OG reading change up

[Brewer #89247]

So for years I've always taken my post-boil OG reading from the fermenter (before pitching) or from the kettle once cooled. Recently I've been having some crazy up and down readings differing between my refractometer and (2) hydrometers and I partially concluded that I wasn't getting a solid "mixed" sampling if you will. Today I chose to take my reading about 55 min into my 60 min boil for two reasons. 1.) It should be mixed extremely well due to the kinetic rolling of the boil 2.) If I'm under my target OG, I can continue to boil a little longer and not risk missing my target. I cooled the small sample quickly. Good news, it was dead nuts for my efficiency. Weird news, I took a few readings once cooled and got some really erratic numbers again. (Yes, everything is calibrated, tested, etc.) I'm assuming it had to do, once again, from "where" I was pulling my samples. Does anyone else use this technique? I'm guessing yes, but didn't think it could hurt to ask. Cheers to a hybrid WC/NE IPA I knocked out today, can't wait to see how she turns out.

 

[thunderwagn]

I almost always take my sample out of the brew kettle during the last couple minutes of the boil. Main reason? Just because I use a glass measuring cup to pull the sample and at a boil it doesn't matter much if it's sanitized or not. That said, this reminds me of when people use like 3 different thermometers, or several different recipe editors, 2 different yeast calculators and always wonder why they get different for each. I gave up on all the hassle and hair splitting/pulling long ago and go with one. Makes life simpler and my beer still comes out just fine.
I guess it never hurts to compare. Especially if you think you have a problem, but imo, generally speaking all the comparisons just aren't necessary. Pick your favorite or the one you feel is most fitting and roll with it.

 

[J A]

Pre boil gravity sampling has been pretty useless for me. And I haven't really had much luck getting meaningful refractometer readings. I know my system well enough to be within a reasonable margin of error with efficiency. I'm not far enough off at pre-boil to throw off hop uptake. When I over boil a little, I'll top up a touch if it's important to style. If gravity is a little lower than I expected, I'll drink beer that's a half a point lower in alcohol.

 

[GFHomebrew]

I recon main thing is getting consistent outcomes from one mash to the next. X amount of grain using my system yeilds this many gravity points - so when calculating recipie you know your going to have a predictable outcome in the beer you brew.

 

[Ozarks Mountain Brewery]

the main issue with readings is the wort just isn't mixed up well enough to get an accurate reading most of the time and we don't want to stir rapidly and introduce too much oxygen

 

[J A]

we don't want to stir rapidly and introduce too much oxygen

Thead drift alert...
Isn't one of the purposes of boiling fairly vigorously to drive off oxygen? If we have to work so hard to introduce oxygen into the wort solution after it's cooled, there's not much that could gotten through the boil. And if it did, doesn't it get used up during fermentation with all the rest of the oxygen we put in during aeration?

 

[Ozarks Mountain Brewery]

too much oxygen in the wort can have negative effects in the taste, you can’t rely on boiling all oxygen out and if its introduced to the mash and fused with it, it’s a bad thing, when we add oxygen for the yeast it sits on the outside not fused with the molecules. Now stirring isn’t going to create this but let’s say a blender type of stir is and I’m talking before the boil not after

 

[J A]

Yeah...that make sense. I can't imagine that stirring could introduce more O2 than recirculating does and no one seems to think that's an issue.