How quick does frozen yeast become active?

[Calder]

Several years ago I froze some yeast using a glycerin solution. I used recommended procedures and dilutions I read in a number of places. I think my method of freezing was OK.

Yesterday was the first time I have tried to re-activate some of the frozen yeast. I used two vials (to double the chance of it working), the vials were dated 2011. I placed the vials in warm (not hot) water to thaw quickly. Poured off the glycerin solution and added to about 6 ozs of 1.020 wort.

It is now 24 hours on, and it looks like there is a reasonable amount of yeast at the bottom of the container, and fermentation may be complete. Is it possible the yeast could have worked that quickly? I was expecting it to take a few days.

Yeast has been in an insulated bag with some some cold packs in a chest freezer the whole time.

There was a fair amount of yeast in each vial, so I could just be seeing the original yeast, but it does look like there is more than I started with.

 

[doomy86]

Probably not, i would wait another 2 days and then step up.

I harvested alot of yeast from bottles and it always took them 2 - 5 days to ferment out the first step.

A clear sign of fermentation are bubbles sticking to the side of the vial. Of course this could also be something else than your yeast. But you will find out soon enough.

 

[Calder]

Two days were not enough. I put it in the fridge for a coupe of days, decanted the wort and measured gravity. Still at 1.018.

Now it is back in a new starter to see if it goes ..... or is dead. Currently at 24 hours and nothing.

 

[kh54s10]

The couple of year + old samples I did were 5 ml yeast, 5 ml glycerin and 10 ml water. I thawed overnight in the refrigerator, left the vial on the counter for a couple of hours then added to a 250 ml starter of 1.025 wort for 2 days on a stirplate. I then did an addition of .5 liter 1.035 wort for another 2 days. Chilled and decanted for a last addition of 1.5 liters at 1.040 for another 24 hours. I had what looked like a normal layer of yeast/trub at the end and the beer started fermenting in 4-6 hours.

 

[Calder]

It's Alive!

6 years in chest freezer

2 days in 1.018 wort, cooled - no fermentation (checked gravity of wort after 2 days in fridge).

Added to 1 pint 1.040 wort - 3 days and fermentation going.

...... Should have left it longer in the initial low gravity wort, but everything seems to be going OK now.

I have about a dozen different yeasts in the freezer. This is the first I've tried to use - good to know they are good.