HOMEBREW Digest #5311 Thu 27 March 2008

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  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 Return to table of contents
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 Return to table of contents
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 Return to table of contents
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 Return to table of contents
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 Return to table of contents
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 Return to table of contents
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