When Are CO Levels Not Enough to Protect Wine?

[robie]

Dont worry about the oxidation so much, the wine is loaded
with C02 and some O2 is good for red wines. Remember that red wines are
stored in barrels for around a year sometimes and the whole time its in
there its getting O2 and thats called micro-oxygenation. White wines and
fruit wines are a different story as they can turn brown a little
easier but even then its still loaded with C02 so a little more time in
primary is ok.

The above quote is from another forum topic. This new topic has been created to further discuss this issue and for the benefit of new wine makers.


Wade,





I understand that at that the secondary fermentation stage there is loads of CO2 still in the wine,
and that there will continue to be until the wine is degassed.



However, I would think that this stage, which
requires the vessel being sealed and locked down with an air lock, would not do well in a
10-gallon bucket, because that lid fits so loose that it wouldn't make a
lot of difference it you left that lid off entirely (from an
oxygenation point of view; not talking about critter entry issues).





If what you say is true, if one is fermenting to dry in any bucket, why
ever bother to snap the lid and add an air lock, other than to keep
critters out and cleanliness? (I know with an open vessel there would
be issues with air currents sucking off CO2, but let's forget about that
sort of thing for this discussion.) I wonder if all of us are not
carrying this potential oxidation issue way too far. I don't think we
are, but what do I really know. I have always been careful, so I have
never had an oxidation issue. As a result, I don't have a feel for when
one reaches that threshold of carrying it too far and too much oxygen.





I spoke with one LHBS owner who said there is no need to ever top off,
even in bulk aging, because there is always so much CO2 left in any home
winemaker's wine that oxygen can't get to the wine, anyway. Of course I
have a hard time accepting that as fact.





I don't know if I am asking a question or just making a statement, but,
since I haven't had an oxidation issue, I don't really know what it all
means.





I guess I would like to have some more discussion on the issue of when
is there not enough CO2 left to protect the wine, requiring a sealed
vessel with an air lock.

 

[JimCook]

I think the match test is a quick and dirty way of seeing if oxygen can get to your wine. If a match can burn, there's oxygen present. If it goes out, there's not much oxygen there. Even with an airlock, oxygen can still get into your storage vessel (one of the reasons to top up).




Does this mean you have to enclose your winemaking zone in some kind of 'contain E.T.' plastic bubble? No. The longer you plan on holding onto your wines before drinking them, the more important oxygen exposure becomes. If you consume an entire kit wine after only six months of age, for instance, then I doubt that you'll see an oxidized bottle if you follow reasonable oxygen protection methods.


During the rapid bubbling of secondary fermentation, the CO2 gas is pouring off. As the wine approaches dryness, the rate of release of the CO2 gas is lessened and like a salmon swimming up current, the wine at the top of the fermentation vessel is subject to contact with oxygen molecules. The more CO2 gas coming out, the greater the current, and the converse is also true.


As Wade had pointed out in the post that spawned this one, whites and lighter fruit wines can be much more susceptible to oxidation. At the same time, it's important to note your own personal consumption habits. This week, I opened a 3-year old bottle of kit Chardonnayand it looked beautiful with a great golden color and no sign of browning or presentation of age-related off odors. When I made the kit, I did not snap any lids down and while I used an airlock, this kit was degassed and aged in glass almost a year before bottling.


- Jim

 

[robie]

When I made the kit, I did not snap any lids down and while I used an airlock, this kit was degassed and aged in glass almost a year before bottling.

If you did not snap the lid down, what good was putting in an air lock?

There is a big difference in how tightly the lid on a 7.9 gallon fermentation bucket seals or even rests, versus the lid on a 10-gallon "trashcan-style" bucket.

So Jim and Wade,
For reds, do you (or anyone else out there) think fermenting until dry in a trashcan-style bucket is a good idea?

It just seems to me that if your answer is yes, for reds and under normal circumstances there should not be any real concern for oxidation until AFTER degassing. Of course this assumes one is not totally irresponsible in how one subjects the wine to air.

I know I am probably beating a dead horse, but I just want to know, yes or no, if I can safely ferment a red all the way to dry in a trashcan-style bucket. I personally don't think it's safe.

 

[vcasey]

I know I am probably beating a dead horse, but I just want to know, yes or no, if I can safely ferment a red all the way to dry in a trashcan-style bucket. I personally don't think it's safe.

