Starter from harvest question

[oliver]

I recon the browning is oxidation that supposedly causes the beer to darken over time.

I thought that too, but in sealed mason jars? I guess oxygen went in with it.

Next question is, what oxidizes? Is it just the diluted wort that oxidizes? Or does oxidation have some kind of effect on yeast?

 

[Nosybear]

I thought that too, but in sealed mason jars? I guess oxygen went in with it.

Next question is, what oxidizes? Is it just the diluted wort that oxidizes? Or does oxidation have some kind of effect on yeast?

Oxidation doesn't require oxygen! Oxidation is any reaction where the material gives up electrons, oxygen being a very powerful oxidant, accepting two electrons very readily.. But the browning is cells dying off and their contents oxidizing, resulting in lower viability yeast and off-flavors.

 

[oliver]

Oxidation doesn't require oxygen! Oxidation is any reaction where the material gives up electrons, oxygen being a very powerful oxidant, accepting two electrons very readily.. But the browning is cells dying off and their contents oxidizing, resulting in lower viability yeast and off-flavors.

so it oxidation does have an effect on the yeast? Meaning, yeast that goes through another round of fermentation that has been oxidized in the jars will give off some off flavors?

 

[Nosybear]

so it oxidation does have an effect on the yeast? Meaning, yeast that goes through another round of fermentation that has been oxidized in the jars will give off some off flavors?

It doesn't go through another fermentation, they yeast cells start to die from lack of food and storage in a poisonous environment. When the yeast cells die, their cell walls rupture, releasing their contents into the beer. Some of those contents oxidize, either as a result of oxygen or other oxidants. Key is that cells are dying - your preserved yeast is losing viability for the next pitch. You could take a small sample and propagate it back up and as long as you weren't propagating mutants or bacteria, it would be fine.

 

[oliver]

It doesn't go through another fermentation, they yeast cells start to die from lack of food and storage in a poisonous environment. When the yeast cells die, their cell walls rupture, releasing their contents into the beer. Some of those contents oxidize, either as a result of oxygen or other oxidants. Key is that cells are dying - your preserved yeast is losing viability for the next pitch. You could take a small sample and propagate it back up and as long as you weren't propagating mutants or bacteria, it would be fine.

yeah I'm making starters with them before pitching.

 

[Nosybear]

yeah I'm making starters with them before pitching.

The conventional wisdom is to make starters from harvested yeast prior to use, at least just enough to reactivate the yeast. I'm sure there are some who just dump it in and get good results, though....

 

[Hawkbox]

What I've started doing is making a starter with my stored yeast, then using about 75% of it in the wort with the other 25% going back into a mason jar for the next starter. I use harvested wort from my mash tun usually that I boiled for a few minutes and then froze. So far it's worked really well.

 

[Mase]

Hmmm.... I haven't started yeast harvesting yet. But would it be a better idea to save some of your yeast from the manufacturer (25%) and then spin up the rest for the batch you are brewing. Then grow the 25% and keep doing that instead of using yeast from a full blown brew that has all kind of other debris in it and most likely isn't the same yeast anymore. That way, you should (in my thinking), still be starting from the same yeast strain as you purchased.

 

[Hawkbox]

That's exactly what I do. The only one that isn't a starter from a package is one I reclaimed from a commercial beer just to see if I could.

I'm on my 4th generation for some of them but as I use clean starters I don't expect much in the way of issue for a while. I do brew quite a bit though so I may build new starters once a year or so.

 

[Beer_Pirate]

The conventional wisdom is to make starters from harvested yeast prior to use, at least just enough to reactivate the yeast. I'm sure there are some who just dump it in and get good results, though....

Guilty! (and lazy) On occasion I'll throw a pinch of dextrose in there a few hours before pitching, but otherwise I just swirl and dump from the jar. It'll likely bite me in the ass one day.

 

[Hawkbox]

I've done that more than once, seems to work fine. My only thing is I usually want to have some for the next batch, hence the starter.

 

[Nosybear]

Guilty! (and lazy) On occasion I'll throw a pinch of dextrose in there a few hours before pitching, but otherwise I just swirl and dump from the jar. It'll likely bite me in the ass one day.

Likely not, if the yeast is fresh enough. A starter is a bit of an excess of caution but it's what the book says to do, whatever the book may actually be....

 

[Hawkbox]

Some guy what knows a guy said...

 

[Nosybear]

...or whoever wrote the Book.

 

[GFHomebrew]

When storing the yeast in that jar oliver 02 was sitting at the top of it hence the darkening or the beer. I think brulospher has an exbeeriment on this.

My 2c if you have the time you cant go wrong with a starter. If not just pitch the previous batches slurry (if using same yeast).

 

[Hawkbox]

That's something I've never had the nerve to do, but I've heard of people just transferring fresh wort right into the yeast cake from the previous batch.

 

[GFHomebrew]

That's something I've never had the nerve to do, but I've heard of people just transferring fresh wort right into the yeast cake from the previous batch.

Yeah don't use the entire cake except if culturing it up for a crazy big beer like a Imperial Stout or barley wine.
Whilst my stir plate was out of action I got away with just pitching slurry for quite a few brews one lager included. They all attenuated well and cleared well and there is in my opinion nothing better to store your yeast under than the brew it just Finnished.

But like all things brewing cleanliness is next to godliness.
I had a 4 out of 4 success rate in my biased books.