Originally Posted by Captain Damage
Dr Charles Bamforth has pretty well exposed HSA as a myth. He talks about it in one of his BrewStrong interviews, and mentions that some major commercial brewers actually deliberately bubble air thru hot/warm wort.
I just Googled it and I found the podcast. This is what it says in the description:
"Dr Bamforth explains some of the myths and legends surrounding the controversial topic and instructs brewers on how to deal with HSA based on his own extensive research"
It says he explains some of the myths, not that it's all a myth. I honestly don't have the time right now to listen to it but all I'll say is there are dozens of articles about it. If he says it's all a myth then I wonder why the whole brewing community hasn't accepted and adjusted to it and why books still teach the same thing. Not saying I don't believe it, just that every time we turn around someone else is stating something is a myth due to their experimenting. When I get a moment I'll give that podcast a listen.
*EDIT - This is from Palmer's book and is still in the latest edition albeit written a little more thoroughly in the book:
"You should not aerate when the wort is hot, or even warm. Aeration of hot wort will cause the oxygen to chemically bind to various wort compounds. Over time, these compounds will break down, freeing atomic oxygen back into the beer where it can oxidize the alcohols and hop compounds producing off-flavors and aromas like wet cardboard or sherry-like flavors. The generally accepted temperature cutoff for preventing hot wort oxidation is 80°F.
Oxidation of your wort can happen in several ways. The first is by splashing or aerating the wort while it is hot. Other beginning-brewing books advocate pouring the hot wort after the boil into cold water in the fermenter to cool it and add oxygen for the yeast. Unfortunately the wort may still be hot enough to oxidize when it picks up oxygen from the splashing. Pouring it down the side of the bucket to minimize splashing doesn't really help either since this increases the surface area of the wort exposed to the air. Thus it is important to cool the wort rapidly to below 80°F to prevent oxidation
, and then aerate it to provide the dissolved oxygen that the yeast need. Cooling rapidly between 90 and 140°F is important because this temperature region is ideal for bacterial growth to establish itself in the wort."
Again, I'd like to know why it's a myth when it's still claimed today supposedly using science as a result - in this example the oxygen binding chemically to certain compounds and later breaking down into the beer.