Wort temperature gradient, top to bottom

[cire871]

Just brewed my 3rd extract brew a few days ago (Doppelbock). Was my 2nd time using the copper immersion chiller I made. During the post-boil chilling, I had a hard time getting the wort to a uniform temperature: the top layer of wort remained around 110-115 degrees while the middle and bottom were 60-70, after about 30 minutes. I eventually just poured my partial boil (2 gal) into my 60 degree top-off water (3 gal) and it was at pitching temperature immediately. I was trying not to stir the hot wort around to avoid HSA. The first time I used the immersion chiller, I stirred it around carelessly and ended up with a stale tasting beer (HSA is the only thing I can come up with for what went wrong, but I heard it can be pretty negligible). Should I just stir it next time and forget about HSA?

 

[stieg000]

Hot side aeration is not really a thing. The yeast are going to scavenge all the oxygen during fermentation. I've rocked the pot, stirred with my chiller, stirred with a spoon and now I just whirlpool till it's down to temp. Never noticed any staling.

It's probably somewhere else in your process after fermentation if your getting staling.

 

[cire871]

Hot side aeration is not really a thing. The yeast are going to scavenge all the oxygen during fermentation. I've rocked the pot, stirred with my chiller, stirred with a spoon and now I just whirlpool till it's down to temp. Never noticed any staling.

It's probably somewhere else in your process after fermentation if your getting staling.

Huh! So, why can't I just pour my partial boil into cold water? Won't I get a good cold break that way and be at pitching temperature almost instantly?

 

[micraftbeer]

When I was using a copper coil immersion chiller, it used to take me 30 - 45 minutes to chill a 5 gallon batch. I'd put the chiller in, put a lid on as best I could and cover up any gaps with aluminum foil for fear of wild elements getting in and turning my beer bad. I did that for several years.

Then I was doing a homebrew event at my local brewery, and the brewer was bouncing the coil up and down continuously. I asked him, and he said that otherwise it takes forever. I asked about the risk of wild infection coming in and he said he'd never experienced it. So I switched my method and it cut my time down to 15 minutes to chill, and I likewise never had any stray contamination. So I'd definitely recommend bouncing the coil up and down or stirring the wort.

As for "Why can't I just dump my hot wort in cool top off water and be done?", I think you exactly can do that. You just want to make sure you've got it figured right that you'll hit your temperature. It's easier to cool 2 gallons of hot wort than 5 gallons of warm wort.

 

[RPh_Guy]

Suggestions I've seen for cooling with an IC is that the kettle outside the top of the wort should no longer be hot to the touch. The rate of chilling slows down as the wort temp approaches your water temp.
For a partial boil I also have seen that you can add the hot wort directly to cold water with or without ice. Calculations are needed.
Cold break going into the fermentor is not a problem -- many people dump everything in or use counter-flow chillers or plate chillers which don't leave behind cold break.

Hot side aeration is not really a thing. The yeast are going to scavenge all the oxygen during fermentation....

Can you fix stale beer by adding yeast because they will "scavenge all the oxygen"? Why would beer with live yeast ever go stale?

Evidence/anecdotes for HSA-reduction (LODO) are stacking up showing it makes a noticeable improvement for avoiding staling. Compounds oxidize very rapidly when hot.
In my own experience I have also staled beer presumably by stirring during cooling.

 

[RM-MN]

Suggestions I've seen for cooling with an IC is that the kettle outside the top of the wort should no longer be hot to the touch. The rate of chilling slows down as the wort temp approaches your water temp.
For a partial boil I also have seen that you can add the hot wort directly to cold water with or without ice. Calculations are needed.
Cold break going into the fermentor is not a problem -- many people dump everything in or use counter-flow chillers or plate chillers which don't leave behind cold break.


Can you fix stale beer by adding yeast because they will "scavenge all the oxygen"? Why would beer with live yeast ever go stale?

Evidence/anecdotes for HSA-reduction (LODO) are stacking up showing it makes a noticeable improvement for avoiding staling. Compounds oxidize very rapidly when hot.
In my own experience I have also staled beer presumably by stirring during cooling.

Yeast scavenges oxygen when they are reproducing and fermenting. Once the sugars are gone they will no longer scavenge oxygen.

 

[RPh_Guy]

Yeast scavenges oxygen when they are reproducing and fermenting. Once the sugars are gone they will no longer scavenge oxygen.

Oxygen is a bull in a China shop.

You are talking about utilizing dissolved O2 (removing the bull). Yes the yeast removing the dissolved O2 slows future oxidative reactions.

The dissolved oxygen itself isn't the real problem (maybe the bull is sleeping). The problem is the chemical reaction between the dissolved oxygen and organic compounds in the wort/beer (the bull breaking all the China). The longer it's in there and the more agitated, the worst it gets.

Do yeast cause reduction reactions to repair or re-synthesize previously oxidized organic compounds in the beer (reversing staling - fixing the already broken China)? Nope.

Bottom line: yeast don't undo any oxidative damage already done on the hot side. Also, any attempt to imply that organic compounds (e.g. isohumulones) somehow can't become oxidized on the hot side is nonsense. Such reactions drastically increase with heat, occurring within seconds.

If you want more info there are some technical articles/guides out there on HSA and LODO that explain it better than I have.

 

[micraftbeer]

... Also, any attempt to imply that organic compounds (e.g. isohumulones) somehow can't become oxidized on the hot side is nonsense. ...

I've seen it happen before.

Does that statement count as an implication? Sorry, couldn't help myself... Ha!

 

[RPh_Guy]

 

[cire871]

Thanks everyone! I'll probably just slowly stir it or move the chiller up and down next time.

 

[Horseflesh]

I recommend getting some assistance because stirring is a real drag. A pump is great, but it's one more thing to clean. A variable speed drill with a wine degasser still means you have to stand there, but it's a lot less work than using a spoon. Definitely do something though, as you found it takes forever without moving the wort around.

However you do it, if you want to be careful about possible HSA, just don't splash.