Oxygen and/or aeration

[Shemagra]

Do folks aerate or oxygenate prior to yeast pitch or at the start of fermentation? I searched threads here, but only came up with topics related to later steps of the winemaking process.

 

[E.E.B.]

It is not normally necessary, the must usually contains enough oxygen to allow normal activity of the yeast. There are sources that recommend aerating the wine after the brix has dropped by half.

 

[winemaker81]

I've never heard of aerating prior to fermentation. Stirring daily during fermentation introduces fresh O2, as well as preventing any cap for settling long enough to grow mold.

 

[cmason1957]

Aerating prior to fermentation is somewhat expected for beer. (Seal up that fermenting bucket, don't even look at it until 2 weeks has passed, it might catch something.)

Since wine is much lower Ph to start with, we are a bit more tolerant of open (or lightly covered) fermenters. and I agree with Bryan, since we generally stir daily or more often extra oxygen isn't required.

 

[Shemagra]

Aerating prior to fermentation is somewhat expected for beer. (Seal up that fermenting bucket, don't even look at it until 2 weeks has passed, it might catch something.)

Since wine is much lower Ph to start with, we are a bit more tolerant of open (or lightly covered) fermenters. and I agree with Bryan, since we generally stir daily or more often extra oxygen isn't required.

I see that for ferments with grapes, what about a white wine kit with just juice. Should I be stirring? Just leave the ferment open until activity ramps? I am monitoring gravity with a tilt, so I need to sample or open anything up.

 

[winemaker81]

I see that for ferments with grapes, what about a white wine kit with just juice. Should I be stirring? Just leave the ferment open until activity ramps? I am monitoring gravity with a tilt, so I need to sample or open anything up.

Stir all wines.

 

[cmason1957]

I have made some white wines that I wanted to be sure to keep as much floral notes in as possible. With those, I tend to make sure I get lots of oxygen in to start with, then lock down, chill down (60F or lower), and not open for 2 weeks, sort of like a beer. Not from fear of infection, but to keep as much goodness from being blown off as I can.

Reds are nearly always open top, covered with a towel or the brute trash can lid, nothing more, stir twice or thrice per day. I don't monitor the sg daily on anything. Reds are easy to see if they are fermenting and whites generally do quite fine as well.

 

[Rice_Guy]

Many wines are done in a wide mouth bucket covered with a cloth. ,,, ie it wouldn’t do anything extra
In a white or a mead there are recipes that have one use an air lock or restrict air. In this case added oxygen has value since yeast need it to produce new cells. ,,, BUT yeast reproduction is done by the time half the sugar is metabolized. Once yeast stop needing oxygen we get into chemistry’s with oxidation. On my part I try to have everything in a carboy with airlock by 1.030 or 1.020.

 

[Jim Welch]

Do folks aerate or oxygenate prior to yeast pitch or at the start of fermentation? I searched threads here, but only came up with topics related to later steps of the winemaking process.

I oxygenate, three times actually. First immediately before pitching then 12 hours later and once more 12 hours after the second. It isn’t required per se and I’d not recommend buying an oxygenation setup but if one has one, as I did coming to vintning from brewing, it won’t hurt as long as one doesn’t over oxygenate.

 

[Jusatele]

I agree with Jim Welch, I already had the setup so I do
but if I do not have any oxygen, then I do not. I think stirring the must does it though

 

[winemaker81]

One of the most difficult things about winemaking for beginners to understand is that there are multiple paths through the process, and seemingly contradictory advice can all be correct.

 

[BarrelMonkey]

I see that for ferments with grapes, what about a white wine kit with just juice. Should I be stirring? Just leave the ferment open until activity ramps? I am monitoring gravity with a tilt, so I need to sample or open anything up.

Agree with @cmason1957 , for white juice ferments I would do it in a closed vessel (with fermentation bung and sufficient headspace of course!) and try to keep temperature on the lower side to preserve aromatics. I don't think oxygen should be a limiting factor but you could consider stirring if it looks like it's slowing down too early or stuck.

But I do measure brix and temp daily... if there is a problem with my ferment, the sooner I know about it the sooner I can take remedial action.

The only time I vigorously aerate is if I'm building a tirage culture for sparkling wine. Those yeast have enough to contend with (low pH, high alcohol) so I try to kep them well fed and aerated.

 

[Shemagra]

I already have an 02 tank and aeration stone, so gave my current batch a small dose of o2 24hrs after pitching as I'm still in the lag phase. Still leaving a loose cover over it for now. Not stirring. Partially because the cooling coil makes that a pain in the neck.

