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Old 03-01-2011, 03:59 PM   #11
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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?
The New Belgium study used 4 different amounts, you can read it in there.

The amount for 5 gallons would be challenging to measure. I would personally make an olive oil water emulsion (but what emulsifying agent to use? lecithin? maybe star san?) with whatever amount of oil I could measure with a reasonably priced pipette and then add a small amount of the emulsion.
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Old 03-01-2011, 04:30 PM   #12
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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.
Actually, I'm more hung up on the design of the experiment, and if oxygenation is even required in the first place. I was using terminal gravity/FG to illustrate my criticism, but it holds true for all of the other metrics and were not different between olive oil and traditional aeration.

As for the different ester profile: Differences were only detected in the super-sensitive GC experiments and not in the sensory panels. How significant are those differences in ester profiles then?
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Old 03-01-2011, 04:32 PM   #13
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Actually, I'm more hung up on the design of the experiment, and if oxygenation is even required in the first place. I was using terminal gravity/FG to illustrate my criticism, but it holds true for all of the other metrics and were not different between olive oil and traditional aeration.

As for the different ester profile: Differences were only detected in the super-sensitive GC experiments and not in the sensory panels. How significant are those differences in ester profiles then?
Read the study more carefully, the tasting panel reported the increased esters in all 4 tests.

As for whether or not oxygen at the onset of fermentation affects beer flavor I don't know what to tell you other than that there is a mountain of literature that you are apparently intentionally ignoring.
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Old 03-01-2011, 04:33 PM   #14
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Differences were only detected in the super-sensitive GC experiments and not in the sensory panels.
Yeah Remilard! Since when does "sensory analysis" have anything to do with taste?
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Old 03-01-2011, 04:36 PM   #15
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I saw the same issue Bill mentioned in the study. But it is widely accepted that wort needs aeration in order for healthy yeast to bud and propagate. There are a multitude of factors that goes into healthy yeast and fermentation. Also, the levels of various nutrients in the wort, temperature and even the strain of yeast being used.

A basic way of testing this at home is simple. Brew a 5 gallon batch of beer. Split the wort into 5 1 gallon fermenters (same style) and using the same pack of yeast, pitch the yeast (hard part, ensuring each batch has the same quantity of yeast to start) and place into a controlled temp fermentation chamber. In 1 use olive oil, in the other aerate with oxygen and an aeration stone, in another aearate by shaking/stirring, in another no aeration and the final one use straight lineolic acid. Ensure each batch has the same starting SG before pitching. Then each day measure the SG of each batch. Then graph it out.

This is by no means a hard and fast study as there will be issues, but it can give you a ballpark idea of the different methods. And at the end of the experiment, combine all 5 batches into a keg, carb it and then drink the experiment.

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Old 03-01-2011, 04:41 PM   #16
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I saw the same issue Bill mentioned in the study. But it is widely accepted that wort needs aeration in order for healthy yeast to bud and propagate. There are a multitude of factors that goes into healthy yeast and fermentation. Also, the levels of various nutrients in the wort, temperature and even the strain of yeast being used.

A basic way of testing this at home is simple. Brew a 5 gallon batch of beer. Split the wort into 5 1 gallon fermenters (same style) and using the same pack of yeast, pitch the yeast (hard part, ensuring each batch has the same quantity of yeast to start) and place into a controlled temp fermentation chamber. In 1 use olive oil, in the other aerate with oxygen and an aeration stone, in another aearate by shaking/stirring, in another no aeration and the final one use straight lineolic acid. Ensure each batch has the same starting SG before pitching. Then each day measure the SG of each batch. Then graph it out.

This is by no means a hard and fast study as there will be issues, but it can give you a ballpark idea of the different methods. And at the end of the experiment, combine all 5 batches into a keg, carb it and then drink the experiment.
I would hope that anybody criticizing the methods used to produce the paper in the OP would not seriously propose that a casual test with no trained tasting panel and statistical analysis is acceptable.
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Old 03-01-2011, 05:13 PM   #17
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Read the study more carefully, the tasting panel reported the increased esters in all 4 tests.

As for whether or not oxygen at the onset of fermentation affects beer flavor I don't know what to tell you other than that there is a mountain of literature that you are apparently intentionally ignoring.

I did read it and I'll rephrase...the sensory panel could not consistently taste flavor difference in between the two samples.

The results are all over the place:

In trial 1: GC showed significantly different levels of isolamyl acetate and ethyl hexanoate, yet there no significant differences in the sensory panel for these compounds. Just that they could "taste differences" in ester and they preferred the olive oil treated beer.

In trial 2: GC showed that levels of ethyl hexoanoate were not significantly different, yet the sensory panel was somehow able to pick up a significantly different level of ethyl hexoanoate??

As for the isoamyl acetate, levels were high in GC, but yet again the sensory panel missed it.

Trial 3: actually consistent, lower esters by GC, no difference by sensory

Trial 4: also somewhat consistent...high ethyl hexoanoate, also found in the sensory.

I wonder if the sensory panel started to get biased, they did state the preferred the olive oil beer and could probably taste it. Also, it doesn't sound like they were doing triangle tasting tests, either.

Be that as it may, my point still stands that the study wasn't designed like it should...
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Old 03-01-2011, 05:17 PM   #18
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I would hope that anybody criticizing the methods used to produce the paper in the OP would not seriously propose that a casual test with no trained tasting panel and statistical analysis is acceptable.
No, it wouldn't be acceptable...just like it isn't acceptable to leave out a negative control.
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