Generation of Yeast from Starter - Home Brew Forums

Register Now!
Home Brew Forums > Home Brewing Beer > Fermentation & Yeast > Generation of Yeast from Starter

Reply
 
Thread Tools
Old 02-10-2013, 12:15 AM   #1
el_caro
Recipes 
 
Feb 2011
, Australia
Posts: 607
Liked 33 Times on 28 Posts



I am a little unsure about the generation of yeast that have been grown in starters and never fermented out a beer as such.
For instance I take a vial or smackpack of yeast and put it into a starter then rinse and store the yeast in a couple of containers. Is this still first generation yeast?
If I take one of those containers from the fridge and grow it up in a starter and store some of the yeast again then what generation is that stored yeast?

If you step up starters rather than make a larger one does that have any impact on what generation the yeast is?

 
Reply With Quote
Old 02-10-2013, 01:14 AM   #2
LLBeanJ
HBT_SUPPORTER.png
 
LLBeanJ's Avatar
Recipes 
 
Feb 2012
Windsor, CO
Posts: 2,630
Liked 591 Times on 431 Posts


As I understand it, the first starter out of the vial or smack pack is the first generation. If you split that starter off and make another starter later, that would be the second generation. Step-ups for a single starter are the same generation.

I'm sure somebody will correct me if I'm wrong.

 
Reply With Quote
Old 02-10-2013, 03:42 AM   #3
el_caro
Recipes 
 
Feb 2011
, Australia
Posts: 607
Liked 33 Times on 28 Posts


Why would stepping up a starter not be a new generation same as creating a new starter at some time in the future? All that is actually happening is that wort is being fed to the yeast in both cases.

 
Reply With Quote
Old 02-10-2013, 05:10 AM   #4
acidrain
Recipes 
 
Jul 2012
Seattle, Washington
Posts: 2,080
Liked 181 Times on 156 Posts


Correct me if I'm wrong, but "generations" refer to yeast collected from batches of beer. Original pitch = gen 1, collect and re-use for next batch = gen 2, etc.
But...
If I step up a starter, split it and store it (like I always do), then once it's split and in the fridge, the clock is ticking. As it ages, the viability diminishes.
__________________
Keg #1: Brown Bomber Bourbon/Oak Vanilla Porter
Keg #2: The Bollocks ESB
Keg #3 Lawnmower APA
Fermenter: Empty
Bottled: Mjolnir Mead, Lazy Daze Hefe.

 
Reply With Quote
Old 02-10-2013, 08:44 AM   #5
el_caro
Recipes 
 
Feb 2011
, Australia
Posts: 607
Liked 33 Times on 28 Posts


Quote:
Originally Posted by acidrain View Post
Correct me if I'm wrong, but "generations" refer to yeast collected from batches of beer. Original pitch = gen 1, collect and re-use for next batch = gen 2, etc.
That is the confusing bit for me. If the yeast never makes beer but is just stepped up, rinsed and stored, is it still generation 1. And if I step that stored yeast up at a later date, rinse it and split it into two samples then what generation are those samples?

 
Reply With Quote
Old 02-10-2013, 02:06 PM   #6
LLBeanJ
HBT_SUPPORTER.png
 
LLBeanJ's Avatar
Recipes 
 
Feb 2012
Windsor, CO
Posts: 2,630
Liked 591 Times on 431 Posts


I haven't read any of the yeast books that are frequently mentioned on this site, assuming they even cover this subject, so I could be talking out my arse, but I think of it this way: anytime you significantly reduce the size of the colony and then build it back up, that in my mind would be a new generation. That's what happens when you split a starter. However, stepping up a starter is taking the same colony and growing it larger, so it's not a new generation with each step. The time lapse between steps also likely plays a role as well. If viability declines too much between steps due to excessive time lapse, then that could mean the difference between a single generation and two. My guess is there is a bit of grey area here.

Of course, there are certainly biological factors regarding growth phases and such that come into play as well, but that stuff is way over my head, so I just try to keep it simple so that my little brain can make some sense of it all. Perhaps one of the members who knows a lot more about yeast than I profess to know will step in and provide some much needed insight.

el_caro Likes This 
Reply With Quote
Old 02-10-2013, 08:12 PM   #7
el_caro
Recipes 
 
Feb 2011
, Australia
Posts: 607
Liked 33 Times on 28 Posts


Thanks Bean.

 
Reply With Quote
Old 02-11-2013, 03:00 AM   #8
Calder
Recipes 
 
Mar 2010
Ohio
Posts: 7,592
Liked 624 Times on 546 Posts


I'd call them all first generation.

A starter is low gravity and not much head pressure. It is relatively easy on the yeast.

 
Reply With Quote
Old 02-11-2013, 07:26 AM   #9
el_caro
Recipes 
 
Feb 2011
, Australia
Posts: 607
Liked 33 Times on 28 Posts


Quote:
Originally Posted by Calder View Post
I'd call them all first generation.

A starter is low gravity and not much head pressure. It is relatively easy on the yeast.
Thanks for your input Calder

 
Reply With Quote
Old 02-11-2013, 12:18 PM   #10
WoodlandBrew
HBT_SUPPORTER.png
 
WoodlandBrew's Avatar
Recipes 
 
Oct 2012
Malden, MA
Posts: 2,191
Liked 244 Times on 199 Posts


It's terminology. A new generation is spawned each time a cell buds. This happens 5-10 times in a normal fermentation. A new passage is created when yeast is moved from one media to another. The latter is more similar to what homebrewers refer to as a generation.

However,

What you are probably really interested in is how much the yeast has changed from the original strain. This is effected by conditions under which the yeast is propagated. In a 9P wort at 25C with constant aeration the yeast will change vary little with hundreds of cell divisions. In at 35P barley wine the same number of cell divisions can result in cells very different than the original strain.
__________________
The 2nd edition is now available: Brewing Engineering
Woodland Brewing Research Blog Applied Science for Better Beer.

TheOnionKnight Likes This 
Reply With Quote
Reply
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
does a yeast starter from washed yeast count as a generation? msa8967 Fermentation & Yeast 1 10-03-2012 01:01 AM
2nd generation yeast how to binaryman Fermentation & Yeast 4 05-10-2012 07:48 PM
3rd Generation Yeast Starter Question (w/pic) BradleyBrew Beginners Beer Brewing Forum 9 12-08-2011 12:28 PM
Washed Yeast (1st Generation) with no starter cox8611 Fermentation & Yeast 2 04-11-2011 04:58 PM
How much does yeast change from one generation to the next Challenger440 Beginners Beer Brewing Forum 6 01-23-2010 03:34 AM


Forum Jump