carboy aging

[Mike Parisi]

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.

 

[Raptor99]

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.

 

[cmason1957]

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.

 

[winemaker81]

@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.

 

[Raptor99]

@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.

 

[winemaker81]

@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.

 

[Ajmassa]

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.

 

[Rice_Guy]

@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.

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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This webinar starts with an overview of wine degradation over years of storage and finishes with a review of bottle closures with oxygen transmission data. Of note; at the seven minute point it mentions an article that influenced Australian wineries to favor low oxygen transmission closures. The impact of air in early processes such as long pressing increases dissolved oxygen which increases measured degradation, however one don’t see this till it is bottled, 2) metals are required to catalyze/ speed up wine reactions, 3) data shows the wine chemistry (redox potential) is more important than the type of bottle closure, 4) total oxygen at packaging is more important to shelf life than the closure type. All wines consume oxygen (can become reductive) but how fast?, new closures might scavenge sulfur (reductive) aromas, 43 minutes
www.youtube.com/watch?v=09vejFiudrM * Closures – latest understanding of their impact, Presenter - Dr Eric Wilkes (The_AWRI) 2017 Over the last few decades the range of closures that have become available to the wine industry has increased significantly, along with the claims and counter-claims about their benefits for the storage and maturation of wine. The Australian Wine Research Institute has now conducted numerous closure trials in red, white and even sparkling wines. This webinar will present the current understanding of the impact that closure selection can have on wine development, including the role of oxygen, transition metals and volatile sulfur compound development, and the underlying drivers behind the chemical changes that occur as a wine ages.
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An excellent first look at the effect of oxygen in a wines quality. It covers effects from a wide range of practices as tannin addition , splash racking, dissolved oxygen, temperature effects, gas/ nitrogen flushing and tools as oxygen transmission rate or the redox meter used to find where damage is happening, and what the change means on the finished wine’s flavor. Scott Labs like AWRI point at dissolved oxygen as the main culprit for loss of shelf life. A long video but the explanation to what can be improved; 1 hour, 38 min.
https://www.youtube.com/watch?v=ETuExGmNgzE * The Basics of Oxygen Management to Preserve Wine Quality: We are excited to announce the next episode in our new Scott Labs webinar series hosted by our very own Darren Michaels. Join us for a short presentation and Q&A with special guest speaker Luke Holcombe where we will be discussing the other side of finished wine quality: oxygen management. Topics will include: - What could go wrong? Oxygen-Related Faults - Bottling and Packaging Concerns - Oxygen Management Concepts and Techniques
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This is a second look at oxygen exposure and risk analysis, again excellent. I found it interesting to have data which gave examples of what level of oxygen could be picked up in processes as racking or with a variety of closure types. I lust for one of the DO meters pictured. A final theme- we can extend wine quality into years by fixing at how much life we lose early in the winery processes. 1 hour, 7 minutes
https://www.youtube.com/watch?v=sn7Lxq4ynN4 * Dissolved Oxygen: Why it’s Important and how to Implement a Management Program: Luke Holcombe, Scott Labs Field Sales Rep., Dissolved oxygen is the driver behind many of the most common stability and spoilage issues facing winemakers. Its negative synergistic relationship with sulfur dioxide, the role it plays with volatile sulfur defects, and microbial interactions make it worthy of attention. In this webinar, we will discuss its effects, easy to implement mitigation and removal strategies, and discuss “bottle shock” as well as “barrel shock”.
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This video is about half chemistry and half treatments which can be tried to change reductive flavors. Ie sulfides / threshold detection level/ latent sulfur changes (in bottle), YAN prevents yeast from forming sulfide compounds, it is easier to flush SO2 out early with yeast CO2.
* Managing ‘reductive’ aromas in wines; Speaker: Dr Marlize Bekker (The Australian Wine Research Institute) Webinar recorded: 7 November 2019 Additional resources: https://www.awri.com.au/industry_supp...
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[heatherd]

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

 

[winemaker81]

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

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.

 

[heatherd]

@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.

 

[winemaker81]

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.

 

[Cynewulf]

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

 

[sour_grapes]

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.

 

[Old Corker]

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?

 

[winemaker81]

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.

 

[Old Corker]

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?

 

[winemaker81]

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.

 

[sour_grapes]

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!

 

[Rice_Guy]

* 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.
*

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