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HOMEBREW Digest #5311
HOMEBREW Digest #5311 Thu 27 March 2008
FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
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Contents:
Re: Olive Oil Addition to Yeast as an Alternative to Wort Aeration (Fred L Johnson)
olive oil etc (Matt)
Re: Olive Oil Addition to Yeast as an Alternative to Wort Aeration (steve alexander)
RE: english yeast strains ("Jim Dunlap")
Re: Olive Oil Addition to Yeast as an Alternative to Wort Aeration ("Steve.Alexander")
Stir Plate Aeration ("LANCE HARBISON")
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Date: Wed, 26 Mar 2008 19:38:58 -0400
From: Fred L Johnson <FLJohnson52 at nc.rr.com>
Subject: Re: Olive Oil Addition to Yeast as an Alternative to Wort Aeration
Regarding the ability of yeast to use externally provided
triglycerides, I should have said in my last post that although some
species of yeast do have the ability to secrete triglyceride lipase,
hydrolyze the fatty ester bond with the glycerol backbone, and thus
could take up fatty acids from added triglycerides, S. cerevesiae is
not one of them.
So far I've only been able to find an abstract that indicates that
olive oil contains 0.2-6.14% of its weight as free fatty acid. I must
admit that 6% is far more than I expected. 0.2% is more in line with
what I expected.
In Hull's study, he incubated the yeast (unstated amount) harvested
from a previous fermentation with olive oil for five hours prior to
pitching the yeast into a new batch of wort. I could not determine
exactly what the concentration of olive oil in the incubation was
because the olive oil was added at a level of 1 mg per 67 billion
cells rather than adding it on a volume basis. According to Hull,
this came to something like 15 mg olive oil/L of yeast in one
experiment. In other experiments in the paper, Hull increased this to
1 mg per 50 billion cells and 1 mg per 25 billion cells. It appears
that these incubations were then added to the entire 360 hL, 720 hL,
or 2100 hL batches of wort in the various experiments.
I estimated that the lowest addition was in the neighborhood of 15
grams olive oil added to the yeast from a previous fermentation. That
would be the rate rate of 1 mg olive oil per 67 billion cells if one
assumes a pitching rate of 2 billion cells per liter per degree Plato
or about a half gram of free fatty acids per 670 hL batch, assuming
3% of the olive oil is free fatty acid.
Fred L Johnson
Apex, North Carolina, USA
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Date: Thu, 27 Mar 2008 07:02:13 -0700 (PDT)
From: Matt <baumssl27 at yahoo.com>
Subject: olive oil etc
Fred says "For all we know adding nothing would have produced the exact
results reported for addition of olive oil."
I haven't read the paper so I don't know for certain that this is true,
but anyway I agree with the sentiment. If New Belgium props up fresh
yeast using a nice yeast propagator (and/or "refreshes" any repitched
yeast with O2 and sugar), which wouldn't surprise me, then they could
very well not need to add oxygen or olive oil (nor extra sterols) to
get a good fermentation. Like quite a few other homebrewers these
days, I take that approach all the time.
Fred also says "I'm pretty certain that there is no mechanism for yeast
to use triglycerides."
I thought that in the discussions before, between Fred and Steve, on
this topic it had come out that there's evidence yeast CAN use the
triglycerides. Am I mistaken?
Matt
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Date: Thu, 27 Mar 2008 10:27:59 -0400
From: steve alexander <steve-alexander at roadrunner.com>
Subject: Re: Olive Oil Addition to Yeast as an Alternative to Wort Aeration
Fred Johnson, as is usually, brings up some excellent points wrt
OliveOil in brewing.
> And I've said this before, it is very unlikely that the bulk of the
> olive oil (triglyceride) has anything to do with the results. I'm
> pretty certain that there is no mechanism for yeast to use
> triglycerides.
I think you are right; or close enough. Taylor,Thurston,Kirsop
[JIB v85, pp219-227] used lipids extraced from spent grain. The grain lipid
analysis was 28% freeFA, 18%phospholipid, 3% mono-glyceride, 7%
diglyceride, 43% tri-glyceride and no more that 2% sterol. Also this study
performed tests adding pure lipid components to wort.
Removing the triglyceride from the mix had only a tiny impact on
fermentation
performance, however the removal of triglyceride cause a small decrease in
final UFA within the yeast. They suggest "slight incorporation of
triglycerides,
or the component fatty acids".
