how long for yeast to die, if ever?

[crabjoe]

I was just wondering, since wine usually gets better with age.

Let's say you'r bulk aging a wine.. how long will it take for the yeast to go dormant then eventually just die on their own? Is 6 months, a year long enough, or will sorbate or some other way always be need to make sure a fermentation doesn't start back up again, if any back sweetening is done?

 

[cmason1957]

I was just wondering, since wine usually gets better with age.

Let's say you'r bulk aging a wine.. how long will it take for the yeast to go dormant then eventually just die on their own? Is 6 months, a year long enough, or will sorbate or some other way always be need to make sure a fermentation doesn't start back up again, if any back sweetening is done?

I don't belive you can ever count on every single last yeast cell being dead. I think they go dormant and if any sugar shows up in the environment, they will fire up and eat it. Removing the yeast (through sterile 0.45 micron absolute filtering) or birth control potassium sorbate (along with potassium metabisulphite) are the ways to ensure no refermenting. Oh and high enough alcohol level to truly kill the yeast off.

 

[1d10t]

As wine makers most of our methods involve sanitation and not sterilization. It is always possible to reintroduce an organism that will eat excess sugar at every stage.

 

[crabjoe]

I don't belive you can ever count on every subtle lady yeast being dead. I think they go dormant and if any sugar shows up in the environment, they will fire up and eat it. Removing the yeast (through sterile 0.45 micron absolute filtering) or birth control potassium sorbate (along with potassium metabisulphite) are the ways to ensure no refermenting. Oh and high enough alcohol level to truly kill the yeast off.

I guess I'm going to have to keep using sobate.. or upgrade to a 0.45 absolute filter..

 

[crabjoe]

As wine makers most of our methods involve sanitation and not sterilization. It is always possible to reintroduce an organism that will eat excess sugar at every stage.

Are you saying to use sterile filter or possibly pasteurization versus sorbet?

 

[1d10t]

Are you saying to use sterile filter or possibly pasteurization versus sorbet?

No. I'm pointing out that even IF all the yeast are dead in the original batch you can still reintroduce something later in the process. Even bottling. Life is tenacious and exists in some of the most inhospitable places on the planet. I'd imagine that sterile filtering isn't 100% but good enough most of the time if you are careful with everything else.

 

[Rice_Guy]

How long to die depends

Are you saying to use sterile filter or possibly pasteurization versus sorbet?

* if you produce dry wine, yeast will not grow! Yeast require sugar for metabolism therefore it will be stable. Your issues will be secondary bacterial infections as metabolizing alcohol to vinegar.
* cold will not kill yeast . We have many bread products which freeze live yeast which is thawed, proofed once and baked
* temperature will kill yeast, a few examples: 180F for 30 seconds, 140F for 40 minutes, 110F for a week. A good reference is the package temp description, at the high end yeast is stressed and will eventually die HOWEVER expect H2S if you provide marginal growth temperatures.
* nutrient deficiency will stress and eventually kill the yeast, don’t use fermax if you want to kill em.
* metabisulphite combined with other variables.
* what did you inoculate with, a ale yeast lasts to about 8%, a champagne 18% and an industrial grain alcohol yeast 22%. Look at the package descriptions.

Wine is what I call a multi variable preservative system. It is complicated since a 14% alcohol kills faster than a 10% alcohol.

 

[Rice_Guy]

how long will it take for the yeast to go dormant then eventually just die on their own? Is 6 months, a year long enough?

I have had problems with 6 month old wine, therefore I will always use sorbate even though I don’t like to.
Running winter basement temp, 65/67F I have probably had a rate of one out of twenty five carbonate after back sweetening. I consider this a fair risk.
My target at the latest is to reuse carboys at a year when harvesting new crop.

If I had higher storage temperatures I should have more safety factor. Again temperature kills yeast/microbes, the effect is additive. Alcohol is part of the kill, metabisulphite is part, an anaerobic environment is part, CO2 is part, running clarifies which pull nutrients out is part, osmotic pressure is part, and pH is part of the kill, , , , (example if I steam treat food less than pH 4.0 the rule was 45 min in a kettle- package in a peroxide pouch or can and treat that 10 min extra).

I don’t know any hard and fast rule since wine is variable, unless I run a lab pasteurizer or run the 0.45 micron filter already mentioned.