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HOMEBREW Digest #5312
HOMEBREW Digest #5312 Fri 28 March 2008
FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
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Contents:
Adding Fatty Acids to Wort (Fred L Johnson)
Olive Oil ("A.J deLange")
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Date: Fri, 28 Mar 2008 08:08:31 -0400
From: Fred L Johnson <FLJohnson52 at nc.rr.com>
Subject: Adding Fatty Acids to Wort
Steve Alexander provided us some great information on the free
fatty acid content of olive oil.
Steve also mentions the possibility that adding free fatty acids to
wort in a detergent could cause problems with the yeast membranes. On
this point, the detergent effect on yeast cells is entirely dependent
on the concentration of the detergent. Don't forget that the salts
of the fatty acids are themselves the detergent unless one adds fatty
acids or oils emulsified with another added detergent such as Tween,
which has been used in other studies.
Until we determine how much fatty acid we would actually want to add,
we can't know if this could have detergent effects on the cells. From
the amounts we've been talking about in the New Belgium studies, the
amount of fatty acids appears to be very small, and I seriously doubt
this amount would reduce yeast viability or heading properties of the
product. Adding triglyceride, on the other hand, could conceivably
affect heading properties, especially if one has to add a lot to
achieve a free fatty acid level high enough to benefit the yeast. In
this regard, Hull states that he did not see any detrimental effect
on foam retention in his olive oil additions.
Regarding Matt's comment on New Belgium propping up the yeast in a
propagator before pitching by adding fresh wort and oxygen, this was
not the case in Hull's studies. All of the yeast that was pitched had
come from the bottom of the fermentor from a previous fermentation
(and which had been stored with no additions (except for the addition
of olive oil in the case of the experiment). At the completion of a
standard full-batch fermentation, the fermentor was cooled and the
yeast was harvested from this batch within the next 48 hours and
placed in a storage vessel. The yeast spent up to 72 hours in the
storage vessel.
Control fermentations were aerated in line as usual and the stored
yeast was pitched with no other additions. Test fermentations were
not aerated in line, and olive oil was added to the yeast in the
storage vessel five hours prior to pitching. As I said, the full
batch of wort for these test fermentations was not aerated, although
no dissolved oxygen levels are reported in the control versus the
test worts in the fermentor, so we don't know how much oxygen the
various worts actually contained. I could not tell how much yeast was
actually pitched in any of the control or test fermentations.
Fred L Johnson
Apex, North Carolina, USA
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Date: Fri, 28 Mar 2008 08:47:07 -0400
From: "A.J deLange" <ajdel at cox.net>
Subject: Olive Oil
When looking at the Hull article remember that the hypothesis being
tested is: There are quality differences between beers brewed using
normal brewery practice of inline oxygen injection and beers in which no
inline injection is employed but whose yeast slurry has been treated
with olive oil. The null hypothesis is that there are no differences.
Though no formal statistical analysis is given (note that this is not a
refereed paper) the data presented tend to support the null hypothesis.
Another hypothesis (and the subject for another analysis) is: There are
differences in the qualities of beers brewed using the normal practice
of inline oxygen injection and those in which none is employed (no olive
oil addition this time). While it would be interesting to have this
hypothesis tested and it would indeed add information and a sense of
completeness to the article we can hardly ask them to sacrifice 360 hL
of their product to test a hypothesis that I think we all have a pretty
strong sense would be accepted. So while I'd love to see a third trace
on those spider diagrams representing no oxygenation or olive oil I
think we have to remind ourselves that this was not a laboratory
investigation but rather an attempt to validate the feasibility of a
change in a working brewery's process.
A.J.
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End of HOMEBREW Digest #5312, 03/28/08
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