Re-using already used Yeast

[john.west]

When making a simple ginger beer brew, the yeast sediment that ends up
at the bottom, i'm wondering if its a good idea to re-use it to start a
fresh brew ?
Some time ago, i read that 'used' yeast sediment would actually start a
new brew 'faster' than using fresh yeast, since it has already gone
through some of the fermenting processes. Is this true?
Are there any advantages at all, to re-using this already used yeast ?
Thanks.

[Joerg]

Post by john.west
When making a simple ginger beer brew, the yeast sediment that ends up
at the bottom, i'm wondering if its a good idea to re-use it to start a
fresh brew ?

I don't brew ginger beer but all sorts of other beers and do this all
the time. So far only with beers that use US-05 yeast. I go up to three
uses but some breweries do a lot more.

Post by john.west
Some time ago, i read that 'used' yeast sediment would actually start a
new brew 'faster' than using fresh yeast, since it has already gone
through some of the fermenting processes. Is this true?

Yes, that is my experience. Lag times with dry US-05 are usually 24h and
more. With harvested years it's a few hours.

Post by john.west
Are there any advantages at all, to re-using this already used yeast ?

Saves money and starts faster. It is not "used yeast" though. Yeast
makes lots of yeastie babies when it works on the wort. Therefore, when
I take the trub of a Koelsch or similar beer I place that into two or
more santized jars, into the fridge. On brew day I usually brew two
beers and I take one jar out an hour or so before the worts is cooled
down, depending on outside temperatures. Then I use some of the
light-brown and white top portion and slop it into the wort. The rest
goes back in the fridge. Same with the other jar in the afternoon for
the 2nd beer.

Now I am still not done. The remaining trub is turned into sort of a
sourdough, rises, then is mixed into bread dough, we let that rise
overnight and the next day I bake that over a hot wood fire. Yum! Anyone
who loves German bread will most likely not be able to stop eating. This:

https://delishably.com/baked-goods/SALLIEANNES-TRUB-BREAD-A-Wonderful-Yeasty-Bread-Made-Using-Beer-Trub

Ours is more flat and baked over wood fire so it has a nice dark, thick
and crunchy crust. We like our bread crunchy.

Don't use yeast harvested from darker or hoppier beers on brew that is
lighter and less hoppy. For example, for three-generation usage Koelsch
-> Pale Ale -> IPA is ok. Stout -> Pale Ale or IPA -> Cream Ale is not ok.

Make sure to be sanitary at all times. If I misjudge the temperature and
the harvested trub in the jar might end up too cold at the end of
wort-chilling I gently warm it up by cupping my hands around it while
watching the brew kettle. When you see stuff jetting around in the jar
it's ready.

[baloonon]

Post by Joerg
Don't use yeast harvested from darker or hoppier beers on brew
that is lighter and less hoppy. For example, for three-generation
usage Koelsch -> Pale Ale -> IPA is ok. Stout -> Pale Ale or
IPA -> Cream Ale is not ok.

I'm not sure that's such a big deal, assuming you're not leaving a ton of
hops behind in the sediment and you've let the yeast settle then poured off
most of the remaining sludgy beer. Assuming the volume is something like a
quart, the amount of residue from a dark beer shouldn't be much and it
ought to be stuff that settles to the bottom anyway.

I'd definitely be careful if it was something aged with oak, spices, smoked
malt, or anything else with a potent presence. It can't hurt to be careful
with the progression of beers pitched on reused yeast, though.

[Joerg]

Post by baloonon

Post by Joerg
Don't use yeast harvested from darker or hoppier beers on brew
that is lighter and less hoppy. For example, for three-generation
usage Koelsch -> Pale Ale -> IPA is ok. Stout -> Pale Ale or
IPA -> Cream Ale is not ok.

I'm not sure that's such a big deal, assuming you're not leaving a ton of
hops behind in the sediment and you've let the yeast settle then poured off
most of the remaining sludgy beer. Assuming the volume is something like a
quart, the amount of residue from a dark beer shouldn't be much and it
ought to be stuff that settles to the bottom anyway.
I'd definitely be careful if it was something aged with oak, spices, smoked
malt, or anything else with a potent presence. It can't hurt to be careful
with the progression of beers pitched on reused yeast, though.

Yeah, I might be overly cautious here. Hops I leave in the brew kettle
as best as I can, by siphoning into the fermenter instead of dumping the
wort in. I also try not to stir up too much towards the end of chilling.

In the jars there are in essence three layers after they had a few hours
in the fridge. A trub sludge at the bottom filling about half the jar or
more, a very thin white layer above that (this is the newborn yeast as
far as I know), then beer/water above that. The water I sometimes need
to dissolve the trub enough so I can pour it over into the jars. When I
tilt such a jar things immediately mix back into each other so
inevitably some of the trub plops into the new wort.

That trub part contains lots of taste. We always bake bread from that
and wit each bread you can immediately taste which kind of beer int came
from. With Stout and Dark Ales you can even see it, the bread is very
dark. And oh so tasty ...

[baloonon]

Post by Joerg
That trub part contains lots of taste. We always bake bread from that
and wit each bread you can immediately taste which kind of beer int
came from. With Stout and Dark Ales you can even see it, the bread is
very dark. And oh so tasty ...

If it's old yeast, do you have to proof it at all, or do you find that a
jar will stay active in the fridge for a while?

What's the volume of yeast (approximately) that you use per what volume of
flour?

[Joerg]

Post by baloonon

Post by Joerg
That trub part contains lots of taste. We always bake bread from that
and wit each bread you can immediately taste which kind of beer int
came from. With Stout and Dark Ales you can even see it, the bread is
very dark. And oh so tasty ...

If it's old yeast, do you have to proof it at all, or do you find that a
jar will stay active in the fridge for a while?

It's not old, it is the "newborn" yeast fresh from a primary from which
I just transferred the beer to secondary. Once harvested it never spends
more than a week inside the fridge. Not sure what constitutes proof but
when I take it out and it starts shooting little comets inside the jar I
consider it potent enough to start a new beer with.

Some brewers said it stays fresh for 2-3 weeks in the fridge. Longer if
you extract it from the harvested trub.

Post by baloonon
What's the volume of yeast (approximately) that you use per what volume of
flour?

If we use the whole trub from a 5-gallon batch for bread we add 1-1/2
cups of flour for the starter and later 4 cups of flour for the bread
dough. Proportionately less if I siphon some off for a new beer batch.

I take about 1/3rd of the jar contents per beer batch and if I have to
start two batches from the same harvested yeast batch my wife mixes in
some harvested trub (with yeast in there) from the other beer. I always
brew two beers simultaneously so we can "rob Peter to pay Paul".
Sometimes the other beer is a Belgian whose harvested yeast I cannot use
for a Koelsch or Cream Ale.

When she makes the bread dough some regular bread yeast gets added as
well. So the starter dough rises just from the newborn brewer's yeast
and the final dough is helped by bread yeast.

We don't make the bread very fluffy, we like it more dense.

In case anyone tries the recipe: Forget about using a li'l kitchen hand
mixer. It could burn up. I take one of the kneeding hooks and clamp it
into the chuck of my Ryobi cordless drill. Its Li-Ion battery is good
for two such bread doughs, then needs a swap or re-charge.