Adding Metabisulfite

Hey everyone just a quick question and this is my first time posting. Been reading and observing for a while now. I have been working on a apple mango wine for the wife. I may have messed up, not sure.

I started the primary fermentation off in a bucket, started with apple cider and mangos. I let it set exposed to air for about 24 hours before pitching the yeast and primary fermentation seemed to go well. After about 2 weeks in the primary fermenter the sg was 1.028 and held steady at that gravity for a few days. I added in potassium metabisulphate at this time. Then I racked it the next day and added Potassium Sorbate and Sparkolloid to the carboy that i racked into.

About 2 more weeks have now passed, while it was sitting I noticed that the fermentation was still going on. I did a test today and found the the SG was not at 1.012. I also tasted the sample it seems to taste alright to me.

Please correct me if I am wrong but the potassium metabisuplate should have killed any yeast that that was present in the wine when I added it. Since this isn't what happened is it safe for me to add more to the wine? I used 1.8 tbps when I originally added to the 6 Gal of wine in the carboy.

I'm not as worried about the clarity at this point, I know that can take some time to clear up. I'm more concerned what to do about the presence of fermentation that is still ongoing.

The metabisulphate will sterilize the yeast and keep them from replicating, but NOTHING will chemically stop an active fermentation. You need to ferment out completely, then treat with chemicals, then back-sweeten to taste.

Wine yeast has been refined over the centuries to be very tolerant of metabisulfite, thats why we can still ferment after adding it. The metabisulfite stuns other yeasts and things so that the good yeasts can take over.

The correct amount of sulfite and sorbate will work well enough to allow some sugar to be added, but not really good enough to "stop" an active ferment.

Thanks for the info.

leader716 said:

Then I racked it the next day and added Potassium Sorbate and Sparkolloid to the carboy that i racked into.

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If you added Potassium Sorbate, then that should have stopped fermentation within 48 hrs (provided you added enough). What is your gravity reading today? If it has continued to drop, then you didn't add enough or the additive is old.

I added the Potassium Sorbate on the 9th of March, fermentation didn't stop until over the weekend, where it finally settled to the 1.012, which it is at the same gravity at this time. Right now I am just waiting on everything to clear but I am curious why adding the Potassium Sorbate didn't halt the fermentation. I can look tomorrow on how much i put in the wine as I don't have the numbers in front of me at this time.

I recently purchased the Potassium Sorbate from my local brew shop, but I have no idea how long it was sitting here before I purchased.

LKABrewer is spot on, Potassium Sorbate will stop any new fermentations, it will not stop an active fermentation, this is a big misconception.
Once it has fermented to dry, you stabilize with meta and sorbate to prevent any new fermentations from starting up after adding the sweetener of your choice to back sweeten.

I have a related question, so figured I'd politely hijack this thread.

I have a 1 gallon batch of Loquat wine that I started in very late December, which is now at 0.996, crystal clear, and the water was sitting at neutral in the airlock. So in other words, the fermentation is done.

I don't backsweeten my wines, and prefer them dry. Do I need to stabilise this at all? I've normally just added K-meta, but at SG of less than 1, do I actually need to? I bottle in screwcap wine bottles, so usually just open the same bottle every few days for the first couple of weeks to make sure it doesn't have any built-up pressure.

Meta to stabilize is all that you will need.

pumpkinman2012 said:

Meta to stabilize is all that you will need.

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And you don't even "need" that to stabilize, but it is a very good idea since it works as an antioxidant as well as an antimicrobial so that the wine will last. If you're going to drink it in the next three months, I might not even use the k-meta but since I tend to age wines I always use it.

Yooper, I agree, and to be honest, I always test my SO2 levels with the Vinmetrica SC-300 to see if I actually need to add any meta and if so, how much.