Storing yeast under distilled water?

[SacoDeToro]

While you can store yeast for extended periods of time with the proper equipment, for most brewers it's usually best to repitch things ASAP. It's always nice to when you're able to throw a fat pitch of healthy yeast into your next batch. When I pull yeast from the bottom of a conical, I usually leave 2-3" of finished beer on top (I usually collect into a glass growler). Not only does this help create a barrier, but there are still some minute amounts of sugars available and the yeasts' glycogen levels don't drop off quite a quickly. I'll tell ya, nothing fires off like yeast that was harvested less than 24 hours before. I've had lag times of as little as 15 minutes from repitches of WLP530.

[Guido]

While you can store yeast for extended periods of time with the proper equipment, for most brewers it's usually best to repitch things ASAP. It's always nice to when you're able to throw a fat pitch of healthy yeast into your next batch. When I pull yeast from the bottom of a conical, I usually leave 2-3" of finished beer on top (I usually collect into a glass growler). Not only does this help create a barrier, but there are still some minute amounts of sugars available and the yeasts' glycogen levels don't drop off quite a quickly. I'll tell ya, nothing fires off like yeast that was harvested less than 24 hours before. I've had lag times of as little as 15 minutes from repitches of WLP530.

I'm envious that you can brew with a fast turn around time between batches. My schedule is very erratic, and sometimes I go for a month between brewing sessions. I'm leery about keeping the yeast more than two weeks under spent wort. It's frustrating to have plenty of grain and hops and then have to make a special order for yeast. I figure if I can just extend the yeast storage time for another two weeks by using distilled water, I'd would be good to go.

[Quin]

Exactly, if anything were to happen, water would go from the lower concentration of particles environment in the distilled water to the higher concentration of particles environment in the yeast in an attempt to equalize the concentrations. This is what happens with red blood cells in distilled water. They swell and burst. That's why various medical testing uses 9% saline, which is isotonic--equal concentration. For some reason, this does not affect the yeast. Perhaps being a plant vs animal cell makes the difference, but I don't know why.

That's osmosis, right?

I am referring to diffusion - moving from a higher concentration (yeast cell) to lower concentration (distilled water) across a semi-permeable membrane (assuming the cell wall is permeable to the mineral/nutrients).

[Guido]

Exactly, if anything were to happen, water would go from the lower concentration of particles environment in the distilled water to the higher concentration of particles environment in the yeast in an attempt to equalize the concentrations. This is what happens with red blood cells in distilled water. They swell and burst. That's why various medical testing uses 9% saline, which is isotonic--equal concentration. For some reason, this does not affect the yeast. Perhaps being a plant vs animal cell makes the difference, but I don't know why.

That's osmosis, right?

I am referring to diffusion - moving from a higher concentration (yeast cell) to lower concentration (distilled water) across a semi-permeable membrane (assuming the cell wall is permeable to the mineral/nutrients).

Right, it's osmosis and it will diffuse across a permeable membrane from a high water/low particle concentration (hypotonic)--the DI water-- to a low water/high particle concentration (hypertonic)--the cell-- in an attempt to equalize the concentration acosss the membrane. This is why nothing can live in stuff like jelly and syrup. It' so concentrated (hypertonic) that it sucks all the water out of the bacteria (hypotonic), etc...

[ApresSkiBrewer]

Some might shake a finger at me, but I have kept yeast slurry from my primary in an eurlanmyer flask, in the fridge, for up to 4 weeks. I always make a starter to test for viability with yeast I'm repitching older than 13-14 days... but I've gotten lucky so far with no infections/funkyness from this method. I'm going onto my 5th generation of WLP013 and the forth gen made a nice clean brown. Its the lazy way, and it works for me.

[Quin]

Right, it's osmosis and it will diffuse across a permeable membrane from a high water/low particle concentration (hypotonic)--the DI water-- to a low water/high particle concentration (hypertonic)--the cell-- in an attempt to equalize the concentration acosss the membrane. This is why nothing can live in stuff like jelly and syrup. It' so concentrated (hypertonic) that it sucks all the water out of the bacteria (hypotonic), etc...

OK. I see this is going nowhere. Just use distilled water.

[boobookittyfuk]

Exactly, if anything were to happen, water would go from the lower concentration of particles environment in the distilled water to the higher concentration of particles environment in the yeast in an attempt to equalize the concentrations. This is what happens with red blood cells in distilled water. They swell and burst. That's why various medical testing uses 9% saline, which is isotonic--equal concentration. For some reason, this does not affect the yeast. Perhaps being a plant vs animal cell makes the difference, but I don't know why.

it doesn't affect yeast because they have a cell wall. Other cells that have a lipid membrane burst.

[Nyakavt]

While you can store yeast for extended periods of time with the proper equipment, for most brewers it's usually best to repitch things ASAP. It's always nice to when you're able to throw a fat pitch of healthy yeast into your next batch. When I pull yeast from the bottom of a conical, I usually leave 2-3" of finished beer on top (I usually collect into a glass growler). Not only does this help create a barrier, but there are still some minute amounts of sugars available and the yeasts' glycogen levels don't drop off quite a quickly. I'll tell ya, nothing fires off like yeast that was harvested less than 24 hours before. I've had lag times of as little as 15 minutes from repitches of WLP530.

I'm envious that you can brew with a fast turn around time between batches. My schedule is very erratic, and sometimes I go for a month between brewing sessions. I'm leery about keeping the yeast more than two weeks under spent wort. It's frustrating to have plenty of grain and hops and then have to make a special order for yeast. I figure if I can just extend the yeast storage time for another two weeks by using distilled water, I'd would be good to go.

If you make a starter you'll be fine. I've had "rinsed" collections of yeast (dilute with boiled tap water 4:1) revive after 6 months in the fridge. It could go longer, just haven't tried it. Making a starter will solve any yeast health issues that anybody is worried about.

There is a concern about contamination when you get down to a very low viable yeast population, so it's really best to do long term storage under sterile conditions, like with a sterile slant. For a month, you'll be fine in the fridge under beer diluted with water.