Newbie questions

I have read about using the yeast cake and have some questions.

First, is this the layer of sludge that drops to the bottom of my fermenter? If so, what is the best way to harvest it and store it? Or is it a by product of making a yeast starter?

Second, if it is harvested from a fermenter, does it need to be used with a similar style of beer, i.e. can the yeast from a porter or stout be used with a marzen or a wee heavy?

And how many times can one harvest and reuse the yeast?

Finally, why would I do this considering that Safale US-05 is only around 3 bucks a pack? No sarcasm here, I really want to understand what this is, how to do it and the reasons surrounding doing it.

Thanks,

Rick Near Atlanta

You might be mixing up two concepts.

First, yes, the yeast cake is the sediment on the bottom of your fermenter. That sediment does include other trub ingredients though - any hops that made the transfer into your fermenter wind up in there, as well as other proteins that fall out of suspension as your beer clears.

One method of re-using that cake is pitching onto an existing yeast cake, or part of one. The main idea is that you can't keep that cake for very long (it'll be OK refrigerated for a day or two, but that's about it). From personal experience, I pitched about a pint of yeast cake/slurry from a brown ale into two other batches - both quite difffernt styles - and they came out beautifully. If I recall, I racked the brown ale to a keg one day and transferred a bunch of slurry into a growler then placed that growler in the fridge. I brewed up the other two beers the next day.

The other method, and one where you can keep the slurry for considerably longer, is yeast washing - check out the sticky on that here, for all the details you could ever ask for.

Both methods do have limits; once you get beyond so many fermentations (I keep reading 5 or 6 is the outside limit), you start to risk mutations in the strain and you get less predictable results.

As for why folks do it - typically, it's not done for dry yeasts for exactly the reason you cite: to save $3 a pack, it's not worth the effort. However, liquid strains can get a lot more expensive, particularly if you wind up pitching multiple vials/smack packs, and some of those strains are only available for short time spans, so this is a way to keep getting more of that yeast after you can no longer buy the stuff.

Great explanation.

Thanks much for explaining that. Using much beyond US-05 or US-04 is still a couple of months out for me but this adds to the knowledge I am acquiring. Also, thanks for the link to the yeast washing post.

Rick Near Atlanta

Currently Bottled:
Peach Marzen
Spiced Marzen
Sorghum Porter
Raspberry Porter

Brewing next week:
Oaked Imperial Stout
Marzen (Daughter is adjusting her Peach Marzen)
Rye Stout
2 batches of Apple Cider
2 Double Bocks