maltbarleyhops
Well-Known Member
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Olive oil contains unsaturated fatty acids as does many yeast nutrient packages. There may be some scientific basis for the olive oil addition. I say give it a try.
I really surprises me that this olive oil idea has as much traction as it does. Grady Hull's thesis is scientifically flawed and inconclusive, the maltose falcon's experiments conclude that there really is no effect of olive oil, other than it only decreases head retention "a little bit", and the best we can get is a bunch of anonymous posters on the web forum that claim it has an effect when they use it.
Can't we put this one to bed? Leave the olive oil for cooking and if you want to oxygenate your wort, use a oxygen setup from your home brew shop.
Then what is with all the people who tried it with success. Just because you are uncomfortable doesn't mean you need to make up excuses to invalidate it. There is no scientific evidence that says it effects the beer and there are people who have tried it with success. Since when does science play bias?
I have seen only one credible experiment with olive oil on the homebrew level. The results were that the beer without olive oil was preferred by tasters. Even the company that originally did the research doesn't use it. What does that say?
Has anybody evaluated flavor stability over a long period of time?
Conducting a truly scientific experiment with OO would prove difficult because you are dealing with organic compounds that are subject to all kinds of variables. It is pretty clear that the amount of OO used doesn't cause significant effects on head retention. It is also pretty clear that for most Homebrewers, it probably isn't worth the risk or trouble.
Most tests I have read about don't use a control wort, so the results of fermentation may have just happened by natural causes. To be sure, one may have to run GC tests and have a significant amount of testing with controllable variables and some control methods. This is definitely something that a large brewery may want to consider, but I sure wouldn't want to risk my business model on a mostly untested methodology.
Fermentation is a very easy process to produce. Controlling every aspect of it can be tricky and never fail-safe. However, mother nature has pretty much got this down.
To me, it probably doesn't make enough difference to keep doing it. It kinda takes the "fun" out of brewing. Heck, I don't even inject O2 or even ambient air because I use a very strong starter. I see the current trend of using yeast nutrients as a potential oxygen reducing method. Servomyces (tm) is used frequently around the brewing world. I have yet to use it.
This all being said, I am planning a Oktoberfest brew very soon and I think I may take a few gallons out into another fermentation chamber and inject 1-2 mils of OO into it. Just to be safe, I will also just use the shake-method of injecting AA (Ambient Air).
If I do this, I for sure will come back with my results.
Brew Strong!
Any results yet?
Hi, I haven't done it yet... but I think I may try this on the next batch I have which would be a Heffeweisen I have ready to make. Since Heff is a lighter brew, I probably will go with a 1 mil infusion of OO. Now, let me tell you that 1 mil is next to nothing, in my book. I happen to have diabetic syringes all over the place as our cat is diabetic and he gets about 5. to 1 mil per day.
As a control, I will draw out 1 liter of wort into a separate container and ferment in the same environment to see what takes place naturally.
To make sure I get a good beer, I am going to do my usual routine of splashing the wort around out of the kettle into the fermentation stage.
I am still not sure how to quantify how this would work. I mean, how do you really determine yeast growth using this method? Duplicating the test would be a very challenging event in a home environment with so many variables.
I just can NOT believe that adding such a small portion would halt head retention. Last time I did this, there really was not a difference in the beer as far as taste, longevity, head retention... whatever.
The thread seems to strayed away from the primary goal of the paper. The reason for adding oleic acid (and avoid aeration) was to reduce oxidative effects in aging (hence the progressive experiments with longer warm stored beers) i.e. a more stable flavor profile.
Any tests evaluating the value of olive oil (oleic acid) additions to avoid aeration for the purpose of reducing oxidative effects in aging should evaluate the flavor profile at different ages under varying storage conditions. The discussion in this tread seems to be focused on whether or not the beer comes out tasting alright and retains its head, which while related, are not the primary point of the paper.
Has anybody evaluated flavor stability over a long period of time?
But you didn't have a control to check it against. It possibly/likely would have done the same thing without OO.
In this case (using oleic acid to increase yeast resistence/health in high ethanol environment) the research is already done (hence we don't really need to conduct our own research)
read "High-Gravity Brewing: Effects of Nutrition on Yeast Composition, Fermentative Ability, and Alcohol Production" in which oleic acid, ergosterol, and a nitrogenized source are used to supplement anaerobic and semi-anaerobic fermentations. While the paper finds success with this approach it also finds that consecutive aeration on days 1,2 and 3 with O2 can also achieve about the same results...
interesting quote from the paper for those planning to use oleic acid supplementation:
"Analysis of the levels of FAN before and after fermentation illustrates that in the presence of added lipids, usable nitrogen is, indeed, growth limiting and that the simultaneous presence of preformed lipids or oxygen is required for full utilization of such nitrogenous constituents"
Bottom line, use yeast extract (servomyces would work) along with oleic acid for proper results and if possible get an ergosterol supplement - however be careful it's hazmat!
Suggested amounts were .8% yeast extract (just use suggested servomyces amount), 24 ppm ergosterol and .24% (vol/vol) Tween 80 (their oleic acid source)
their test examples were repeatedly (repitched yeast) producing 16.2% alcohol in about 4 or 5 days of fermentation (anaerobically or semi-anaerobically) at 14 degrees celcius w/ lager yeast (in the 1980's - i.e. regular molson lager yeast)
"For the volume of wort we normally ferment, we would pitch about 4500L of yeast, and to that we would add around 300mL of olive oil.