Potential Stuck Fermentation Prior to MLF

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Good morning everyone,

This is my first post on this forum, hoping to get some great pointers from you guys. I have some questions that I don’t know the answer to (don’t let me fool you, I’m still a beginning that just does a lot of research haha)

Last weekend, I crushed 7 cases of Pinot noir (must Was about 28-30 gallons). I measured an OG of 1.080, so I added about 5 lbs sugar to get to 1.100. I also measured pH at 3.75, so I added about 200g of tartaric acid to get it down to about 3.5. K Meta was added at a rate of 1/4 teaspoon per ~6 gal (1.25 tsp total), and pectic enzyme (don’t remember the dosage but maybe 10 tsps since instructions said 1 tsp per gal but I didn’t have enough).

I waited about 6 hours before pitching yeast. Added Lalvin RC212 to warm water and waited for activity prior to adding to must. Fermentation was going along great for 4-5 days, and seemed to hit a brick wall at a SG of about 1.000 or 1.005. I pressed grapes into secondary fermenter to prevent oxygen exposure since fermentation isn’t active anymore. It has been steady at this level for a few days now. No visible activity in carboy. Granted, it is possible that the fermentation is done, though I am used to seeing it below 1.000.

My question is: I am planning on putting this wine through malolactic fermentation, and I’m reading that residual sugar can lead to production of VA (which I believe is “volatile acidity”), but nobody says how much is too much. Should I be worrying at this level of residual sugar? If so, I can try and pitch a yeast like EC1118 with a higher alcohol tolerance to try and power through the end.

Any thoughts? Thanks!
 

crushday

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Hey, first of all, welcome to the site. From your post, you definitely have some experience. Again, welcome.

As far as a stuck fermentation, what nutrients did you use and at what frequency? And, is your gravity 1.005 or 1.000? A starting gravity of 1.100 means you‘re not hitting your head on the yeasts tolerance ceiling. Maybe give the must a stout stir. My experience is that it could take up to a 5-7 days for the yeast to come out of shock from pressing. At the right temperature, with enough nutrients and residual sugar they should finish up the job. Time is likely your best friend.

Many people co-inoculate bacteria before AF is completed. So, you shouldn’t have any difficulty or concern pitching the bacteria in an environment containing residual sugar.
 
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@crushday @sour_grapes

just looked more closely, and I believe the reading is 1.000 even. The liquid peak is at 0.998 but the overall liquid level is closer to 1.000.

I did not add any yeast nutrients. My understanding is this is not always required, and should only be used as necessary to make sure you don’t end up with excess nutrients after fermentation.

I also put the hydrometer in sink water and saw 1.002. Therefore, looks like my reading is likely below 1.000 after all. Safe to say my fermentation is done (or good enough), and I can throw in the ML Bacteria. Should I rack off gross lees prior to inoculation? Also, pH is around 3.7 post AF. Is this too high going into MLF?
 
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crushday

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From your description, the hydrometer might be off - but only make that determination based on the temperature range of your appliance. In other words, you might need make a number adjustment based on water/must temperature.

Also, someone else will need to answer your pH question and the effect on MLF. But, here is a helpful resource at MoreWinemaking: https://morewinemaking.com/web_files/intranet.morebeer.com/files/mlf09.pdf

Onward…
 
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Reluctant Chemist

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From your description, the hydrometer might be off - but only make that determination based on the temperature range of your appliance. In other words, you might need make a number adjustment based on water/must temperature.

Also, someone else will need to answer your pH question and the effect on MLF. But, here is a helpful resource at MoreWinemaking: https://morewinemaking.com/web_files/intranet.morebeer.com/files/mlf09.pdf

Onward…

Hi,
I'd consider lowering the pH a bit before MLF. At 3.7 and above chances increase for developing off flavors during MLF.
 

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