Re-application of sorbate?

[MrFrench]

I have 1gallon of a country wine in a demijohn. It had fermented dry so at the end of January it was sulphited, racked, degassed and sorbated with 1/2 tsp.

After this the wine would be stored for a couple of months before tasting and back-sweetening if needed.

So, a few days after adding sorbate i topped it off with a similar wine to get rid of the headspace. It was only about 50ml of wine added, but this was from a just-finished wine which had not been sulphited or sorbated yet. I’m worried I might have introduced live yeast again.

Will it need to be sorbated again? Or will the sorbate added a few days before be sufficient to stop any new population from establishing when backsweetening?

Thankyou!

 

[mainshipfred]

You should be fine. A lot of people back sweeten immediately after adding the sorbate.

 

[winemaker81]

Also, overdosing sorbate can produce off flavors, so you want to follow package directions and add it only once.

There is no need to add sorbate until just before you backsweeten. And if not backsweetening, don't add it.

 

[MrFrench]

Thank-you both, appreciate the advise and reassurance. It sounds like it should be fine to backsweeten so I’ll crack on with that and watch for re-fermentation.

 

[BigDaveK]

I'm just thinking out loud because I don't know the answer....

Will the sorbate be effective at preventing renewed fermentation with back sweetening occurring months later since the sorbate itself breaks down and oxidizes over time?

 

[winemaker81]

I'm just thinking out loud because I don't know the answer....

Will the sorbate be effective at preventing renewed fermentation with back sweetening occurring months later since the sorbate itself breaks down and oxidizes over time?

There may be a time limit on the sorbate, but it's at least months. There's also the fact that I've had 7 yo backsweetened wines not restart in the bottle, so I don't believe that any time limit on sorbate in the wine is a practical concern.

That said, I typically add sorbate, backsweeten, and bottle in one session, so I have not tested this hypothesis.

 

[Raptor99]

Will the sorbate be effective at preventing renewed fermentation with back sweetening occurring months later since the sorbate itself breaks down and oxidizes over time?

If oxidation is the cause of sorbate breaking down, then if we limit oxygen exposure and add Kmeta we should be good. We want to limit oxygen exposure for many reasons.

 

[BigDaveK]

@winemaker81 and @Raptor99 - I know, I know...and I agree in an essentially closed system with the addition of kmeta that oxidation shouldn't be a problem. But this a unique situation since the sorbate and back sweetening will be months apart. In addition to oxidation, some molds and lactic acid bacteria actually metabolize sorbate. So, like I said, thinking out loud, will there be the minimum amount of sorbate needed months later when sugar is finally added? Probably, but who knows for sure?

FWIW, it was a surprise to learn that sorbate can oxidize and also be used as food by some organisms. Who knew?

 

[winemaker81]

@BigDaveK, sugar has nothing to do with the situation. Sorbate doesn't interact with the sugar -- it works in conjunction with K-meta to keep yeast from reproducing, and I have demonstrated this effect is good for 10 years (consumed last bottle of lightly backsweetened metheglin at the 10 year mark).

If there's no new sugar for the yeast to eat the sorbate is unnecessary, but we're discussing sorbate breaking down and possibly no longer being effective. I don't know of any evidence of this being a real problem.

This is a good discussion, but I'm just as happy that there's no issue to address.

 

[BigDaveK]

@BigDaveK, sugar has nothing to do with the situation. Sorbate doesn't interact with the sugar -- it works in conjunction with K-meta to keep yeast from reproducing, and I have demonstrated this effect is good for 10 years (consumed last bottle of lightly backsweetened metheglin at the 10 year mark).

If there's no new sugar for the yeast to eat the sorbate is unnecessary, but we're discussing sorbate breaking down and possibly no longer being effective. I don't know of any evidence of this being a real problem.

This is a good discussion, but I'm just as happy that there's no issue to address.

This is fun! And I agree there's no real issue.

My point was what if the sorbate degrades before the addition of sugar? Would it still be effective?

And sugar DOES have something to do with the situation. Sucrose protects sorbate from degradation and we add them at the same time. But in this instance there will be months in between hence my curiosity.

https://www.researchgate.net/public...effect_on_microbiological_and_sensory_stabili

 

[Rice_Guy]

* wine is a ReDox soup. We have many chemicals which can oxidize producing old tasting / brown pigmented wine. ReDox happen as a cascade, the most reactive being consumed first.
Q: what is the ReDox state? ,,, As a young wine it probably has a lot of chemicals capable of soaking up electrons.
* I operate with a logic that yeast can starve or otherwise die a natural death. (David I haven’t seen data on yeast.) As an example E. coli is an indicator of fecal contamination within the last three weeks/ ie how long it would live in water without reproducing.
Q: how long from when the log phase/ active growth was happening? A year? I wouldn’t worry.
* pH? The higher the pH the more sorbate in the salt form, ,, low pH will encourage acid form. Acid form should esterify and form ethyl sorbate / bubble gum flavor.
You probably are at least 3.5 pH.
*
—— grandkids just came over oops

 

[winemaker81]

My point was what if the sorbate degrades before the addition of sugar? Would it still be effective?

Given that yeast survives for typically 12+ months, it's obvious that sorbate is still effective up to the time the yeast finally dies off, so the problem does not exist.