HOMEBREW Digest #5312 Fri 28 March 2008

 

	FORUM ON BEER, HOMEBREWING, AND RELATED ISSUES
		Digest Janitor: pbabcock at hbd.org


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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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