There are some other papers where truly gross amounts of FAs (often as
tween80, several ounces volume per 5gal) to the fermenter.
I had a conversation years ago (unclear if it was in this forum or
offline) where
Charlie Scandrett discussed a paper that described lipid transport from
trub to yeast.
I'd like to find that reference but I'm short of time till mid-April.
> The presence of a small amount of nonesterifed fatty
> acids in olive is perhaps the only source that the yeast could
> actually take up. If you're trying to add polyunsaturated fatty acids
> to wort, adding olive oil would appear to be a poor way to do so. In
> the next post, I'll try to find out the content of free fatty acids
> in a typical olive oil.
>
By law Class A olive oil must have <1.4% free FA , Class C OO < 3%. Free
UFAs
are rapidly oxidized producing off-rancid flavors, so often commercial OO is
"neutralized" to remove free FAs. So we are looking at 97+% ineffective
N-glycerides in OO.
-S
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Date: Thu, 27 Mar 2008 07:39:41 -0700
From: "Jim Dunlap" <jdpils at comcast.net>
Subject: RE: english yeast strains
Matt,
I personally like Wyeast 1968 which I believe has a Fuller's origin and is
also available from White labs as WLP-002. Some say it settles too fast and
clumps leaving some residual sugar. Typically I buy an "XL" pack (I prefer
over WLP-002) and direct pitch into 5 gallons of ESB. Typically I will go
from 1.052 - 1.056 to 1.014 where yeasts such as American Ale or Scottish
would take the same wort to 1.010. On the subsequent pitchings I find the
difference to diminish given the correct ferment temp is selected for each
yeast. The key points I have found and would like others to share their
experience is this yeast is to tip the carboy and roll it to agitate the
sediment every day. I have never had a settling issue. Ferment between 66
- 70 F. This yeast does not like cold temps and gets very fruity hotter.
Note you ambient temp is 4 degrees cooler than a glass carboy just sitting
in a room under a blanket. It will ferement in 2 - 5 days at this temp, but
do not chill or rack for another 2 or 3 days to get rid or diacetyl inad its
precursors. So typiocally I wait one week to two to rack to secondary. You
can also directly keg after primary. I do not care for this yeast for beers
over 1068 as it produces too many esters, etc. I have never tried a "super
slurry" as defined by 1 quart or more of compacted yeast without any liquid
and ferement at say 62 - 64 or bring up from colder temps to start because I
am happy with the results. I would also say that we frequently pick this
yeast out in ESB's as the best of four or five blind samples. I always pass
ESB tasting to my wife, her favorite beer and try different yeasts and
compare to Desceutes Mirror Pond Pale Ale (preferred daily beer) or Elysian
The Wise ESB (her absolute favorite but not an everyday beer cause its too
strong)
There are other yeasts I like for ales including Pacman, Wy1728, White Labs
Southwold, Irish ale, WLP029. I rearely use 1056 or its equivalents. AS
for fruity there are man Wyeast and White Labs English Ales.
Cheers,
Jim
------------------------------
Date: Thu, 27 Mar 2008 14:23:35 -0400
From: "Steve.Alexander" <steve-alexander at roadrunner.com>
Subject: Re: Olive Oil Addition to Yeast as an Alternative to Wort Aeration
The other toad in the punchbowl wrt freeFA additions to the fermenter ....
Free FAs, and particularly PUFAs go stale so fast that we'd have to
handle these carefully. Also salts of FFAs and compounds like tween
(sorbitan+oleic) have a detergent effect that could potentially degrade
cell membranes. It seems reasonable that solubilizing free FAs should
cause havoc w/ the lipid bi-layer.
Am I wrong about the detergent disrupting the membrane ?
Any thoughts Fred ?
-S
------------------------------
Date: Thu, 27 Mar 2008 18:21:29 -0500
From: "LANCE HARBISON" <harbison65 at verizon.net>
Subject: Stir Plate Aeration
I have recently gone to using a stir plate. In the past I have experimented
with: 1) constant aeration with the stone submerged, 2) constant aeration
with the stone suspended just above the wort, and 3) periodic (every 6 - 12
hours) submerged aeration. I make between 1 gallon and 2 gallon starters
using a 2-step process. Would there be any benefits or detractions of the 3
methods?
Lance Harbison
Pittsburgh
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End of HOMEBREW Digest #5311, 03/27/08
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