For me, so far, looks like the answer is at least 22 months. Just successfully grew up a starter of 1450 that was slanted back in Oct '09. Looks and smells great.
It can last a really long time under the right conditions. Have you plated it? I have some of that strain that went petite on me, I’m going back to the stocks to see if it’s all of it or not. My frozen stocks are all bad, but the original stab I got it on is to be determined.
Okay Mr PhD (guess that should be Dr PhD), please educate me. I’ve never plated anything because I’ve never been inclined to grow up from a single colony. Are there other reasons for plating that might benefit my processes? Also, what does “gone petite” mean?
Petite mutants usually lack functioning mitochondria and grow more slowly, so the colonies they make are smaller than normal colonies. They are petite.
Plating is good for looking at yeast health, even if you don’t use the yeast from the plate. There are a couple of ways you can do it. The main thing is that you want to isolate single cells to examine the colonies after they grow big enough. You want the colonies to be smooth, round, and uniform in color. Two different strains may have different growth patterns, but you’ll become familiar with them.
The easiest thing to do might be to streak for singles. You put a small dot of yeast on the plate and smear it around. I could go into detail but MB has it covered here, under “Agar Plates”
The other option is to dilute it so the liquid you add to the plate doesn’t contain many cells. It can be hard to do at home because it is difficult to spread the liquid around without a sterile spreader and you would tend to add too much liquid so the yeast starts growing while it is evaporating, which causes smeared colonies.
Anyway, I’m trying to figure out if 1450 has a tendency to become petite or if I just have bad luck.
Cool, thanks. If nothing else, I might get some petri dishes and make up some plates the next time I’m making slants. Could be fun to check it out although, if it makes me want to go out and get a microscope, somebody’s gonna be in big trouble.
Now that makes me to start playing with yeast again.
About the only thing a scope is good for in a brewery is viability staining or counting with a hemocytometer. Most breweries don’t have them at all.
My issue in the brewery is how to scale up pitch from 5 gallons to 160 gallons.
I need to have 5 liters of slurry fro 5 BBL (lagers) and 10 liters for 10 BBL.
How much slurry can you save from your typical 5 BBL batch when it is done fermenting? Or are you talking about building up to a pitchable quantity from a smack pack? Getting to 5 liters would sure be a problem, but if you did a smaller batch in the interim it would help. Sounds like a pita though.
From 5 BBL I get about 10 liters of slurry.
I thought I would be growing yeast on my own from the beginning but now I am leaning to buy it.
I could buy smaller pitch and brew 2BBL one day and 5 BBL next day but it looks like a lot of work.
I think I will just buy 5 liters next time I need it.
Good to know, thanks. I would lean towards buying too, since you can be sure it is in good condition and it saves a lot of work. And of course, schedule your brew as much as possible to reuse yeast, since that will save money too.
If petite means they would be less active, then I’m pretty sure the 22-month-old 1450 I grew up did not go petite. My setup uses a one-hole stopper on the better bottle with about four feet of 3/4 inch blowoff tubing to a two-hole stopper on a 2-liter flask with a one piece airlock in the other hole. About 24 hours after pitching, the 1450 had blown off so much that it filled the blowoff tube, the flask, and came out the airlock all over the floor. Doesn’t sound like the 1450 was petite to me 
Thanks for the update
I still haven’t had a chance to plate mine out, I’ve got no lab for the time being.