"Yeast clean up after themselves" - Home Brew Forums

Register Now!
Home Brew Forums > Home Brewing Beer > General Beer Discussion > "Yeast clean up after themselves"

Reply
 
Thread Tools
Old 02-07-2010, 05:00 AM   #1
DaveAllen
Recipes 
 
Nov 2009
SC
Posts: 111
Liked 1 Times on 1 Posts



I see this repeated numerous times here, but I'm not sure I understand the science behind this statement. Any enlightened responses?

 
Reply With Quote
Old 02-07-2010, 05:32 AM   #2
Hermit
Recipes 
 
Nov 2009
Alternate Universe
Posts: 2,281
Liked 72 Times on 61 Posts


Yeah. I'd be interested too. People say to leave the beer in the primary for a month instead of using a secondary but what good are the yeast that have decided to go dormant and lay on the bottom?

 
Reply With Quote
Old 02-07-2010, 06:47 AM   #3
Dr Malt
Recipes 
 
Aug 2005
Pacific Northwest
Posts: 305
Liked 14 Times on 14 Posts


I am not familiar with that statement, but in fermentation, yeast produce several chemical compounds that they later reassimilate and metabolize. One such compound is diacetyl which gives beer a distinct buttery, butterscotch note. This maybe what is being referred to in this statement.

Dr Malt

 
Reply With Quote
Old 02-07-2010, 07:00 AM   #4
mordantly
Registered User
Recipes 
 
May 2008
Westside..... CenCal - the country that'll never take away my guns or money !!!!!!!!!!!!!!!!!!!!!!!
Posts: 3,865
Liked 13 Times on 13 Posts


as DM said, and other chemicls too.

 
Reply With Quote
Old 02-07-2010, 07:01 AM   #5
DaveAllen
Recipes 
 
Nov 2009
SC
Posts: 111
Liked 1 Times on 1 Posts


Interesting. Yeast "reassimilate and metabolize" diacetyl? That's fascinating. I'd love to hear more about that.

 
Reply With Quote
Old 02-07-2010, 07:08 AM   #6
GilaMinumBeer
HBT_LIFETIMESUPPORTER.png
 
GilaMinumBeer's Avatar
Recipes 
 
Jan 2008
Posts: 58,463
Liked 7454 Times on 6109 Posts


Quote:
Originally Posted by DaveAllen View Post
Interesting. Yeast "reassimilate and metabolize" diacetyl? That's fascinating. I'd love to hear more about that.
Diacetyl rest brother. A process done to all lagers.

 
Reply With Quote
Old 02-07-2010, 07:11 AM   #7
Rushis
Recipes 
 
Nov 2009
Pasadena, CA
Posts: 289
Liked 4 Times on 4 Posts


Some metabolic sideproducts are utilized by the yeast after they have exhausted the simplest nutrient sources. Diacetyl and acetaldehyde are typical examples. There might be some metabolism of various esters, but probably to a minimal degree.


 
Reply With Quote
Old 02-07-2010, 07:13 AM   #8
Brewsmith
 
Brewsmith's Avatar
Recipes 
 
Aug 2005
Torrance, CA
Posts: 6,252
Liked 62 Times on 58 Posts


Aceteldehyde also. It's part of the process to making ethanol. Racking yeast too early will leave that green apple characteristic.
__________________
Fermenting:#160 Apollo/Calypso Pale Ale
Kegged:#153 Old Helicon Barleywine 2013, #157 Irish Red, #158 Mosaic IPA, #159 Bravo/Delta ESB
Up Next:Brown Porter, American Stout, Imperial Stout
My Recipes
Tuba Sonata

Smith & Co. Custom Tap Handles

 
Reply With Quote
Old 02-07-2010, 07:44 AM   #9
lamarguy
 
lamarguy's Avatar
Recipes 
 
Aug 2008
Austin, TX
Posts: 1,653
Liked 25 Times on 24 Posts


It's important to note that only healthy yeast will "cleanup" fermentation byproducts (i.e., chemically convert a certain percentage of undesirable chemical compounds with a low flavor threshold to one or more compounds with a higher flavor threshold).

For example, if you conduct a poor fermentation (e.g., significantly under-pitching), the yeast will not be able to reduce the offending compounds to a satisfactory degree.
__________________
Doggfather Brewery

Planned: Lambic, American IPA
Fermenting: 6 gals of 1.090 stout (Belgian) & 6 gals of 1.090 stout (English)
Tapped: Berliner Weisse, Black English IPA, German Pils, & Live Oak Primus

 
Reply With Quote
Old 02-07-2010, 08:24 AM   #10
mordantly
Registered User
Recipes 
 
May 2008
Westside..... CenCal - the country that'll never take away my guns or money !!!!!!!!!!!!!!!!!!!!!!!
Posts: 3,865
Liked 13 Times on 13 Posts


i don't notice any flavor concerns when i pitch about 250-500mL worth of yeast slurry per 5 gallons. yet when done we get over 2L of slurry. which tells me that is "under" pitched if there is such a thing. i bet one has to just add the smack pack to 5 gallons to have any issue with that?

 
Reply With Quote
Reply
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
simple quesion about "Easy Clean" zodiak3000 Beginners Beer Brewing Forum 5 02-07-2013 07:42 PM
How much does beer "clean up" in fermenter? deputybrewer Beginners Beer Brewing Forum 9 02-23-2009 02:23 PM
"Let beer 'clean up after itself' in primary"...what does that mean?? Kitchi Gumee Beginners Beer Brewing Forum 7 06-11-2008 05:33 PM
Thoughts on a "clean out the hops" pale ale cweston Recipes/Ingredients 2 03-02-2006 11:58 PM
Anyone Familiar with "Beer Clean Sanitizer"? Wolf Equipment/Sanitation 2 03-01-2006 01:45 PM


Forum Jump