Yes I do all the time and have NEVER had a problem. The only time I think there would be a problem is if the wine was fermenting slowly (longer then 14 days), then I would be inclined to move it to glass.
Keep in mind there really is no all right or all wrong way. As long as you are happy with how you are handling your wine making and you enjoy your wines - you are doing everything right.

 

[grapeman]

I always move my wines of all types over to a "sealed" container at about 7-12 days, even the ones fermenting in trashcan style fermenters or even Brutes. To me it is an issue, especially with reds that I don't want to go under malolactic fermentation. My winery has been exposed to thsoe bacteria so if they are unsealed, they will go through mlf. This is true until they have been sealed up or a good dose of k-meta applied.


In response to vcasey, I don't believe that any wine is truly dry at 14 days or less, so I move all of them a while before.


Regardless, we all have our own ways of doing things. Are any right or wron? If your wine turns out great, then you are doing it YOUR right way. If the wine makes you squirm, wiggle and spit it out when you taste it, then maybe you should change your method.

 

[robie]

Thanks all,

I do like to ferment to dry in the same bucket, so if I can get away with not having to move to a carboy for secondary, I'd just as soon not do it.

 

[Wade E]

I believe appleman said it all but must say Ive had pretty high gravity wines ferment to bone dry in less then 14 days with normal temps but have also had wines take much much longer also. If its one of those long drawn out fermentations like a mead then by all means get it into a carboy.

 

[JimCook]

If you did not snap the lid down, what good was putting in an air lock?

I actually do put an airlock in the lids even if I don't snap them down (one less hole for bugs to get in through) although I was actually referring to using an airlock during secondary fermentation and bulk aging periods.


- Jim

 

[Bartman]

I have never had a problem with oxidation, even when I didn't know it was an issue, and therefore did nothing to prevent it (other than follow the kit instructions). I'm almost tempted to purposely allow a kit to oxidize to see the effects and the speed in which it happens; unfortunately, I do not have an extra $75 to blow on an experiment in "ruining" a wine.

That said, I think Dancerman is over-thinking it or worrying about an issue that is, at worst, a slight to minuscule risk of total loss, and at best(?), a low-moderate risk of "damage" to the finished wine. Unless you totally neglect your fermenting wine and leave for 20 days+ in the primary, I doubt it will be a real issue. If the primary is in a still/no air draft room, it seems possible that the CO2 will lie still over the wine protecting it from most O2 for some time. Even though CO2 and O2 are miscible gases (unlike oil and water), CO2 is heavier so it should sink below the O2 in a perfect vacuum/sealed system (who doesn't ferment their wine under those conditions?)

 

[robie]

Thanks for your input, Bart,

I don't really think I am over thinking the issue (this time - ha!). I am an engineer; what I am (was) looking for is a definitive answer to the problems discussed. Are we overly protective concerning oxidation or are we not? Can we safely leave wine to ferment to dry in a trashcan-style fermentor bucket that doesn't really seal or can't we?

To tell the truth, I didn't get a definitive answer, but I got what I needed. The reason why I started this issue as a separate topic was to hopefully help newbies as they come along and wonder about this issue. I wonder if anything discussed here will be of help to them.

Yes, it would be interesting to see what it would take to get a kit to come out oxidized. Maybe we should all pass the hat and assign someone to trash a perfectly good wine kit, just to satisfy our curiosity.

Nah!

Thanks again for everyone's input.

 

[harryjpowell]

Bart,
You could take a sample, say 1/2 gal into a 1 gal jug and let that oxidize and compare the result with the rest of your kit. A bit of effort but I'd guess you would come to a much better trained taste of the oxidation effect on your wines.

 

[barryjo]

Trash an entire kit???? Why not just use half of it for the experiment and finish the rest normally???
Of course, for those who brew 60-70 gallons a year, what is one kit, more or less?

 

[PeterZ]

What follows is my opinion.


Yes, you can ferment to dry, and then some, in a 10 gallon trashcan type fermenter, as long as you can resist opening the lid. While the lid doesn't seal like the 7.9 gallon fermenter does, it provides sufficient sealing that the blanket of CO2 from primary fermentation will remain over the wine, blocking any O2 that may get in.


The largest factor in air introduction in a vessel under airlock or with a loose fitting lid after fermentation is changes in atmospheric pressure. The change from hurricane low to clear high is about 3%, so you could introduce 3% air into the vessel. Air is only 20% O2, so the potential O2 introduction is 0.6%.


