Author Topic: lack of attenuation...here we go again...  (Read 1755 times)

S. cerevisiae

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Re: lack of attenuation...here we go again...
« Reply #30 on: November 24, 2015, 02:16:42 AM »
Brewinhard beat me to chase. The source of your problem is borderline aeration.  Dry yeast does not require much in the way of aeration because it is propagated aerobically below the Crabtree threshold; therefore, it goes into a fermentation will with fully-charged ergosterol and unsaturated fatty acid (UFA) reserves.  Cropped yeast is an entirely different animal.  Cropped yeast has low ergosterol and UFA reserves.  Yeast cells use O2 to synthesize these compounds, which, in turn, are used to repair and build plasma membranes.   The plasma membrane is what controls how well a cell can pass nutrients and waste products through the cell wall.  These reserves are shared with daughter cells during the fermentation.  Low dissolved O2 coupled with quiescent yeast cells is a recipe for high terminal gravity.

If you have an old broken racking cane or length 3/8" copper tubing lying around, you can make a poor man's aerator by drilling a bunch holes downward at a 45-degree angle.  The aerator is inserted into a piece of tubing that runs from your ball valve on your kettle to your fermentation vessel. Wort mixes with air when it passes through the holes.  It is best to use this device in a non-drafty room.  A shroud can be made by drilling a hole in the closed end of a prescription vial and inserting a rubber grommet with a 3/8" I.D.  The closed end slides over the aerator, closed end up, such that the holes are inside of the prescription vial.  Sterile cotton is lightly packed into the open end.  The keyword here is lightly.  Air needs to be able to pass through the cotton.  The sterile cotton is there to collect dust.   I do not use a shroud.  I merely place the aerator down into a carboy.  The air inside a freshly sanitized carboy should be relatively dust free, and a carboy is under positive pressure while it is being filled.


Poor Man's Aerator

« Last Edit: November 25, 2015, 02:03:45 AM by S. cerevisiae »

Offline BairsBrewing

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Re: lack of attenuation...here we go again...
« Reply #31 on: November 24, 2015, 03:20:16 PM »

Brewinhard beat me to chase. The source of your problem is borderline aeration.  Dry yeast does not require much in the way of aeration because it is propagated aerobically below the Crabtree threshold; therefore, it goes into a fermentation will with fully-charged ergosterol and unsaturated fatty acid (UFA) reserves.  Cropped yeast is an entirely different animal.  Cropped yeast has low ergosterol and UFA reserves.  Yeast cells use O2 to synthesize these compounds, which, in turn, are used to repair and build plasma membranes.   The plasma membrane is what controls how well a cell can pass nutrients and waste products through the cell wall.  These reserves are shared with daughter cells during the fermentation.  Low dissolved O2 coupled with quiescent yeast cells is a recipe for high terminal gravity.

If you have an old broken racking cane or length 3/8" copper tubing lying around, you can make a poor man's aerator by drilling a bunch holes downward at a 45-degree angle.  The aerator is inserted into a piece of tubing that runs from your ball valve on your kettle to your fermentation vessel. Wort mixes with air when it passes through the holes.  It is best to use this device in a non-drafty room.  A shroud can be made by drilling a hole in the closed end of a prescription vial and inserting a rubber grommet with a 3/8" I.D.  The closed end slides over the aerator, closed end up, such that the holes are inside of the prescription vial.  Sterile cotton is lightly packed into the open end.  They keyword here is lightly.  Air needs to be able to pass through the cotton.  The sterile cotton is there to collect dust.   I do not use a shroud.  I merely place the aerator down into a carboy.  The air inside a freshly sanitized carboy should be relatively dust free, and a carboy is under positive pressure while it is being filled.


Poor Man's Aerator



Could you do the same thing with the tubing?  I use an auto-siphon to rack from primary to secondary, but going from kettle to chill plate to primary I just have silicone tubing.  I'd love to put an inline sanitary O2 supply but not sure the CFO would approve the aforementioned transaction.

S. cerevisiae

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Re: lack of attenuation...here we go again...
« Reply #32 on: November 25, 2015, 02:12:37 AM »
A section of hard tubing works best. A new 3/8" racking cane is less than a $3.00 transaction.  If you ask around, you should be able to find someone who has part of broken one or an unused bottle filler.  The device is called a poor man's aerator for a reason.

Offline goschman

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Re: lack of attenuation...here we go again...
« Reply #33 on: November 29, 2015, 04:00:25 AM »
Kegged the beer today. FG after adding sugar was 1.018 so that make me feel a little bit better. Considering the high FG and Munich malt base, the sample tasted sort of thin and watery.
On Tap/Bottled: Euro Pale, Hazeless Daze IPA, Summer Gold, Dry Hopped Peach Cider       

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Offline brewinhard

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Re: lack of attenuation...here we go again...
« Reply #34 on: November 29, 2015, 06:38:16 PM »
Sugar additions can do that to the body and mouthfeel of a beer.  But I bet once you get that one carbonated up properly that it will be tasting pretty good.  Just a guess.... :D