Reusing Yeast Health question

Before I fully knew (or cared) to store yeast slurry, I would just bottle up the yeast and trub in regular 12 oz bottles and put them in the fridge. Most would gush when I opened them. I still have quite a few left but usually don't use them.

I used one for a 2.5 batch of Kolsch, did a starter and It turned out ok. im pretty sure the off -flavors in that one were just from the old discounted hops I used.

Anyways, my question is: if I want to use some old (8+ months old) bottles yeast/trub mixer on an upcoming brew, would I be OK with just doing a big starter?
Will that generate enough reproduction to have a healthy yeast colony again?
Thanks

 

Btw I plan on pitching in a small 1.052 OG beer

 

You'd probably have to do a couple of steps of starters, as your viability is going to be quite low. I'd also be concerned about off-flavours from autolysis from yeast that old. I tend to dump any yeast that's been in my fridge for more than 2 months. If I were in your shoes, I'd just buy a fresh smack-pack of Kolsch yeast rather than risking a whole batch of beer on yeast older than my nephew.

 

I've stored and used yeast slurry in the same manner with success. Yeast can remain healthy being stored under beer with refrigeration. Making a starter or multiple step starter to restore vitality and build up numbers is needed, though. By Mr. Malty your 8+ month old yeast probably has about 10% viable yeast cells remaining at this point.

 

I second kombat, no reason to risk the brew. Buy new pack and use that.

 

Hmm, at 10% it seems like I'd spend just as much on extract building up a starter as just buying a new pack!