Is there any Oxidation risk before the boil?

I have been homebrewing for only 6 months but have researched more than most 5 year brewers and consider myself a well educated newbie!

I'm well aware of the oxidation risks post boil, when racking and while bottling but last night I was thinking about my AG full boil I'll be doing this weekend and wondered if there is any oxidation risk BEFORE the boil?

Lets say you collect your wort in a 6 gallon bucket from the mash tun and then pour it into your brew pot...is this an oxidation risk? I personally don't see how anything you do pre-boil could hurt as the boil will take all the oxygen back out but please tell me I'm wrong if that's the case.

Happy brewing!

 

No risk. You're adding oxygen back in after the boil for aeration...so prior to fermenting, o2 is a good thing.

 

^ Thanks. I did a search and saw someone quoting Palmer that stirring too hard during the boil could cause oxidation and that made no sense to me but got me questioning my thinking.

Is there an oxidation risk while the wort is cooling down from boiling to pitching temps. I have always been careful not to stir too hard while my wort is chilling, does it matter?

 

No, in fact, there are kits to add oxygen to the wort before pitching.. or simply putting an aquarium stone in the wort and attaching to a fish tank pump (takes much longer though)

It's only after you pitch the yeast that it's a problem. Vigorous stirring is not an issue.. but the longer you leave the wort exposed.. the more chance of getting floating bacteria in the wort.

I oxygenate and pitch the yeast as soon as possible once cooled

 

The cool thing about homebrewing is your learn something every day!

 

Only if you believe in hot side aeration.

 

So there is a debate over the existence of such?

 

The quote may have been talking about hot side aeration, which most people on here will tell you is a myth, the quote could be old too. I generally try and avoid it, but dont obsess about it. But like everyone has said oxygen before fermentation is good, yeast need it.

 

The boiling drives out oxygen anyway...

 

Yes. There have been studies of this especially before the boil. The temp. range before boiling esp. The mash and lautering are low enough that oxygen can dissolve in the liquid and cause oxidation.on the other hand boiling wort and wort right after boiling is so hot that very little oxygen can be dissolved in it. This is just all been recited from byo magazine. I am not totally sold on this theory.

Edit: old article

 

The other thing that I just read recently from Designing Great Beers is that oxygen introduced pre-boil can have a (very) small effect on the color of the beer. I don't have a quote for you, but it had to do with the oxygen interacting with some of the byproducts of the mash and enzymes and can cause the beer to become slightly darker. (We're talking ~0.5L*). I know it doesn't really mean much, just wanted to add my $0.02 and make myself feel a little bit smarter by sharing from what I was reading.
But I too have not really been overly worried about slight splashing while mixing the mash or wort. I just try to stir without purposefully splashing.