Month Old Yeast Cake

I have this old yeast cake that has been sitting in my frig for a month. My question is can I harvest the yeast and re pitch without making a starter?

DaTruf said:

I have this old yeast cake that has been sitting in my frig for a month. My question is can I harvest the yeast and re pitch without making a starter?

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I have the same question, but mine is 9 months old.

You guys are looking for someone to make a guess about the viability and cleanliness of your "unknown" stored yeast. 1 month will be much more viable than 9 months FWIW.

Most likely always best to make a fresh starter, on the other hand, what you have will likely work, but the results may vary as always (good, bad, indifferent), really up to you????

Whatever you do, smell it for freshness, if it smells like baby puke, toss it out, cheers!

Put it this way: let's say that you have 50% viable cells in there (I'm just making a number up). That means you would still have about 300-500 billion cells, which is more than enough to pitch a batch, but I really question their current health level.

Viability is important but so is vitality. Making a starter with lots of nutrients is going to be essential if you want to reuse any of those yeast. Even still, I wonder if I'm taking the easy road (read: less effective and ideal) when I reuse old yeast.

I have a question for any of you yeast biologists out there - let's say you save some reharvested yeast, but you know you're not going to brew for maybe 4-6 weeks. Would it be better to every week toss some of it and then grow up a small starter, or to let it sit as-is for several weeks, and then the week of the brew diligently make a couple good starters to build the health of the culture up? This question has been plaguing me.

I'd toss the 9 month and use the 1 month if it didn't stink like sulfer or vinegar. 9 months is too risky imo considering it sat there through summer heat.

If the smell is fine, pitch away! I've regularly pitched similar cakes after sitting in the fridge for 4-7 months - mine are less clean though, being just poured from my fermenter, no rinsing.

One time I was determined to make a dubbel, but there was a problem with the homebrew shop and they couldn't get my yeast in time. So my only other option was to use my friend's year old yeast. It was the 1762 strain. I decanted the liquid and poured the (mostly black) gunk into a 200mL starter. It was hard to tell if something was happening, but a few days later I decanted and added to a 1L starter. There was definitely some fermentation going on. A few days later I decanted and made a 2L starter for the final growth.

This was a pretty typical dubbel recipe, about 8% various crystal malts, some munich, wheat, and base malt, plus 10% sugar (caramelized at home). Pitched at 65, oxygenation via stone, used a heating pad to finish strong on fermentation, and I only got 72% attenuation. That would be pretty bad for this yeast WITHOUT the extra sugar!

So there's your lesson in viability vs vitality.

Thanks to everyone for your advice.