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Mark Willstatter
 
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Default MLF wanted, but too much SO2

(Brad B.) wrote in message . com>...
> Here's my situation: I have a small (about 10 gal.) batch of Merlot
> that has finished sugar fermentation and has been pressed and racked
> off the gross lees. There is still some lees in the bottom of the
> carboys. I inoculated with MLF culture (Chr. Hansen) and warmed up
> the wine to about 70 deg.F. So far, after about 4 days there is no
> activity and I suspect it is due to the SO2 I added at crush (about 50
> ppm). I initially added this amount due to some rot in the grapes I
> had, and completely forgot about the MLF I would need later.
>
> In any case, I checked free SO2 with a titret and I get about 35 ppm
> (which seems high following fermentation but I know those things
> aren't the most accurate). So, what should I do now? Did the high
> SO2 kill the ML culture or will they spring to life once the free SO2
> levels decrease to their liking? I am thinking about racking,
> stirring, and adding some ML food, but I am mostly curious about the
> effect this has on the culture and if I will need to add another
> culture later.
>
> Thanks in advance...


It would be very unusual for enough of your 50 ppm to remain after
primary fermentation to bother MLF. Also, titrets are well known to
overstate SO2 on the order of 30 ppm - so your test verifies that your
free SO2 is probably near zero. MLF likes having the lees around and
being anaerobic, prefers a high CO2 environment - neither of which
will be helped by racking. It also sometimes takes awhile to get
going - keep in mind that this is a process that can often take some
time to get started and weeks (or even a couple months) to complete.
Your temperature is fine and your MLF bacteria should have the
nutrients they need in what you have already. My advice at this point
would be to hang tight and be patient. Also, if you haven't done this
before, keep in mind that MLF activity is pretty subtle compared to
primary fermentation. When it's going strong, you can usually detect
tiny CO2 "comets" (assuming you're in glass), especially up at the
neck but it's usually not enough to make an airlock go wild. If you
don't see anything like that within a week or so, then maybe you can
start worrying! I hope that helps.

- Mark W.