Yeast longevity

[Obelix]

This is more for info....

I crush between 200 - 300 kg of grapes a year, and typically use 80gm.
To be cost effective I need to buy in a packet of 500gm.
My first batch was in 2018 - when I bought 500g. Used it again in 2019, then discarded it to be safe - Wasted 340gm.

So I bought a new packet of 500gm he yeast in 2020, used in 2020 and 2021. Decided not to make any wine in 2022, and used it again this year.
With all the appropriate protection, nutrients, etc,, goes like nuts. Of course I tested it first.
I am pretty amazed that it has lasted this long. May test it next year again One never knows

 

[Ohio Bob]

With so much yeast leftover maybe you can turn it into yeast nutrient? Boil, dry into a powder.

 

[CDrew]

I've used some 3 years in a row without a single issue. I keep it stored under vacuum and in the fridge. Let us know if 4 years works. I'm certain it will.

 

[Rice_Guy]

Yeast is a numbers game, by this I mean that if on first year one puts in ten million viable cells you won’t really see the difference on year five if the weight actually is nine million viable cells. ,,, a ten percent loss.
If you want to kill yeast you could apply 110F heat or anything higher, you could apply moisture which starts to rehydrate cells and then not provide sugar so that they starve when their glycogen is used up. What else, drying the yeast paste in the factory will kill a few percent and a blip in the process could kill 90%, Getting exotic you could apply a sanitizer or alcohol or high water activity (sugar syrup), radiation, UV light or even 10,000 psi pressure. , , , , basically dry refrigerated storage should give years of viable cell count BUT if they get wet or above 110 there is a major problem.

 

[BigDaveK]

My baker's yeast is 10-11 years old, stored in the freezer, still works great. I have a small jar (kept in the freezer) that gets refilled when necessary from a bigger vacuum sealed container (that always magically travels to the bottom of the freezer).

 

[Sailor323]

I have used yeast that is 15 or more years past its use by date. Stored in the freezer. Yu can always proof it before use, good idea anyway

 

[Obelix]

With so much yeast leftover maybe you can turn it into yeast nutrient? Boil, dry into a powder.

If I knew this i 2019, wouldn't have wasted it. Thanks.
Just wasted 200g of bakers yeast. I can imagine this yeast would be OK as a nutrient.

 

[Obelix]

Didn't know it could be frozen. I keep it in a fridge.
Thanks.
I am not getting notifications of the replies. Better check the settings...

 

[winemaker81]

Didn't know it could be frozen. I keep it in a fridge.

Some vendors recommend refrigeration, not freezing.