Stabilizing - Sorbate / Kmeta.. both?!?

[bein_bein]

I have noticed in recipes here, that at the end of fermentation a lot of them say to add kmeta AND sorbate. In talking with my local supplier, I was told that is overkill, and you only need to use one or the other. what is the consensus??

On a different/related note....I think my concord/grape blend wine has undergone self-induced MLF since bottling a year ago. I have reopened all the bottles and they have been back in the carboy for a month, but I am still getting little tiny bubbles. SG is at .998 I degassed it vigorously with a vacuum racking x 2, but still see some bubbles...so my questions are..:
1. How can I tell for sure if this is MLF
2. Is there a way to stop MLF once it is started?
3. How long can MLF take, and how do I know when it's done??

Thanks guys!
BB

 

[Thig]

I think he is wrong on your first question. Kmeta is to keep the wine from spoiling and Sorbate is to keep the wine from refermenting if you add more sugar later. They do not accomplish the same purpose. If you are not going to backsweeten then you do not need Sorbate.

I will await some answers on your MLF question because I want to know the same thing.

 

[Rocky]

BB, I think I would get a different "local supplier."

The two serve different purposes. Potassium Metabisulfite is used to protect the wine from spoilage by bacteria. Potassium Sorbate is added to wine to prevent re-fermentation after the wine has been stabilized and sweetened. Using K-sorbate can be overkill if your wine is fermented to dry and you do not intend to back-sweeten it. Some people believe that using K-meta is not required and prefer the "old fashioned" way of making wine, i.e. as was practices long ago before people knew why wine "spoiled." My personal opinion on the latter is that such practice, while possible, is risky so I do not take the risk.

Sorry, I can't help om the MLF question but I am sure someone will.

 

[BobF]

As others have said, you need sorbate to prevent referment when there is residual sugar.

When you add sorbate it is very important to keep the sulfite levels maintained. The sulfite inhibits LAB (the bacteria that performs MLF), which will otherwise metabolize the sorbate and cause irreversible damage to the wine - geranium! This is the reason you add both when adding sorbate.

If you're not using sulfites, then you shouldn't use sorbate.

 

[bein_bein]

That's kinda what I thought about the k-meta....Fortunately the person i got the info from wasn't the owner whom I trust as he is very knowledgeable....i'lll just have to make sure I talk to him from now on and not his college-aged help....

So as I'm reading Bobf's reply am I right in thinking that since I always use a campden tab (k-meta) when racking , that is enough to keep sulfite levels maintained? Should I be adding a tab at every racking (typically 6gal batches) ?? I have been trying to reduce the use of campden tabs to keep sulfite levels low.... Man...just when ya think you have a good handle on this stuff it gets all complicated and confusing again!!! lol

So any input on why this batch keeps a bubblin'??

 

[BobF]

Without measuring it's not possible say you have enough kmeta with certainty. How often do you rack? How much air exposure does your wine get when you rack? How often do you remove the airlock to get a taste or a smell? Not really looking for specific answers, the point is that these vary winemaker to winemaker. And every wine is different.

In general, if you are adding a full 1 tab per gallon dose at every racking, you *probably* have plenty. Maybe more than you need. If you've added kmeta two or more times and the last addition was less than a month ago, you *probably* don't need to add more with the sorbate.

Testing is the way to go, but it is expensive - too expensive for not very many batches a year, IMO.

Sorry I can't give you firm answers.

If the bubbles are really tiny and form a thin ring at the wine surface, you *probably* have an MLF going. MLF bubbles are noticeably smaller than yeast bubbles and there are a lot fewer of them. Monitoring malic levels via chromatography is the only certain way I know of to identify whether or not you're seeing MLF action.

If you previously sorbated this wine and MLF runs, you will eventually be able to tell by smell and taste. It's not pleasant. I've had it happen to batch I got loose with, ignoring sulfite levels for too long.

 

[mmadmikes1]

Sorbate alone is a waste of time, you will need to add K meta also. Sorbate prevent yeast from reproducing but does nothing to get rid or stop the living one you have there from fermemting the sugars. Good guess is that it is not MLF but re-fermenting. Check SG and I will bet is is lower than when you bottled. . I do not use sorbate at all any more and haven't for several years. I use time. Haven't had any bottles go bad either. Still use K meta on white wine to prevent oxidation but alcohol is what I use to prevent spoilage

 

[bein_bein]

blah blah blah....

In general, if you are adding a full 1 tab per gallon dose at every racking, you *probably* have plenty. Maybe more than you need. If you've added kmeta two or more times and the last addition was less than a month ago, you *probably* don't need to add more with the sorbate.
....blah blah..more stuff that was said...

1 campden tab per gal?? I have always added by 1tab/6gal ratio at each racking, typically 3 rackings over the course 8-12months. Not to question your process (he said as he did so... ) Is this the ratio that most people use campden tabs?? thanks...

 

[BobF]

blah blah blah ...

Yes, 1 campden tablet per gallon is the standard dose ...

blah blah blah ...

Just a guess, but with 3 total tabs in a 6g batch over an 8-12month period, I'd say you have zero free SO2 protecting your wine.

blah blah blah ...

 

[BobF]

BTW, my process is to use kmeta powder and to calculate/measure dosage

 

[Tom_S]

I remember reading somewhere, but unfortunately can't find it now, that you should always use metabisulfite when you use potassium sorbate, or else you run the risk of causing bad odors & flavors in your wine. I think it has something to do with the sorbate stressing the yeast but not killing it. Probably along the lines of what madmikes1 said above. At any rate, you need the metabisulfite to keep oxygen out of the wine to prevent oxidation or spoilage by bacteria anyway.