Adjusting "finished" wine--Lab results

[johnc3]

With apologies for any ignorance shown, I grow Zinfandel in a hobby vineyard near Calistoga. I have about 18 gallons of 2015 in glass now, and was close to bottling it.

I sent a sample to a local wine lab but have no idea how to interpret the results in terms of what if anything to do with the wine before bottling. They are:
Alcohol--14.62%
PH 3.35
TA 7.5g/L
Acetic acid (oops) 0.3 g/L (320mg)
Malic acid 0.25g/L
Free and total SO2--not detected
Residual sugar .48g/L

My questions are: should I add sulfur to the wine? Seems like this would be a good idea but how much and how? Camden tablets?

Are these ranges "acceptable?" Yes, taste is critical but I'm wondering whether, for example, the malic acid level is too low or whether the wine should be tossed for the acetic acid in it.

Any insights or links to the right place to read about these issues very much appreciated. Thanks!

 

[Johnd]

With apologies for any ignorance shown, I grow Zinfandel in a hobby vineyard near Calistoga. I have about 18 gallons of 2015 in glass now, and was close to bottling it.

I sent a sample to a local wine lab but have no idea how to interpret the results in terms of what if anything to do with the wine before bottling. They are:
Alcohol--14.62%
PH 3.35
TA 7.5g/L
Acetic acid (oops) 0.3 g/L (320mg)
Malic acid 0.25g/L
Free and total SO2--not detected
Residual sugar .48g/L

My questions are: should I add sulfur to the wine? Seems like this would be a good idea but how much and how? Camden tablets?

Are these ranges "acceptable?" Yes, taste is critical but I'm wondering whether, for example, the malic acid level is too low or whether the wine should be tossed for the acetic acid in it.

Any insights or links to the right place to read about these issues very much appreciated. Thanks!

The detectable levels for VA are 600-900 mg/l, you're under that, but if you've got the bugs in there, get some sulfite in there quick!!

We're it me, I'd use powdered KMS, 1/4 tsp per 6 gallons, shut those suckers down. You won't be able to do MLF to get your malic down, but your other numbers look ok.

Check this out from UC Davis. http://waterhouse.ucdavis.edu/whats-in-wine/volatile-acidity

 

[whippetgood]

To me the pH looks a bit low. And the ta a bit high, but taste will tell you more. You have some malic acid in there which seems to say no secondary (MLF) fermentation has taken place. The acetic is a potential problem but keeping things clean and more importantly, air off of the wine. Acetic thrives in oxygen.

Correcting the pH can be done by adding some pot carbonate to precipitate out some acid. The other thing you could do is put it through MLF, that will raise your pH a bit as well. But the problem with doing that is that your wine isn't completely dry. So if you run MLF, once the malic acid is converted the mlb will then start eating the remaining sugar, with the byproduct then being va.

So if it were me I would try to restart fermentation, get the wine dry, put it through MLF, and then get so2 on it to keep it as clean as possible. The lower the pH the more stable your wine will be and the less so2 you will need. Try to keep so2 to the least you can get away with. Because every time you add so2 your color and nose will take a hit, which over time will add up.

If you taste it and it seems like the acid is too high then I usually wait until I'm ready to bottle before raising pH. That way you get the benefits of the acid giving you stability, and more effective so2 management .

 

[Scooter68]

I wouldn't worry about the pH at all It's within tolerable range. I've seen commercially bottled wine of winery web sites with pH readings on the bottle of 3.18. It depends on the variety of wine.

The residual sugar is fine you have an "Off Dry" wine.

Quote from Winemakermag.org:

"Residual sugar concentration is a measure of the amount of sugar solids in a given volume of wine following the end of fermentation and any sugar addition when making a sweet wine. Residual sugar concentration is expressed in grams per liter (g/L) or as a percentage of weight to volume. For example, a wine with 0.2% residual sugar contains two grams of sugar in a liter of wine, or approximately 1/4 ounce in a gallon. Dry wines are typically in the 0.2–0.3 percent range, off-dry wines in the 1.0–5.0 percent range, and sweet dessert wines in the 5.0–15 percent range."

Acid varieties present looks a bit odd - The Acedic acid is the concern - that's the vinegar acid. Couldn't find you any solid reference points but the biggest question is - Have you tasted the wine? That's the key.

S02 Can be fixed with a campden tablet/K-meta. You don't want to over-do it though Campden tablets 1/gal K-Meta I believe is 1/4 tsp per 5 gallons (Best to ready instructions on the container for K-Meta)

Didn't see any mention of Tartaric acid and that seems a little odd. Normally that's what gives the tartness to the wine so again - taste test needed. If you are getting a vinegar taste it may be "game over" as removal of it is about impossible - BUT let's see what the senior members say about it. With that size batch you don't want to rush to a decision - The safest step to do right away is the K-Meta/Campden tablet addition - The SO2 is what, along with Alcohol, preserves your wine. Address that ASAP.

Alcohol by the way is fine - upper end for some folks but not an issue.

PS I pm'd a senior member and mentioned you needed help - hopefully you get someone to give you some counsel on the solution. Don't be afraid to let your taste test guide you. If the wine is for you and you like it... that's what matters.

 

[stickman]

The lab numbers give you something to consider while tasting the wine.

As others have said, the PH looks a bit low, but you need to taste and confirm an acceptable level of tartness, and only adjust if needed.

The acetic acid is fine, in fact it is in the normal range, it is difficult to make a wine with less than .3g/l acetic acid.

The sugar fermentation is complete.

I think Whipp has it right, the ML fermentation is not complete, but at this stage it would be difficult, not impossible, to restart and get it completed. Your % alcohol is fairly high which may be responsible for why the ML fermentation stopped.


If you are thinking of bottling, I would taste and correct for tartness if needed, and add the appropriate sulfite dose depending on the final PH. If you have not added any sulfite yet, with 18 gallons at the current PH, you need about 6g of Kmeta and this assumes some of that dose will bind immediately. I would then filter before going to bottle to ensure stability; .2 micron nominal (not absolute) is adequate.