[ccarlson]

Can't wait 'til this turns into the "Olive Oil Discussion."
Just stirring the pot...

Not trying to start that discussion, but did anyone ever prove that olive oil works?

[tubercle]

Can't wait 'til this turns into the "Olive Oil Discussion."
Just stirring the pot...

Not trying to start that discussion, but did anyone ever prove that olive oil works?

Weazletoe swears by it.

[gordonstrong]

Can't wait 'til this turns into the "Olive Oil Discussion."
Just stirring the pot...

Not trying to start that discussion, but did anyone ever prove that olive oil works?

With red wine vinegar, it makes a nice salad dressing.

[bluesman]

Can't wait 'til this turns into the "Olive Oil Discussion."
Just stirring the pot...

Not trying to start that discussion, but did anyone ever prove that olive oil works?

With red wine vinegar, it makes a nice salad dressing.

Balsamic as well. 

[johnf]

Can't wait 'til this turns into the "Olive Oil Discussion."
Just stirring the pot...

Not trying to start that discussion, but did anyone ever prove that olive oil works?

It is immediately obvious that it provides oleic acid to yeast.

In the Grady Hull paper, from which this whole craze was lifted, no amount of olive oil produced a beer with esters as low as or lower than the control beer (normal oxygenation) as measured by gas chromatography and tasting panel. So one might suspect that providing oxygen to yeast is doing something other than just provide oleic acid, or possibly that olive oil is delivering compounds other than oleic acid which are somehow causing the elevated esters. Somehow isolating oleic acid and delivery that in pure form would answer the question but I would bet a case of Cantillon that it is the former, supplying oxygen to yeast is materially different than supplying them with oleic acid.

Notably the brewery where the research was conducted, New Belgium, did not adopt the practice. AFAIK no commercial brewery has ever done this in production.

So I guess you have to define "works". Can it make a beer identical to a beer made with normal practices? No. Can it make an acceptable beer? Yes. Can it make a better beer than normal practices? Beauty is in the eye of the beholder.

[johnf]

I don't think that is much of a problem. I think shearing forces (from stirring the mash) are more of a concern. Commercial systems are designed to stir low-shear, for good reason. I have seen few homebrew designs that are likely to be a big problem.

Shearing?  Are you talking about someone whipping the mash vigorously?  I do try not to get much cavitation when I stir the mash.

Yes. I doubt that would occur in homebrewing, though I think back in the day automated mash stirring was used by some homebrewers. I think that homebrewers these days have almost uniformly adopted recirculation of the liquid rather than stirring, if they automate.

You can imaging that in a commercial mash-tun the different between a naively designed stirring mechanism and one designed to be low shear could be quite large.

[tom]

I would bet a case of Cantillon

just shared my last bottle last night

[denny]

AKA HSA (Hot Side Aireation) = Debunked Myth.

I wouldn't go quite that far, but I do think it's not the problem it's been made out to be in the past.

 I guess that is a little too far

 I guess I should have said that its not as big of a problem that it is made out to be.

 Its certainly not on my list.

My approach is to just remember it may be a possibility and try to avoid it, but not go crazy worrying about it.

[gymrat]

I think that is a very sensible approach?

So tell me about this olive oil thing 

[Will's Swill]

For the OP, I'd get a hose or at least situate the kettle so the liquid draining out contacts the side rather than falling all the way to the bottom and whipping things up more.

Wouldn't this be worse?  I would think that spreading the flow in a thin layer on the side of the kettle would aerate more than just letting it drop to the bottom.

[denny]

So tell me about this olive oil thing 

Fie on you!

[jlap]

A friend of mine has a HERMS horizontal brew system with 2 pumps that produced a string of oddly but intensely oxidized beers.  It turned out that the pumps were oriented such that they were cavitating a lot during recirculation.  The problem was worse with darker beers.  Changing the orientation of the pumps fixed the problem ASFAIK.  That's the only example of HSA that I've ever tasted at club meetings.

[mabrungard]

A friend of mine has a HERMS horizontal brew system with 2 pumps that produced a string of oddly but intensely oxidized beers.  It turned out that the pumps were oriented such that they were cavitating a lot during recirculation.  The problem was worse with darker beers.  Changing the orientation of the pumps fixed the problem ASFAIK.  That's the only example of HSA that I've ever tasted at club meetings.

Cavitation cannot create oxidation.  The bubbles are products of the intense vacuum created by the pump at cavitation condition.   There would have to be a leak that allows an external air source into the flow loop for the bubbles to create the oxidation effects.

[ccarlson]

A friend of mine has a HERMS horizontal brew system with 2 pumps that produced a string of oddly but intensely oxidized beers.  It turned out that the pumps were oriented such that they were cavitating a lot during recirculation.  The problem was worse with darker beers.  Changing the orientation of the pumps fixed the problem ASFAIK.  That's the only example of HSA that I've ever tasted at club meetings.

Cavitation cannot create oxidation.  The bubbles are products of the intense vacuum created by the pump at cavitation condition.   There would have to be a leak that allows an external air source into the flow loop for the bubbles to create the oxidation effects.

For the most part, I agree. However. could there be other factors at play here?

[jlap]

I think leaks were part of the problem too but I'd have to double check.