Malolactic bacteria and high SO2 levels?

[Marcool]

Hello all at winemakingtalk.com!

I am a newcomer to the forum, as I am too to winemaking.
Located in Nova Scotia, Canada, I purchased approx. 200kg of Marechal Foch red grapes two weeks ago. Stemmed and crushed they amounted to 175 L of must.
Here I went wrong for the first time : after de-stemming and crushing (which took lots of hands and a LONG days work) I was a little sloppy in adding K meta to the must. I wanted SO2 to be around 70 ppm (as I had some rot on the grapes), which - if my math is correct - works out to around 70 x 175 x 0.0017 = 20 g or 4 teaspoons. But my teaspoon-fulls may have been a little high, so I am guessing that amounted to more like 30g of K meta or 100 ppm of SO2...
The must tested in at 20 Brix, 11.5 g/L TA, and ph 3.2 (I know, terrible for wine making, but not so bad for our poor little northern Novascotian peninsula!)
I then cold soaked for about 24 hours, and inoculated with EC-1118, added sugar to raise sugar levels to 23.5 Brix (to reach 13.5% v/v alcohol), and the must rapidly fermented to dryness in just over 5 days. I pressed into carboys, and tests now show a TA of 8.5 g/L and ph 3.6.
Now to lower the acidity (which is still quite bracing) I wanted to put the wine through MLF, and then when winter sets in (and MLF is over) put it through a little bit of cold stab to precipitate some of the tartric... but my previous mistake has caught up with me : free SO2 levels are testing somewhere in the 40-50 ppm range (Chemetrics "Titrates" are anything but accurate... especially on reds!) and my research seems to show that at those levels MLF will be almost totally, if not totally, inhibited... (see here for more info)
I know I could also reduce the acidity with calcium carbonate or any other deacidification technique, but I would like to avoid this if possible (I know, my very first mistake was that I should have lowered TA of the must before even inoculating... too late now!) and I would really like to get some of the green apple taste out as that is rather predominant right now.
Another issue on my mind is the high price of ML bacteria, which I have already purchased for something around 70$!! and which I really, really don't want to waist.

So I am appealing to the more experienced wine makers out there, what would you do here (other than not have made my two previous mistakes!) :
-Do you think that by spring, the SO2 will have bound up enough that I can inoculate with ML and get a decent MLF then? With comparable results in taste and acid reduction that I would have had with MLF being performed right now?
-Or will the SO2 never fall below ML-inhibiting levels and should I just forget about ever getting rid of my malic acid?
-If so then is there a more elegant - and less chalk tasting - way of reducing my TA (I read that using CaCl to drop TA more than 3 g/L would surely result in taste change, and I can quite believe it : the amount of chalk needed to reach 6g/L TA would be around 400g!)

Thanks in advance for any advice you have.
Regards,

Mark.

 

[robie]

I wouldn't worry about the TA until after MLF, unless the pH is too low for your MLB. For MLF to start, pH is more important than TA. After alcohol fermentation is completed, you use potassium carbonate, not calcium carbonate.

That free SO2 level is not terribly high that it won't fall quite a bit in a few months of bulk storage. You can either splash rack it or let it set for several months. I would choose to let it set. Even one normal racking can sometimes really lower SO2 levels, so watch it.

Since it has to set, get it off the lees when it is time, then keep it topped off and preferably under air lock.

There are MLB that can handle a little higher free SO2 levels, but you might be better off just waiting. Check it once a month. Use a good tester to check free SO2. Morewine carries a nice, $100 test kit (# mt140) that does a good job.

When trying to start MLF, make sure the ABV, pH, temperature, and SO2 levels are good for your particular MLB. Since the wine will be pretty clear by then, I would purchase a MLF nutrient to make sure it goes well. To get it started, keep the temp up at the higher end of the MLB's tolerance.

Also, while it is setting, watch it and make sure MLF doesn't start on its own, which is likely not a bad thing. If the wine gets very still, then you start seeing small fizzing going on, you wine is likely in MLF on its own. However, that won't likely happen until the SO2 levels fall a little.

Purchase a chromatography kit to test that MLB has started and to tell when it has ended. I would not try to guess these with that volume of nice wine. When MLF is ended, if the MLB are not killed, they can start munching on other things that can mess up your wine.

Good luck!!!

 

[joea132]

If you only added sulfites after crush and not after fermentation then your levels are almost certainly within malolactic bacteria levels. The pH is high enough to let them work as well. I've added around 90ppm to grapes with rot and had my Malo right after Alcoholic fermentation. Maybe some opti-Malo plus is a good idea too.

As for reducing acidity, consider maybe buying some low acid California grapes to blend in. A good supplier should be able to tell you if they are low acid. I used potassium bicarbonate once with only slight flavor loss and no chalky taste. Don't focus too heavily on the chemistry. You might be surprised how much acid a Malo can remove. I reduced one batch from 1.0 to around .8 TA. It all depends on how much malic acid is present.

Long story short, I'd toss the malo bugs in now.

 

[joea132]

As said before make sure your temperature is in the mid 60s F to mid 70s F range.

 

[Marcool]

Thanks a lot for your replies Joe and Robie!
After a little more research I have decided I am going to inoculate now, as the pH is within the MLB's tolerance level, and although SO2 is high it will not destroy them but rather slow down their progression.
I will keep an eye (and a taste-bud!) on it from now on and see what the progression is like, maybe end up adjusting the TA later then if it still has too much of a bight.
Again, thank you for your help, and happy wine making to all!
Regards,
Mark.

 

[grapeman]

These guys are right on here in their advice. Get it in there and let it rip. Those numbers aren't bad at all for Foch. Once the mlf is done, it will be rounder but it's sharpness is one reason I prefer Leon Millot over Foch (but that is just my opinion).

Time will also be your friend here. Be sure though that when you are happy it has mellowed enough to add another dose of sulfites to protect the wine from further bugs.

 

[Marcool]

Just inoculated with ML a few hours ago, SO2 is still around 30ppm (twice what the ML package calls for!) but after racking, and about a week setting it hasn't moved one bit so I think it's best to just throw them in there.
I wonder if I should try to keep the wine warm now, the temperature range for ML is supposed to be rather wide (13 to 22 C says the package) but I'm closer to the lower end than the higher right now (the cellar is around 17 to 18 most of the time, but the real cold weather isn't here yet and it may go down or up depending on the furnace...) My best method up until now for keeping temperature under control has been an electric blanket ;-) Works great!
You know grapeman, Foch was just the grapes that I found around here, if I had had a choice I would have gone with a nice Mourvèdre, or Shiraz maybe, (I'm from southern France...) but that'll have to be some other year, in another climate probably!
Anyhow, thanks a bundle for your good advice guys, happy wine making!
Regards
Mark