Excessive Time in carboy without SO2.

[noofie2]

Back in October/November I made about 6 gals each of Pinot Noir and Cabernet Sauvignon from pressed frozen grapes. They have been sitting in carboys since then. The CS went through ML back then, was racked and SO2 added. However the PN had not gone through ML and I let in sit for 4mos+ without adding SO2. The temperature in the basement is about 60F. I got distracted on some family health issues, tax preparation and the Covid19 issues and forgot the PN not having SO2 addition. I just checked and the CS is fine...I just need to rack it again and continue. But the PN has a problem. In November it tasted ok. Here are my sample notes on it now...
Friday April 3rd 2020
PN in 6gal container
General - Container filled to top. Very clean surface...NO white film or blobs. Surface area very small with very little exposure to air. Air space gassed from N2 cylinder.
Color - very good, clear ruby, no cloudiness
Nose - no adverse smells, fairly pleasant nose, some earthiness, slightly floral, very low on fruit.
Taste - low fruit, low tannin, out of balance, acid quite high...NO vinegar taste or smell however, no spritz, no nail polish taste, no geraniums, somewhat bitter and earthy.
Needs - rack, ML neasurement to see if 2nd fermentation occured over last 4mos, add some SO2, later...improve balance, counteract excess acidity, improve fruit flavors.
My questions are...what do you think is wrong with this wine, is it worth trying to save it...and if so what do you suggest I try?

 

[RPh_Guy]

The problem is excessive acidity, right?

Did you add ML bacteria?
Have you measured TA or pH?

 

[noofie2]

Yes excess acidity but it doesnt taste or smell like acetic. I added ML bacteria back in November before I abandoned the carboy for 4+mos. Before ML bacteria addition, the pH was measured back then by a commercial lab at 3.4, the TA at 0.69g/100ml, the malic acid at 2.37 g/l, VA at 0.033g/100ml and free S02 less than 8ppm. I plan on adding some SO2 tonight and getting it re-tested on monday for all components. I am afraid what I am tasting is acetic acid spoilage even though it doesnt smell like nailpolish or taste like vinegar. FYI the carboy had very little free space and oxygen in it and that small space was purged with nitrogen anyway.

 

[noofie2]

...and the wine didnt taste excessively acidic back in November.

 

[RPh_Guy]

What is the recommended pH for the bacteria culture you added?
The culture was fresh, stored properly (refrigerated, kept air-tight), rehydrated properly, etc?
The wine was at a reasonable temperature for the bacteria to work?

You always have the option to add some potassium carbonate to drop the acidity.

I guess further testing will reveal more about what's going on. Do you send it somewhere for testing?

 

[noofie2]

I remember checking back in November and the ML culture was fine...type, clean, refrigerated, etc. Howver the wine temp was about 65F at the time. Since then it dropped in the winter to 58F. I know that is low but I didnt want to heat it up because of the low SO2. I get testing done at Gusmer Enterprises in Napa. I drive there since I live about 30mins away by car.

 

[noofie2]

If the acid is acetic the potassium carbonate or bicarbonate will not correct for that...right?

 

[RPh_Guy]

If the acid is acetic the potassium carbonate or bicarbonate will not correct for that...right?

Right.

 

[noofie2]

I'll post what I find out from the analysis.

 

[RPh_Guy]

I mean, it won't lower the acetic acid, but lowering the tartaric and/or malic would still make it less sour tasting.

 

[noofie2]

I got the preliminary results back from the lab as follows:
F-SO2 less than 8ppm T-SO2 less than 8ppm VA 5.9g/L pH 3.58 TA 5.5g/L Alcohol 13.9% Glucose 0.77g/L Fructose 0.82g/L Malic acid less than 0.3g/L
This shows an acceptable VA level and that the wine has gone through ML fermentation.
An addition test will be performed by the lab called the "Plate" test that will take another week to get results...hopefully to find out what is causing the sharp and bitter taste.
In the meantime since it has now gone through ML fermentation, I will add SO2 to stabilize and protect the wine more substantially.

