged in bottles with corks can breathe a little bit, which helps with aging. Wine aged in barrels also breathes. So I guess the key questions are:
* Can you seal your carboys so that they do not breathe more than an equivalent amount of wine in a bottle or a barrel?
* Is there a risk of harmful microbes getting into your carboy during bulk aging?

Several people on this forum have commented that they bulk age their wines. I would be interested to hear what they have to say about this issue.


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## winemaker81 (Apr 23, 2021)

@Raptor99, this is a complicated issue and I'm not going to tell you I'm an expert. Following is my understanding.

Wine contains contaminants from the crush, more is introduced by various actions. Light and heat affect wine. The SO2 binds chemically to contaminants and renders them harmless. ALL bulk aging containers have flaws, and racking has the potential to introduce contaminants.

Sounds absolutely horrible, right? No one is going to have wine survive the first week!  

Nope. Between the ABV, the acid, and (sometimes) the sugar, wine has a built-in preservation system. It handles all the low level threats without human intervention.

We add SO2 to provide a higher level of protection. SO2 addresses oxidation, microbial attacks, etc -- to a point. We protect our wine from the air and other sources of contamination as best we can, so the SO2 has less to do. Think of it as a multi-layered protection scheme. No one layer is perfect, but collectively the protection level is high.

When the wine goes into the bottle, the cork or screw cap seal provide the best level of protection, better than anything prior. We're not opening the bottle until we consume it, so there's no large introduction of contaminants.

While I haven't read this, I'm thinking one value of bulk aging with periodic doses of SO2 is that the duration provides more time for the SO2 to eliminate existing threats, so when the wine goes into the bottle the contaminant level is as low as is possible. It's a normally successful trade-off vs. the dangers of bulk aging. I have no evidence of this, it's just conjecture on my part.

To answer your question as best I can, yes, SO2 can get used up in the bottle. But if the initial contaminant level is low and the SO2 level is high, this will take years.

I do not test for SO2 as I don't see the value. This is not a criticism of those that do SO2 testing -- I believe everyone should do what they feel comfortable with, and besides, my opinion in anyone else's winery means nothing more than they choose to allow it mean. I add 1/4 tsp K-meta / 5 gallons at every racking, and at bottling. My SO2 levels are probably higher than most, but no one (so far) has every complained so I keep doing what I do.

@Rice_Guy posted in the last day or 2, commenting that he maxes SO2 on his fruit wines This makes sense to me, as my experience with organic wineries that use no sulfite is their wines have a crappy shelf life. If you or someone you know has sulfite sensitivity, go light on the K-meta, otherwise don't.


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## Ajmassa (Apr 23, 2021)

Raptor99 said:


> I wonder about this. Do you uncork your bottles every 3 months and add Kmeta? If the carboy is sealed with very little headspace, why would you need to open it and add Kmeta every 3 months? On a percentage basis, the air in a carboy is less than in a bottle of wine. If you seal it with a cork or a cap, and it doesn't leak, I don't see why you would need to open it and add Kmeta.



there’s a lot of variables involved with this- as you can see from all the info given after your post ——- BUT

that every 3 months thing sorta goes hand in hand with racking. with the idea that as sediment drops you rack off and add so2 about every 3-4 months. but if you aren’t racking then it’s less of a big deal. if it goes like 6 months or more in bulk without racking i’ll add some. especially if ph is on high side. And FWIW I’ve also had wine age perfectly fine for years without any so2 added at any point.


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## Rice_Guy (Apr 23, 2021)

winemaker81 said:


> @Raptor99, expanding what @cmason1957 said, the SO2 gets used up. It works by combining with contaminants, so over time the SO2 level is reduced. Given the relative leakiness of any winemaking container with respect to corks, contaminants are introduced to the wine.


