Can mash technique have a major impact on final gravity?

[bacchusmj]

I've been doing all grain batches for about two years. I batch sparge. Over those two years I have often struggled to hit my fgs. Usually beers crap out around 1.02.

I've been taking notes on technique and I've found that I've switched up my batch sparge technique fairly often. Usually I mash, mash out with boiling water and then refill at 170 to drain once for my final gravity. This has been about 50/50 on hitting fg.

Last week I brewed a big red at 1.079. Instead of one sparge I split the sparge into two, then had to do a third to get my volume for a 90 min boil. This one finished perfect.

Question: should sparge technique have this dramatic an effect on fg, or was it just good process? I always assumed fg was about temps, aeration, yeast, ferm temp? Could it be my mash process?


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[billl]

Can it? Sure.....if you are continuing to hold it at mash temps. As long as it is at mash temps, enzymes will continue to work. If you raise the temp to 170, you'll denature the enzymes and anything after that will have no impact on the fermentability of the wort.

If you continually are finishing high on FG and aren't knowingly mashing at higher temps, you should calibrate your thermometer. A few degrees off could keep your beer from drying out to the level you want.

 

[BigFloyd]

What kind of thermometer are you using to measure mash temp? The floaters are notoriously inaccurate. My first one was a whopping +7*F off.

 

[bacchusmj]

I've got a Digital instant read that I regularly compare to my blichmann thermometer and I calibrate every brew day in crushed ice. I'm pretty sure it's not temps.


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[day_trippr]

Three things:

-They are asking about your mash temps

- Calibration for a mash thermometer is probably better done at boiling temp than freezing

- I would not use a Blichmann thermometer as a calibration reference...

Cheers!

 

[billl]

" I'm pretty sure it's not temps." Temps and time are the only things in the mash that will drive attenuation numbers. What temp do you think you are mashing at? How long?

Just to clarify, you can't calibrate in crushed ice. You need ice water and it should be as pure as possible.

Other than that
a) how do you determine how much yeast to pitch?
b) how and how long do you aerate?
c) how do you control fermentation temps?