Using old yeast

[KrazySquirrel]

Is there a length that one can keep yeast for after washing it?

I have a few varieties that I've harvested from the bottom of a carboy with sanitized (boiled) water in glass jars. I've kept these in my brew fridge.

Reason I ask is because I brewed a bohemian pils 4 days ago and have not had a fermentation yet. I made a 1600mL starter 4 days before brewing and split into 2 corney kegs for primary fermentation. This was my first time using a stir plate to make a starter so I couldn't really tell if there was more yeast after the starter was done than before. I also didn't crash the yeast out of suspension and think i may have dumped a bunch of it when I decanted the starter. I'm thinking that I either severely underpitched or the yeast was dead. Any ideas to avoid this problem in the future?

 

[highgravitybacon]

Is there a length that one can keep yeast for after washing it?

I have a few varieties that I've harvested from the bottom of a carboy with sanitized (boiled) water in glass jars. I've kept these in my brew fridge.

Reason I ask is because I brewed a bohemian pils 4 days ago and have not had a fermentation yet. I made a 1600mL starter 4 days before brewing and split into 2 corney kegs for primary fermentation. This was my first time using a stir plate to make a starter so I couldn't really tell if there was more yeast after the starter was done than before. I also didn't crash the yeast out of suspension and think i may have dumped a bunch of it when I decanted the starter. I'm thinking that I either severely underpitched or the yeast was dead. Any ideas to avoid this problem in the future?

Yes. Cold crash and be careful when decanting. Pitch a starter after 12-24 hours.

 

[WoodlandBrew]

I have a slurry from September that is still at about 50% viability and a low bacteria count, but I also have one from October that is near 10% viability with a high bacteria count. How long they last can vary quite a bit. Keep things as clean as possible and it should last a while.

 

[kh54s10]

I see a couple of problems. First is that even though you made a starter it was probably too small. If the pils is a lager you would have needed a lot more yeast. Second, if you decanted without letting the yeast settle, you poured out a large amount of the yeast. Maybe even more than you started with.

I have heard of people making successful starters from harvested yeast that was over a year old. I would assume it required several steps for the starter.

I freeze yeast and have used 5ml samples successfully that were stored for more than 6 months.

 

[WoodlandBrew]

Agreed, the OP has likely under pitched and is seeing some significant lag. A 1.6 litter starter from a slurry could produce any where from 100 billion to 300 billion cells. Then pouring out the liquid without crashing could have lost another 25%. It seems very low for 10 gallons of beer.

 

[KrazySquirrel]

Thanks for the responses. I pitched a smack pack into each fermenter two days ago and now there is a good fermentation.

How long is harvested yeast viable for?

 

[WoodlandBrew]

Thanks for the responses. I pitched a smack pack into each fermenter two days ago and now there is a good fermentation.

How long is harvested yeast viable for?

Months, but it's hard to put a real number on it because viabily can change quite a bit depending on conditions.

 

[hiphops]

I've brewed with yeast that's well over a year old (like 15 months.) I always use a starter and, frankly, they come out good. In fact, I'm using a 1056 that has been in the fridge since august 2011 in an ipa with an OG of 1.065 and is now down below 1.010. I never understood why (other than wanting to make a sale) eveyone says you gotta use "fresh" yeast, whatever that means. Yeast is an incredibly adaptable and tough organism: its tougher than humans.