* My opinion at present is that new rubber corks can be trusted for”normal” storage, cork closures leak and the Nomacork synthetic closures are doctored to mimic natural oxygen leakage.
* SO is “used up” in a circular reaction which reduces higher redox potential molecules 
* contaminants, at least the bad contaminants are metal ions, they act as catalysts which oxidize molecules.
* a wine must is an organic molecule mix which contains fairly high energy reduced molecules (ex sugar), ethyl alcohol also contains significant energy. Adding SO2 to our wine delays the oxidation reactions however it is like a wallet when we spend a reduced molecule we can’t get it back.



Rice_Guy said:


> This post evaluates ten webinars,, “BOOK REVIEWs” related to air exposure (AKA redox potential) while making wine. Negative as well as favorable quality changes are described for introduced oxygen. The selections are intended to present info about how and why flavors changes and what industry does (home winemakers could consider) to improve quality. Again _ ~OPINIONs~ are in italic, _followed by the link to the specific webinar and any description from the author.
> Australian Wine Research Institute (AWRI) is a neutral research group working on techniques to improve wine, Scott Labs is a technology provider to US wineries (Bucher Vaslin has a European industiral view) and Nomacorc (Vinventions) sells world wide a series of oxygen controled synthetic corks that can mimic natural cork as well as tight metal closures. The last two videos are intended to hint at reductive vs oxidative flavor unfortunately it would be easier just tasting samples so they are last.
> My take on all this; first of all the chemistry starts looking the same no matter if I look in the States or Australia or Europe. Lots of folks believe this is what wine does. Second when folks start analyzing specific chemical constituents they can track back to the air exposure on the juice press and see the rate of chemistry change is faster with early and with more air exposure. Third would be that there is conversion of what we monitor ie poor treatment increases free SO2 consumption, and measured redox potential rate of change and Dissolved Oxygen rate of change and NomaSence oxygen rate of change, ,, the tools we have could be used to understand how big the process risk is in your or my winery. A final point several presenters say is that early winery processes are more important than what kind of closure is on the bottle.
> Several of the arguments given are 1) for red wine micro-oxidation should be done, AKA the 10,000 gallon chemistry similar to treating wine in a barrel is a possible technique to improve quality, 2) there are negatives to any oxygen in that the maximum shelf life of the wine is reduced, 3) for commercial folks it is sometimes worth while to reduce ALL air exposure starting with nitrogen in the fruit press. * Oxidative conditions (lots of air) can be used to develop deep color, non-primary fruit flavor and textural complexity * Reductive conditions (flush everything with inert gas) will maximize fresh fruit flavors along with lower temperatures, inert gas and more SO2.
> ...


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## heatherd (Apr 23, 2021)

I don't rack every three months, but I do add kmeta every three months to my carboy.


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## winemaker81 (Apr 23, 2021)

@Rice_Guy, you exceeded my memory of Chem 101 ....  



heatherd said:


> I don't rack every three months, but I do add kmeta every three months to my carboy.


I was adamant about racking every 3 months ... but based upon feedback here at WMT, I'm not necessarily doing it. If there is only fine lees, I agree, it doesn't appear necessary. I'm keeping an eye on things, as old habits die hard. But old dogs can learn new tricks.


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## heatherd (Apr 23, 2021)

winemaker81 said:


> @Rice_Guy, you exceeded my memory of Chem 101 ....
> 
> 
> I was adamant about racking every 3 months ... but based upon feedback here at WMT, I'm not necessarily doing it. If there is only fine lees, I agree, it doesn't appear necessary. I'm keeping an eye on things, as old habits die hard. But old dogs can learn new tricks.


I felt pretty negligent until @NorCal and others visited with some commercial wine makers who said that home wine makers tend to over-rack.


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## winemaker81 (Apr 23, 2021)

heatherd said:


> I felt pretty negligent until @NorCal and others visited with some commercial wine makers who said that home wine makers tend to over-rack.


Talking to numerous commercial winery owners can be an eye-opener. Home winemakers, as a group, are under-educated and overly paranoid. I count myself in this group, although I try to keep an open mind which is open to learning. Some of our discussions in the past year have been eye-opening.