At the same time the wine is still supersaturated with CO2. That makes the introduction of any other gas very difficult. The <1% O2 in the headspace is just not an issue.


From a practical standpoint, I generally put about a quart of wine in a 1/2 gallon jug when transferring to secondary to leave headspace in the carboy to avoid the dreded wine volcano. The result is wine about 4" deep with a 6" diameter exposed surface. I have left this for months under airlock with no sign of oxidation.


Basically, using reasonable care, I believe oxidation of a wine that has not been degassed is just not something to worry about. Oxidation only becomes an issue once the wine is degassed completely. At that point I think topping up is necessary if you are going to hold a white in bulk for more than a couple of weeks, or a red for more than a couple of months.

 

[Wade E]

As I dont know all the stuff the Peter does I do know that we really worry way too much about oxidation. I almost always ferment to dry in bucket and have never had a problem doing so and I believe doing it this way for 1 makes it much easier to degas the wine and 2 helps it to ferment dryer as every bit f yeast is still in there and none is left behind from a transfer.

 

[Chef]

I'm a "newbie" and I have to say that this threadhas been very infomative!! I have been reading through this forum for about a week now and have gotten more tips, techniques, and pure knowledge, than my brain is able to filter...The problems I wasrunning intois that most of the directions/recipes dont always give true step-by-step directions so someone like myself "newbie" find it very easy to do something stupid...like not degass wine and wonder why it doesnt taste as good as everyone elses...

... Sorry for the long useless speel...just wanted to say thanks to everyone that posts and discusses everything wine because it really does help us "newbies".

 

[PPBart]

As I dont know all the stuff the Peter does I do know that we really worry way too much about oxidation. I almost always ferment to dry in bucket and have never had a problem doing so and I believe doing it this way for 1 makes it much easier to degas the wine and 2 helps it to ferment dryer as every bit f yeast is still in there and none is left behind from a transfer.

Good discussion!


For those batches fermenting to dry in primary, do you routinely stir the must to get yeast back into suspension and aid degassing? Would that not encourage O2 absorption? (example that came to mind was Skeeter Pee which is agressively stirred specifically to get O2 into the must).


Personally, I usually will move the batch into carboy when SG gets down to approaching 1.000. I like to see some airlock activity to reassure myself that there's a nice CO2 blanket in place.

 

[robie]

For those batches fermenting to dry in primary, do you routinely stir the must to get yeast back into suspension and aid degassing? Would that not encourage O2 absorption? (example that came to mind was Skeeter Pee which is agressively stirred specifically to get O2 into the must).


Personally, I usually will move the batch into carboy when SG gets down to approaching 1.000. I like to see some airlock activity to reassure myself that there's a nice CO2 blanket in place.

Since this topic was originally posted, I have found out that there are
two stages of fermentation - aerobic and anaerobic. (Here, I am
writing about the true "primary" fermentation which takes place before
any MLF fermentation. Technically speaking, MLF is the true secondary
fermentation.)



During the first (aerobic) stage of fermentation, oxygen is necessary
for the functioning of the yeast. Stirring the must during this stage
is actually a good thing, as it stirs oxygen down into the must. There
is so much CO2 being produced that any slight degassing caused by
stirring, is not an issue; it is replaced in minutes.



During the second (anaerobic) stage, oxygen should be kept from the
fermenting wine. It is the start of this second stage that one should
stop stirring or doing anything that would introduce oxygen into the
wine. Stirring up the yeast is not necessary at this stage. Lots of
CO2 is still being produced but less than during the first stage. When
the instructions say to rack to a secondary container and add an air
lock, it is an indication of the start of this anaerobic stage.



For a fermentor bucket, which doesn't have an airtight lid - In my
opinion, there is so much CO2 being produced that a nice blanket of it
will remain in place during this stage, as long as no heavy stirring or
drastic change (movement or air current) is introduced. With this type
of fermenting bucket, one should always check the SG to determine when
this stage is finished. When it is finished, immediately rack to a carboy with airlock.



So - if you prefer racking to a carboy and air locking, this is the
safest way to prevent oxidation. However, fermenting to dry in a fermentor
bucket, which doesn't have an airtight lid, though technically not as
safe, will also work well, as long as caution is exercised to not excessively introduce oxygen..