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Avoiding Oxidizing Wort

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I'm going for my third attempt at brewing this weekend. The first two were "drinkable" however, I couldn't help but notice a cardboard like off taste in my beers. I'm thinking this is because I had too much oxygen in my wort. The things I did compared to the things I'm changing:

org. vs. trying
3 gal wort ---- 4 gal and boiling/cooling final gal to add
poured wort in fermenter ----- siphoning cooled wort into fermenter
strong stirring to cool ----- slow controlled stirring

Am I missing something else that may decrease my change of oxidizing?
Thanks for the help!!
 

brewmasterpa

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you want to oxidize your wart prior to pitching your yeast. the yeast have to have plenty of oxygen to do their thing. you might be oxidizing it after fermentation without knowing it. you have to be extra careful when bottling to avoid this, use a bottling wand and make sure theres no bubbles in your bottle when youre filling. if youre kegging, purge the air out by pressurizing your keg to 30psi, then purge, then pressure, then purge 3 times before you cool and carbonate. after fermentation, do not shake, stir, or bubble your beer any way at all. oxygen introduced into the wort is your friend, after fermentation is your enemy.
 

malkore

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Well prior to fermentation starting, its oxygenating the wort...not oxidizing.

just make sure its cooled below 90F before oxygenating, to avoid any possible risk, no matter how slim, of hot side aeration creating oxidized beer.
 

SumnerH

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Well prior to fermentation starting, its oxygenating the wort...not oxidizing.

just make sure its cooled below 90F before oxygenating, to avoid any possible risk, no matter how slim, of hot side aeration creating oxidized beer.
But realistically hot side aeration is somewhere between wildly overexaggerated and total myth, depending on who you believe. It's not something that's going to consistently affect multiple batches with anything less than total lack of care during cooling.

More likely you're introducing oxygen at a later stage--are you using a secondary? If so, are you being careful to do a splash-free siphon when transferring to the secondary? Are you racking to the bottling bucket or bottling in a more-vigorous-than-usual manner? Are you taking a ton of gravity readings (5+) or otherwise introducing O2 into your fermentors?
 

dontman

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The most important question to ask here is: how long after bottling are we talking here? I have never heard of a beginner's beer getting old enough for oxidation to become apparent. This takes a minimum of 3 months before any cardboard flavors would start to become noticeable. Seriously, if you have been patient enough for this to occur I commend you.

And on Hot Side Aeration, to be clear it is fear of HSA occurring preboil that is overblown. If you are aerating post boil, before the wort is cool, i.e. between 212 and 90 degrees, then you will easily see oxidation qualities in your beer as it ages. At those temps the oxygen will bond with the wort molecules in a way that the yeast cannot shake loose. (Rolling boils will break most of this bonding which is why preboil HSA is largely myth.)

Again though, this deterioration only becomes apparent as the beer gets old.

The point is, if you think you are tasting cardboard but the beer has only been in bottle for a short period of time I would wager that you are mistaking another off flavor for oxidation. My guess would be either green beer flavors or extract twang.
 

FireBrewer

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(Rolling boils will break most of this bonding which is why preboil HSA is largely myth.)
Not true. Once oxygen binds, it will not break loose in the boil. Boiling removes only unbound oxygen. (source: Principles of Brewing Science, Fix)

HSA isn't a myth but it is VERY difficult to produce on a homebrew scale. Also, how can you differentiate oxidation produced preboil (albeit unlikely) and oxidation post-fermentation?

The point is, if you think you are tasting cardboard but the beer has only been in bottle for a short period of time I would wager that you are mistaking another off flavor for oxidation.
Agreed.
 

brewmasterpa

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ok, so that was a lot of very specific stuff that this poor guy wasnt expecting. let me summarize. after the boil, dont oxygenate until the wort is chilled. once its chilled, oxygenate the hell out of it before pitching yeast. after fermentation, do not oxygenate. no bubbles, no splashing, no stirring, no shaking, nothing. there you go.
 
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Thanks for all your help. I have a great feeling about this batch.
 
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