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## Cynewulf (Apr 23, 2021)

There’s a quote I like from one of my favorite winemakers, Matthieu Lapierre, who refers to SO2 as a fire extinguisher: something he wants to have on hand if things go wrong but hopes he doesn’t have to use. Others prefer a proactive/preventative approach. It’s risk tolerance and I reckon everyone has to go with what they’re most comfortable with. Terroir and Technique in Beaujolais: Talking Natural Wines with Mathieu Lapierre | Wine Spectator


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## sour_grapes (Apr 24, 2021)

Raptor99 said:


> I wonder about this. Do you uncork your bottles every 3 months and add Kmeta? If the carboy is sealed with very little headspace, why would you need to open it and add Kmeta every 3 months? On a percentage basis, the air in a carboy is less than in a bottle of wine. If you seal it with a cork or a cap, and it doesn't leak, I don't see why you would need to open it and add Kmeta.



Wait, most of us age with an AIRLOCK, not a solid bung. You are aware that oxygen may diffuse through water, right? The water may slow it down, but it does not stop it. Nothing like a cork.


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## Old Corker (Apr 26, 2021)

sour_grapes said:


> Wait, most of us age with an AIRLOCK, not a solid bung. You are aware that oxygen may diffuse through water, right? The water may slow it down, but it does not stop it. Nothing like a cork.


I have moved away from aging with an airlock. I either read it here or dreamed it. I have two batches aging with plastic wrap secured with electrical tape. I assume very little air is making through that. Am I missing some sort of aging magic by not letting a small amount of air in?


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## winemaker81 (Apr 26, 2021)

Old Corker said:


> I have moved away from aging with an airlock. I either read it here or dreamed it. I have two batches aging with plastic wrap secured with electrical tape. I assume very little air is making through that. Am I missing some sort of aging magic by not letting a small amount of air in?


If anything, the reverse -- plastic wrap is not necessarily a good barrier. I use vented bungs which let gases out but not in.


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## Old Corker (Apr 26, 2021)

winemaker81 said:


> If anything, the reverse -- plastic wrap is not necessarily a good barrier. I use vented bungs which let gases out but not in.


I know that it is not letting CO2 out but this wine was 6 months old when I removed the airlocks. Degassed, and clear. Is there a reason I should replace it with a vented bung? Or am I just fooling myself when I think of plastic wrap as a air barrier?


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## winemaker81 (Apr 26, 2021)

Old Corker said:


> Or am I just fooling myself when I think of plastic wrap as a air barrier?


I seem to recall someone posting about plastic wrap being a poor barrier, but can't locate the reference.

For the cost of a vented bung ($6 USD), protect your investment in the wine.


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## sour_grapes (Apr 26, 2021)

Old Corker said:


> Or am I just fooling myself when I think of plastic wrap as a air barrier?



Yes, I believe this is the problem, not a good oxygen barrier. Perhaps @Rice_Guy will quantify!


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## Rice_Guy (Apr 27, 2021)

* a typical food plant barrier is a co-extruded plastic composite. It will contain an inner layer as polyethylene which has a low melt temperature and makes an excellent positive seal against glass or PET or metal or HDPE etc etc. There will be other layers which add other properties as oil resistance, oxygen resistance, solvent resistance, CO2 resistance. One of the best barriers is aluminum ie a metalized film or deposited silicate (transparent retorted pouch), both have oxygen transmission rates which are close to zero. All deposited films will have pin holes and we can get away from this by using a thicker layer as aluminum on a ketchup seal.
* Saran is one of the plastic wraps, it is not a good oxygen barrier, it is thin which means the extrusion defects become obvious. On the positive side Saran Wrap stretches therefore we can make a good seal against glass or PET carboys and the mouth is small, another factor is that in aging wine we typically have CO2 which helps protect the wine so all in all Saran isn’t too bad. I wouldn’t use electrical tape to hold it, I would use a rubber band or two.
* silicone is another choice to seal the carboy, your hardware store may have 2” wide rolls of fusion tape (SharkBite underground wrap) or there are cup and bowl covers.


