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Vinegard smell at start of Fermentation... Any quick fixes?

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boertjie

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Hi, I have just started a 1300L Sauvignon Blanc fermentation and it almost immediately started giving off a vinegar like odour.

I am hesitant to suspect an infection as I thoroughly cleaned and sanatized everything, including washing the grapes with a meta, tannin and acid solution prior to crush.

Total So2 and Free So2 ended up being a little higher than I had aimed for due to the lingering effects of the pre-wash.

Measurements after crush:
Sugar: 21.3 Brix / PH: 3.41 / TA: 5.54

The juice tasted really good and fresh and I decided to bump the acid up to 7 before innoculation.

This is where I suspect the problem might have come from as I only realised after adding Lactic Acid 80% - that my pump is no longer functioning. This meant that I couldn't properly mix the acid into the wine and I was forced to let it mix naturally.

I left it overnight and then introduced CKS 102 yeast, which is a bit nitrogen hungry... So I made a point of smelling it regularly to try and detect a nitrogen deficiency as soon as it arised. Instead, I almost immediately started picking up a faint apple vinegar like smell, which became more prominent with each checkup.

Is there any chance that this could be the yeast ending up on a pool or concentration of lactic acid?

Any advise would be greatly appreciated as I am desperate not to lose this batch.
 

Tnuscan

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"washing the grapes with a meta, tannin and acid solution prior to crush".

What was the purpose of using this solution?
What kind of acid?
What were the Ratios and how was this applied to the grapes? Was this allowed to dry or was it rinsed afterward?
 

salcoco

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did you add nutrient as proposed. sound like stressed yeast to me
 

ibglowin

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You also mention adding "lactic" acid"? I hope you didn't add that to the must as tartaric is the only acid that should ever be added to a grape must.
 

boertjie

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"washing the grapes with a meta, tannin and acid solution prior to crush".

What was the purpose of using this solution?
What kind of acid?
What were the Ratios and how was this applied to the grapes? Was this allowed to dry or was it rinsed afterward?
Hi, thanks for taking the time... Perhaps pre-wash is a bit misleading. The solution is a commercial product called Oenoprotect (Potassium Metabisulphate (50%) L+ Ascorbic Acid (30%) Oenological Tannin (20%)) which is sprayed over the fruit and crates as they are transported into the cellar via rollers. After the spray they pass under fans which blows off most of the solution.

The purpose of this is to clean the grapes of dust and foreign contaminants whilst inhibiting native yeast and bacteria.
 
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boertjie

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You also mention adding "lactic" acid"? I hope you didn't add that to the must as tartaric is the only acid that should ever be added to a grape must.
Hi, unfortunately that was not a typo... I added Lactic Acid 80% FCC.

Why was this a bad idea?
 

boertjie

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did you add nutrient as proposed. sound like stressed yeast to me
Hi, yes I added DAP, 24 hours after inoculation. The smell appeared almost immediately after fermentation got under way however.
 

stickman

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It seems like you may be referring to acetaldehyde aroma which is sometimes described as rotten apples. You didn't say what your free so2 was before inoculation, but high so2 levels can cause high acetaldehyde production from the yeast.
 

ibglowin

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Yea, most definitely. You should only use tartaric for grape must acid adjustment. While it is certainly an acid and will lower pH and raise TA I have no idea what kind of aroma or off flavor it might be bringing to the fermentation party.

Hi, unfortunately that was not a typo... I added Lactic Acid 80% FCC.

Why was this a bad idea?
 

boertjie

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It seems like you may be referring to acetaldehyde aroma which is sometimes described as rotten apples. You didn't say what your free so2 was before inoculation, but high so2 levels can cause high acetaldehyde production from the yeast.
I must say that this makes the most sense to me so far... As mentioned, the SO2 levels were higher than I intended - 32 free / 68 total. And this specific yeast is know to be sensitive to high levels of SO2, which causes the yeast to also produce SO2, as I understand it...

I assumed those levels, though a bit high would still be ok?

If this is in fact the culprit, do you have any suggestions on saving the fermentation?
 

boertjie

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Yea, most definitely. You should only use tartaric for grape must acid adjustment. While it is certainly an acid and will lower pH and raise TA I have no idea what kind of aroma or off flavor it might be bringing to the fermentation party.
Thanks, this is my first pre-fermentation acidification... We usually only need small adjustments after fermentation and have always used only Lactic Acid for that purpose.

So that is all that I had on hand and didnt consider any negative impacts, to the contrary.

We are in a very hot climate offering quick sugar production with little comparable loss of acids from the fruit before ripeness is achieved. In a rainy season like this one however, that goes out of the window.
 

Tnuscan

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Wouldn't aeration dissipate the so2.? I once used a large aquarium pump to dissipate so2 out of a smaller batch and it worked for me.
 

ibglowin

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I am wondering if the lactic acid is being converted to acetaldehyde via some process/reaction.
 

boertjie

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I am wondering if the lactic acid is being converted to acetaldehyde via some process/reaction.
That was my line of thinking originally in terms of the acid not dissipating into the must and the yeast ending up in a high concentration and converting it into something causing the odour I was detecting.

I have since used a swimming pool pump to pump the must through for about 15 minutes and will check up on it again first thing in the morning.
 

boertjie

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This morning the batch is fermenting like crazy and I am happy to report that I can no longer detect the odour in question. - The pumping seems to have made a major difference, but doesnt really help in terms of figuring this out.

It could have A: Bound enough of the SO2 to allow normal performance from the yeast
B: Dilluted the Lactic enough for that process to become insignificant compared to the normal fermentation
C: Or it could be the DAP taking effect

I am very hesitant to assume the issue has been resolved however and will keep a very close eye on it. Thank you all for your time and advise thus far.

Much appreciated.
 
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