Commercial brewing: why feeding the grist to mash vessel from the top is a "problem"?

[Finlandbrews]

I'm reading from the Institute of Brewing and Distilling Brewing course that feeding the Mash conversion vessel from the top is less used because there is more oxygen pick up. Why is oxygen pick up a problem for the mashing/conversion stage?

 

[Contrarian]

Hot side aeration (HSA) is heavily controlled by commercial breweries. There isn't clear consensus on hobby scale but chemically it does make sense.

Theses are the precursor molecules to the staling reaction.

 

[madscientist451]

I've been to lots of small breweries and they all feed the mash tun from the top. The water is piped in and the grain is generally introduced at the same time.

On the home brew level, a Brulosophy experiment was done on the subject of hot side aeration:
http://brulosophy.com/2014/11/18/is-hot-side-aeration-fact-or-fiction-exbeeriment-results/

 

[Finlandbrews]

Hot side aeration (HSA) is heavily controlled by commercial breweries. There isn't clear consensus on hobby scale but chemically it does make sense.

Theses are the precursor molecules to the staling reaction.

But oxygen is boiled away at boiling so my question is why can oxygen cause problems at mashing?

 

[dcbw]

Possibly because it (debatably) can oxidize the mash liquor. Look up the threads on Low Dissolved Oxygen (LODO) brewing in the Brew Science topic. Those people swear they get "maltier" beer and that the hop flavor fades less quickly. Part of that process is to de-oxygenate the strike water and to ensure the mash doesn't get oxygen in it by not stirring very hard.

Nobody's done a dissolved oxygen or triangle test from the LODO methods though, so who knows if it's actually a thing or not.

 

[oujens]

Yeah, I'm not taking sides but the LoDO method does have some interesting points. Especially when you compare the method to the one used in the brulosophy experiment. Based on the paper, the brulosophy experiment was flawed because both mashes contained high amounts of dissolved oxygen which was present in the strike water. The damage would have been done to both so no difference in flavor. Based on cited work in the paper, oxygen can cause damage rather quickly. Interesting thoughts for sure. I'm going to give it a try in the coming months on lagers.

 

[brewcat]

I've been to lots of small breweries and they all feed the mash tun from the top. The water is piped in and the grain is generally introduced at the same time.

On the home brew level, a Brulosophy experiment was done on the subject of hot side aeration:
http://brulosophy.com/2014/11/18/is-hot-side-aeration-fact-or-fiction-exbeeriment-results/

My biggest problem with that one is they didn't age the beers at all. The main reason to control oxygen is for longer storage. I personally had a dubbel become oxidized after a couple months that I've attributed to HSA because of splashing during cooling.

I try to control things within reason. Stir the mash lightly. No splashing when chilling until the temp is less than 80.