For long term secondary storage with a big mouth bubbler carboy I have placed a saucer over the silicone.
* rubber corks are a good seal for a year or three (old rubber is hard)! This vacuum set up has been running for three months (Feb 11) and dropped from 17.5 in Hg to 9.5 (today),, ask me after a year how well cork and silicone and VacuVin check valve work for sealing a carboy. ,,, (no product in flask)


* driving force is part of storage, my feeling is CO2 is our friend. A 6.5 gallon sister carboy to the above picture of degassed (able to maintain five inches Hg 30 minutes) cyser held a vacuum for a month, ,, likely still had some CO2 bleeding out which equalized the vacuum. On the theory that the ullage is CO2  at equal pressure (no driving force) I consider it safe storage until it is opened up. I kind laugh at folks that want squeaky clean wine with no gas. As noted in other threads I will vacuum cork (like industry folks) and leave some residual gas so the ullage can get filled up with CO2.
* ALL CLOSURES WILL LEAK! some, a metal cap can be rated at 0.1 mg versus natural cork at 4 to. 8.0 mg oxygen per year. ,,, however we can assume the glass carboy or stainless tank walls don’t leak.
* for industrial scale wine the bottling operation is the biggest risk with a typical pick up of 4 to 8 mg O2 per liter, racking to remove SO2 can also be 4 to 8 mg, ,,, home wine makers have larger air to volume therefore we see high risk every time we open up a carboy.
*




Old Corker said:


> I know that it is not letting CO2 out but this wine was 6 months old when I removed the airlocks. Degassed, and clear. Is there a reason I should replace it with a vented bung? Or am I just fooling myself when I think of plastic wrap as a air barrier?


 plus @winemaker81 and @sour_grapes


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## Cynewulf (Apr 27, 2021)

Rice_Guy said:


> View attachment 73907


This may be slightly off topic for this conversation but how does mechanical harvesting decrease oxidative risk? I would have guessed the opposite.


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## Rice_Guy (Apr 27, 2021)

Not really off topic since oxidation is a cumulative effect, ,,, ie you can spend your redox potential early or later in the life of the beverage. The theory on mechanical harvesting

is that it is faster per acre of vines picked therefore one transitions to a low surface area per gallon of juice quickly. Hand pinking for a few hours into a tote squashes juice but doesn’t push all the air out.
Reductive wines do tricks as nitrogen flush the press and tanks, ,,, home can’t 


Cynewulf said:


> This may be slightly off topic for this conversation but how does mechanical harvesting decrease oxidative risk? I would have guessed the opposite.


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## Cynewulf (Apr 27, 2021)

Rice_Guy said:


> Not really off topic since oxidation is a cumulative effect, ,,, ie you can spend your redox potential early or later in the life of the beverage. The theory on mechanical harvestingView attachment 73910
> 
> is that it is faster per acre of vines picked therefore one transitions to a low surface area per gallon of juice quickly. Hand pinking for a few hours into a tote squashes juice but doesn’t push all the air out.
> Reductive wines do tricks as nitrogen flush the press and tanks, ,,, home can’t


That’s kind of what I suspected: the ability to get the grapes into the processing facility more quickly is thought to make up for any damage to the clusters from the harvester. Thanks again - helpful and informative as always.


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## Steve Wargo (Apr 28, 2021)

I put my carboys in the ageing room. It's a large cooled room with 12 foot high ceilings. To close off the carboys when I start ageing the wine; that's after the wine is fully degassed in the carboy. I put a balloon in the neck of the carboy. Then fill the balloon with helium gas till the balloon is pressing real tight against the inside of the carboy neck. That blocks any outside air from getting into the carboy. I tie off the balloon real tight so as not to lose any of that helium gas in the balloon. This works really good. The only issue I have with this technique is figuring out how to get the carboys down from the ceiling when it's time to bottle.  Gotta have fun making wine.


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