Is it possible to store rehydrated dry yeast?

Hi,

Yes, I know dry yeast is considered relatively cheap, but I am brewing 10 litre/2.5gallons batches and I'm tired of throwing away half packages of S-04/05.

Can you, somehow, keep the yeast?

I thought about rehydrating the whole package in a sterilized jar, using half of it and then storing in the fridge, but then read somewhere that after 15 minutes the yeast is starting to starve and suffer.

It will depend on how long you are storing the yeast but I open a package, dump out about half to be rehydrated, fold the package top a couple time and hold it closed with a clothes pin. It will be fine in the refrigerator for a few days/weeks. Think of buying a jar of dry bread yeast. You open the jar, take out enough to make your 2 loaves of bread, put the lid back on the jar and back in the refrigerator until you make the next batch of bread. It lasts for months that way.

After dry yeast is rehydrated it is effectively the same as the liquid yeast you purchase. You would handle it the same as you would for storing liquid yeast.

If so, why is it recommended to pitch the yeast in 15 minutes after it has come to the wort temperature?

I'm afraid of just folding the package on itself, since it is not sealed and there is the risk of contamination.

Tamir said:

If so, why is it recommended to pitch the yeast in 15 minutes after it has come to the wort temperature?

I'm afraid of just folding the package on itself, since it is not sealed and there is the risk of contamination.

Click to expand...

Because after about 15 min the yeast runs out of its stored nutrients and begins to starve. If left this way it will begin to go dormant but some cells will die. It's not a good state to leave the yeast in. Liquid yeast is prepared for packaging differently but still loses viability rather quickly (several months).

Tamir said:

If so, why is it recommended to pitch the yeast in 15 minutes after it has come to the wort temperature?

I'm afraid of just folding the package on itself, since it is not sealed and there is the risk of contamination.

Click to expand...

That is so it is pitched at 100% (or close to) viability. Stored liquid or rehydrated dry yeast will be pitched after making a starter if the estimated viable cell count is to low for the beer planned.

I think, with appropriate sanitary procedures, there is less risk saving the dry yeast by taping the sachet closed.