Can some one explain this.

[i4ourgot]

I was reading the Northern Brewer web site on off flavors. And under Cardboard/ Oxidation it says that aerating hot wort can be the cause. Is this during the boil they are talking about or while its chilling?

http://www.northernbrewer.com/connect/2011/08/common-off-flavors/

 

[BrewKnurd]

I imagine they're referring to either. The idea behind hot side aeration is that getting unnecessary oxygen into the wort at elevated temperatures causes some oxidation reactions, the products of which then carry over into the fermenter and the finished product. Some people think it's a big problem. Some people think its a myth. I personally go with the opinion of Dr. Charlie Bamforth, who is way more knowledgeable than I am in the brewing sciences. His basic assessment was that it is not a myth, it can indeed happen, but that for homebrewers, they are vastly more likely to cause themselves problems in packaging with regards to oxidation than they are to have issues due to HSA. That said, there's no reason to unnecessarily introduce oxygen while the wort is hot.

 

[billl]

The theory is that you can oxidize various compounds in the wort by exposing to high temps and O2. O2 is driven off during the boil, so it would only be under none boiling conditions.

On a practical level, I've never heard of anyone who has actually had hot side aerating issues. It might be a concern at commercial breweries where they are heating and cooling hundreds or thousands of gallons, but I doubt it. Most of them whirlpool the wort for extended periods at off boiling temps to remove trub, hops etc or even to add hop flavor at that point. That is putting way more O2 into the beer for a longer period of time than you are likely to even do on a homebrew scale.

 

[cluckk]

They are talking about splashing hot wort. During the boil you are actually driving off oxygen. That is why you aerate before pitching. Until it is cooled be careful about how much you agitate the wort.

 

[i4ourgot]

what would you say is cooled as far as temps go for wort. I don't have a stone so I whisk my wort this also seems to help cool my wort quicker.

 

[Xpertskir]

HSA is nonsense. The only time you need to worry about not adding O2 to your beer is post ferm. RDWHAHB and do whatever you want O2 related until after the beer has been fermented. More to the point do whatever you want until the yeast is done replicating(you see any krausen).