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Squatchy
10-13-2015, 11:20 PM
So there is always talk about how much to aerate in the beggining of fermentation.

I was reading and found some info. In the article it says 10% alcohol is the turning point in which yeast no longer can use oxygen as a nutrient. So in a nut shell I believe we should aerate our mead up to the 10% point. This is also (10%) the point at which DAP is no longer used by yeast as well. Coincidence? I doubt it but I don't have enough science under my belt to tie the two together, yet :)

Here is a quote

Red wine: 5/10 mg/L at: 1) the start of fermentation, 2) the
day after, and 3) maybe in the following days if needed*.
With each addition you are looking to see a strong decline in
the sharp and stinky negative VSCís. The wine should be noticeably
fresher in aroma and flavor when you finish each
treatment.
White wine: 5 mg/L at: 1) the start of active fermentation.
At this stage, the wine does not oxidize as the yeast will take
up the oxygen before it can react with the must. The wine
should become noticeably softer and rounder after the dosage.

* It is important to note that while the above dosage rates are safe,
they are being prescribed at the early, more active stages of the fermentation.
Direct additions of oxygen are usually not recommended
after the must has reached 10į alcohol. This is because in the early
stages of fermentation, yeast take up oxygen as a nutrient, and they
do this quickly. However, after 10% alcohol, they no longer uptake
nutrients (oxygen as well), so whole dose impacts on the wine matrix
itself.


This is a link for the entire article if anyone should care to read it. http://morewinemaking.com/public/pdf/oxyfer09.pdf

JewishMonk
10-14-2015, 01:51 AM
Thank you, Squatchy. That's a valuable bit of info. It's good to have a more concrete milestone than just "the first few days".

pokerfacepablo
10-14-2015, 02:23 AM
This article is for wine not mead. But it does hold water... I see that you already know that. That's why you don't place an airlock for the first 1-2 weeks with wine. I wouldn't chance it with mead though for fear of the cardboard taste. As long as you're stirring and not aerating past the 1/3 break, you shouldn't have any issues with the yeasties. I stir sometimes up to 10 days after fermentation started. A lot of people do an open ferment for the first 1/3. If you can find an article that states mead in particular, please post the link.

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kalvaer
10-14-2015, 07:40 AM
That's why you don't place an airlock for the first 1-2 weeks with wine. I wouldn't chance it with mead though for fear of the cardboard taste. I've been thinking about this a quite a bit recently as it does not make sense to me, the whole "leave it open to get O2 in"? And this thread got me thinking again.

CO2 is heavier than O2. As the yeast starts producing CO2 in a carboy or bucket, it will slowly start displacing the O2, and creates a protective layer of CO2 which helps to stop oxidation, and also why the fruit floating on the surface does not rot. As long as there is no flowing air to push this CO2 away, it will happily stay where it is, especially during the primary fermentation when the yeast is actively replacing the CO2. This is even more true for those of use who brew small batches in carboys and buckets with mostly sealed lids or bungs with small holes. (I would more be worried about some rogue fly coming to taste my brew and infecting it)

Now once the primary fermentation has started slowing down, it would make sense to then seal it off to stop the O2 from slowly defusing back into this protective layer, especially if yeast no longer actively consumes O2 after 10%.
While the above article might be regarding wine, it was also specifically related to yeast. Since we all use the same yeasts, would they act differently in one medium or another?

Stasis
10-14-2015, 07:53 AM
In the article it says 10% alcohol is the turning point in which yeast no longer can use oxygen as a nutrient. So in a nut shell I believe we should aerate our mead up to the 10% point. This is also (10%) the point at which DAP is no longer used by yeast as well.

Nutrients could not be used after the 9% abv mark. However, even below 9% the yeast might not fully use all the nutrients you provided even if they should need it. This is why nutrients should still be provided well before the 9% abv point. To quote Medsen:
"So you are fine adding DAP up to 5% ABV and can be confident that it will be utilized. Above 5% ABV the uptake of DAP drops off a cliff, and beyond 9-10% none is being used."
I'd add nutrients up to the 4% point just to be on the safe side, especially since the test was on only a single strain of yeast. In an average 12% abv mead this is the 1/3 sugar break.

If the same interactions happen with the use of oxygen you might also want to aerate until the 4%abv mark or roughly the 1/3 sugar break. This is because even though the yeast might use some of that oxygen, another part might not be used and could end up helping oxidation.
This is probably not such a large issue with mead, but it might still be good practice to play it safe

Squatchy
11-15-2015, 07:53 PM
Nutrients could not be used after the 9% abv mark. However, even below 9% the yeast might not fully use all the nutrients you provided even if they should need it. This is why nutrients should still be provided well before the 9% abv point. To quote Medsen:
"So you are fine adding DAP up to 5% ABV and can be confident that it will be utilized. Above 5% ABV the uptake of DAP drops off a cliff, and beyond 9-10% none is being used."
I'd add nutrients up to the 4% point just to be on the safe side, especially since the test was on only a single strain of yeast. In an average 12% abv mead this is the 1/3 sugar break.

If the same interactions happen with the use of oxygen you might also want to aerate until the 4%abv mark or roughly the 1/3 sugar break. This is because even though the yeast might use some of that oxygen, another part might not be used and could end up helping oxidation.
This is probably not such a large issue with mead, but it might still be good practice to play it safe

Hi Stasis

I was thinking of you when I read this last night in the Cider Handbook by Scott Labratories.

In a different thread we talked about splash racking, transfer of must/mead by poring through a funnel ect. I couldn't find that thread so I came to this one which was very close in nature. On page 12 of the cider handbook I copied this to paste here.

Oxygen
Many cider producers might think oxygen is their worst nightmare. Though
oxidation of the finished product is never desired, active fermentations greatly
benefit from oxygen introductions. A small amount of air should be introduced
into the fermentation 18-24 hours after yeast inoculation. It is during this
period of exponential yeast cell reproduction that the newly produced yeast
population needs oxygen to produce the lipids in their cell membrane. Strong
membranes will protect the yeast at the end of the alcoholic fermentation
from the toxic effects of elevated temperatures and ethanol. Without
these lipids the cell membrane becomes leaky and the yeast cell transport
systems are compromised. Yeast are excellent oxygen scavengers and will
remove all oxygen before any oxidation problems can occur to the juice. Air
can be introduced by racking, leaving the air lock off for 24 hours or by venturi
device. Oxygen additions should not continue past the halfway point of your
fermentation.

Would you read this to say that the yeast will "clean up any oxygen" in the must providing none is added after the half way make?

Mazer828
11-16-2015, 02:12 PM
Will no nutrients at all be uptaken after 10%? Even organic nutrients like Fermaid-O or boiled yeast?

Squatchy
11-16-2015, 02:23 PM
Will no nutrients at all be uptaken after 10%? Even organic nutrients like Fermaid-O or boiled yeast?

That is referring to DAP

Mazer828
11-16-2015, 03:08 PM
Ah. Ok. Any data on how long organic nutrient additions will be effective?

Squatchy
11-16-2015, 08:26 PM
Not sure what the dead line is but the data sheets say that your last SNA should be at 50% sugar break

Thomas Riisbjerg
11-17-2015, 02:58 AM
Keep in mind that the halfway point in a cider fermentation is typically <5%.