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amrmedic · 03-01-2011, 02:22 PM

A friend showed me this article. It basically says you dont need to aerate the wort by using a drop of olive oil. Has anyone heard of this?

I tried it in my starter and the starter went nuts, so it may be true. I have not tried it in a full batch yet.

www.brewcrazy.com/hull-olive-oil-thesis.pdf

ArcaneXor · 03-01-2011, 02:39 PM

It does seem to work. I have used it off and on to supplement manual aeration, but right now I have an IPA in the fermentor that uses just olive oil; no manual aeration whatsoever. I am very interested to see how it'll turn out! If it works well, I plan on switching to it permanently.

broadbill · 03-01-2011, 03:35 PM

Its been discussed (try a search)....there are some significant flaws in the work, but then you also have a bunch of ancedotal evidence from homebrewers (such as ArcaneXor) who say its for real.

If you look at the thesis in the link you posted, the big flaw (at least that I saw) is that they don't have a control sample that was not aerated at all to compare to the samples oxygenated by either stone or by olive oil. Their rationale for this was that if olive oil did not have an effect on fermentation, then you would expect to see a decrease in yeast/fermentation measures. In other words, a lack of a response is their evidence that it olive oil works.

Sure enough, their data shows is no difference between oxygenation with a stone and olive oil addition, which they interpret to mean that olive oil is just as effective as an oxygen stone in promoting yeast growth and fermentation.

What this experiment assumes is that oxygenation is an effective promoter of yeast growth/fermentation in the first place! However, It is is entirely possible that oxygenation (by whatever means) it has no effect in this scenario, right? Therefore, you can really say conclusively that olive oil is good at oxygenating wort as measured by fermentation output, when its unclear if oxygenation (by whatever means) is good at stimulating fermentation. This is where the no-oxygenation control comes in....to first show that you need good oxygenation...and then you can conclusively say if olive oil is any better/worse than the stone at oxygenating wort.

PS...before people start throwing more anecdotal data my way, I have some of my own: This study was fermenting a 1.057 wort and testing oxygenation with either a stone or olive oil. I've fermented many of 1.057-60 wort without any oxygenation and they've all fully attenuated and fermented cleanly. This (albeit anecdotal!) evidence suggests that you don't need to oxygenate 1.057 wort for adequate fermentation.

**IrregularPulse** · 03-01-2011, 03:37 PM

comes up every few months

GaryJohn · 03-01-2011, 03:39 PM

I've heard of this as well, but I heard the amount of olive oil you'd need for a homebrew batch is like less than 1 drop. I'm a little skeptical...so please report back with your results! How much oil did you add?

rycov · 03-01-2011, 03:46 PM

anyone ever go with no aeration? just curious because water already has oxygen in it right? (not just the H2O part i mean extra) not sure what happens when you boil it though. seems like if you just shake it up the bubbles come out of solution pretty quick anyway.

broadbill · 03-01-2011, 03:47 PM

Quote:

Originally Posted by rycov

anyone ever go with no aeration? just curious because water already has oxygen in it right? (not just the H2O part i mean extra) not sure what happens when you boil it though. seems like if you just shake it up the bubbles come out of solution pretty quick anyway.

Boiling causes the oxygen to come out of solution, which is the rationale for oxygenation/aeration. You need some oxygen in solution for proper yeast cell membrane growth...or so the theory goes...

**GilaMinumBeer** · 03-01-2011, 03:49 PM

Yes but it only works on Italian beers.

Olive Oil is touted as being the highest in Linoleic Acid next to just straight Linoleic Acid.

remilard · 03-01-2011, 03:54 PM

Quote:

Originally Posted by broadbill

Its been discussed (try a search)....there are some significant flaws in the work, but then you also have a bunch of ancedotal evidence from homebrewers (such as ArcaneXor) who say its for real.

If you look at the thesis in the link you posted, the big flaw (at least that I saw) is that they don't have a control sample that was not aerated at all to compare to the samples oxygenated by either stone or by olive oil. Their rationale for this was that if olive oil did not have an effect on fermentation, then you would expect to see a decrease in yeast/fermentation measures. In other words, a lack of a response is their evidence that it olive oil works.

Sure enough, their data shows is no difference between oxygenation with a stone and olive oil addition, which they interpret to mean that olive oil is just as effective as an oxygen stone in promoting yeast growth and fermentation.

What this experiment assumes is that oxygenation is an effective promoter of yeast growth/fermentation in the first place! However, It is is entirely possible that oxygenation (by whatever means) it has no effect in this scenario, right? Therefore, you can really say conclusively that olive oil is good at oxygenating wort as measured by fermentation output, when its unclear if oxygenation (by whatever means) is good at stimulating fermentation. This is where the no-oxygenation control comes in....to first show that you need good oxygenation...and then you can conclusively say if olive oil is any better/worse than the stone at oxygenating wort.

PS...before people start throwing more anecdotal data my way, I have some of my own: This study was fermenting a 1.057 wort and testing oxygenation with either a stone or olive oil. I've fermented many of 1.057-60 wort without any oxygenation and they've all fully attenuated and fermented cleanly. This (albeit anecdotal!) evidence suggests that you don't need to oxygenate 1.057 wort for adequate fermentation.

You are too hung up on terminal gravity as the metric of success. We aren't making industrial ethanol here. That aeration affects the flavor of beer is heavily tested and known and the New Belgium experiment shows that olive oil and aeration produce different flavor profiles as confirmed by gas chromatograph and tasting panel.

twigboy2000 · 03-01-2011, 03:56 PM

I almost never aerate or oxygenate my wort before pitching yeast. I always use a stirplate starter of the correct size recommended by MrMalty. It's my understanding that Oxygen is required for the growth phase of the yeast which has already been accomplished by the stirplate.

The only beer that has had an attenuation problem was a large belgian quad that I underpitched.

-chuck