I appreciate the different responses and perspectives. It's why fermenting things is likely to remain a fun puzzle, as is baking, bbq, etc.

 

[E.E.B.]

Just keep in mind winemakers use different terms than brewers.

 

[Cap Puncher]

I already have an 02 tank and aeration stone, so gave my current batch a small dose of o2 24hrs after pitching as I'm still in the lag phase. Still leaving a loose cover over it for now. Not stirring. Partially because the cooling coil makes that a pain in the neck.

I appreciate the different responses and perspectives. It's why fermenting things is likely to remain a fun puzzle, as is baking, bbq, etc.

You should be good with aerating that you did. I agree with others, after crush there is enough O2 in the must, you don’t need to aerate besides stirring (unless you use dry ice during cold soak, then aerate prior to pinching). But 24hrs after pinch is definitely a good time to use the aeration stone.

I use an aerating stone, a 40 gal aquarium pump (air) and a 0.22 micro inline filter (to prevent particles in the air from pumping in). I usually arerate once a day for 1st 3 days of fermentation. I will do a delestage as well ( which can really aerate too). I won’t aerate after 1.050 SG usually(possibly 1.040 depending on the starting SG). One you hit 10% alcohol, yeast stop taking up nutrients.

Also, oxygen can increase nutrient demand in the yeast. Keep that in mind if you are using a low nutrient must. You may need more nutrients.

Also careful with an O2 tank, because with pure oxygen, you can overdose it ( at least I’ve read)

Lastly I only do a very light aeration on whites at the very beginning after I get yeast activity going. Usually only once. White can’t handle it (unless you do a hyperoxygenation on a Riesling or something prior to fermentation).

Good luck!

 

[Shemagra]

My new takeaways from this, which clearly shows I'm a beginner, but perhaps helps another brewer, is the importance of the difference in starting conditions. I listened to a webinar from the AWRI as well: .

Some notes:
1. there seems to be less of a concern of getting the yeast up to max population as fast as possible.
2. The ph of the must helps delay infection (relative to beer). Also, acid levels in wine are maybe more important than beer.
3. Wine making strikes me a little bit like fermenting out a kettle-soured wort. Lag times, ferment times, etc. are dials on the flavor/characteristic wheel that have many successful settings.
4. Related, a longer lag time or slow ferment isn't the risk it is with beer.
5. The AWRI webinar cites quick ferment times as a benefit and a mixed bag on flavors. That strikes me as an wine industry profit issue, not a product issue. I've found that if the industry does it for profit, it usually is good to take the other side and be "wasteful" for a better product.\

Still ruminating on the yeast nutrient adds recommended later in the primary (halfway through?). My first thought is that I've already maxed the yeast count, so why would I feed them. I guess wine ferments really stress out the yeast and they need it to finish? In beer it's like creating an environment to spring load a growth to max population. In wine it seems like an ultra marathon for yeast where they need way stations to keep their strength up? The products of their exertions are additive or at least a flavor contributor (neither positive or negative) to the final product (relative to beer where byproducts from yeast stress is a negative aspect).

 

[Rice_Guy]

In wine it seems like an ultra marathon for yeast where they need way stations to keep their strength up? The products of their exertions are additive or at least a flavor contributor (neither positive or negative) to the final product (relative to beer where byproducts from yeast stress is a negative aspect).

Additive exertion is a good point of view, I like to say it is like building a fence,, How high does one build their fence?

If I was in the micro lab I could find all the organisms which are likely to grow.
If I select against pH, ,, families that produce toxins won’t grow below 4.0, — another selection is does the metabolism require oxygen or require anaerobic conditions or it doesn’t matter, — how many ppm of SO2 will the organisms tolerate?, — what kind of carbon source will it metabolize?, — what percentage alcohol will the organism tolerate?, ,,,, like a fence each effect is additive so at 6% ABV/ pH 5 (ie beer) it takes more barriers than at 0% ABV/ pH 2.5 (ie sodas) to control growth,

Byproducts are always a negative to growth. BUT another organism in the system may have a pathway to use the excrement from organism one.

To complicate everything food quality has to layer in that chemistry still will happen if micro growth doesn’t. With wine (12% ABV solutions) in the end chemical reactions determine shelf life.

 

[Jusatele]

One of the most difficult things about winemaking for beginners to understand is that there are multiple paths through the process, and seemingly contradictory advice can all be correct.

I think that is why there are so many styles of wine