RPh Guy ... any more thoughts?

Thanks...Noofie2

 

[RPh_Guy]

VA 5.9g/L

Are you sure you typed this correctly?

This level is definitely excessive. You must have had too much oxygen get to the wine.

 

[noofie2]

Sorry my bad ... it said the ML is 0.059g/100ml which is actually 0.59g/L NOT 5.9g/L. My conversion mistake!!!

 

[noofie2]

Actually it taste a bit better now ... perhaps after being briefly exposed to a little air. I just added S02 to bring it up to about 25ppm. Maybe I can save this PN after all. In a week I'll get the other test results looking for flaws that might be causing that sharp bitter flavor. The lab tech said he saw some bacteria swimming around in the sample.

 

[RPh_Guy]

I will add SO2 to stabilize and protect the wine more substantially.

RPh Guy ... any more thoughts?

There's no explanation for tartness looking at those levels.

Actually it taste a bit better now ... perhaps after being briefly exposed to a little air. I just added S02 to bring it up to about 25ppm.

Not oxygen, acetaldehyde. Acetaldehyde can cause tartness and adding sulfite can help with that by binding to it.

The sharp bitterness may be from oxidation. Some fining agents or tannins may or may not be able to help with that, but I couldn't give any specific recommendations.

 

[noofie2]

Thanks much for your feedback. I'll see what results I get back next week and how adding SO2 might affect the wine's taste and smell.

 

[noofie2]

So today I got the results of the "plate wine spoilage" test for the pinot noir as follows:
Plate wine spoilage 70 CFU/ml 1 um wide straight uniform rods of variable length as single cells, short chains or long filaments.
Presumptive ID Lactobacillus.

I don't know if the 70 CFU/ml level is excessive or not. This is after the wine has gone through ML fermentation. Again the wine has an underlying bitter taste.

 

[noofie2]

I added some SO2 a week ago and the wine still has the same bitter taste.

 

[RPh_Guy]

I don't know if the 70 CFU/ml level is excessive or not.

After pressing fresh fruit, or after pitching an appropriate amount of yeast, there are BILLIONS of CFU/mL. 70 CFU/mL is pretty low.

 

[noofie2]

That's what I thought also...plus the VA level is only 0.59g/l. So its still a mystery... why the excessive bitterness? From the web...."Bitterness in wine can develop from metabolism of glycerol, mainly by Lactobacillus sp. The bitter taste is thought to result from the reaction of red wine phenolics with acrolein (Sponholz 1993). This type of wine spoilage is often referred to as 'amertume' (bitter in French)."
Also you mentioned earlier that acetaldehyde produced by acetic acid bacteria (AAB) could be the problem, where acetaldehyde can cause tartness and adding sulfite can help with that by binding to it. There is another test for the acetaldehyde level ($60)....but I'm not sure if it makes sense. RPh Guy...what do you think?
So at this point I tentatively plan on adding some more SO2...perhaps up to 35ppm F-SO2 and see what happens. I'd hate to throw this PN away...the grapes came from Francis Mahoney's Las Brisas vineyard.

 

[RPh_Guy]

Personally I wouldn't shell out that much for testing acetaldehyde. (And by the way, acetaldehyde isn't just produced by bacteria).

For the bitterness issue, maybe you could try some PVPP to help remove oxidized polyphenols, in case that's the issue. Just a thought.

 

[noofie2]

Thanks for your suggestion. I was not aware of PVPP. However I just looked it up on the web and found...
" PVPP is not commonly used in red wines, however, it can reduce bitterness and brighten the colour. In many cases PVPP can also reduce certain off-flavours and bitterness."
I will give it a try.

 

[noofie2]

I will be picking up some PVPP today. In the meantime I re-tested the wine last night and it was still bitter. I added 1/8tsp of Xylitol sweetener into the 120ml sample and it tasted much better....no bitterness but also not yet sweet. It even brought out more fruitiness. Rph Guy ... does this make sense? Have you used this to get rid of bitterness?

 

[RPh_Guy]

No but if it works then it works!