HOMEBREW Digest #5312 Fri 28 March 2008


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  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 Return to table of contents
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. Return to table of contents
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