Does Mash Temp Matter?

[frazier]

Yes, I know the answer is 'yes'. But the results of my two most recent all-grain batches have me confused.

Batch #1: Mash temp 157. OG = 1.056. Yeast = WLP011. FG = 1.014

Batch #2: Mash temp 152. OG = 1.054. Yeast = S-05. FG = 1.014.

So, by the numbers, I got better attenuation from the higher mash temp and less attenuative yeast. Clearly, mash temp doesn't matter!

 

[Bobby_M]

Same grain bill?

 

[frazier]

No, I used Golden Promise as the base malt in #1, and American 2-row in #2. This was not a scientific variable-controlled experiment; just an unexpected result using reasonably standard techniques.

 

[WoodlandBrew]

Agreed. There are too many variables (by using different base malts and different yeasts) to draw a conclusion from your experiment. Wyeast and Kai have done some very controlled experiments on this. The results are summarized here:

http://woodlandbrew.blogspot.com/2013/01/measured-mash-temperature-effects.html

 

[MarcusKillion]

I think it may matter in the body and perhaps flavor of your beer and ABV. too me it does not matter much as I am not that technical about brewing . I usually keep mine from 148 to 153 .

 

[frazier]

Agreed. There are too many variables (by using different base malts and different yeasts) to draw a conclusion from your experiment. Wyeast and Kai have done some very controlled experiments on this. The results are summarized here:

http://woodlandbrew.blogspot.com/2013/01/measured-mash-temperature-effects.html

Interesting! Thanks for that link. So it seems that my results were more or less within the "error bars" in my "Laboratory conditions". So while the results were unexpected, they were not wildly out of bounds.

I guess next time I brew that Scottish Ale, I'll mash closer to 160*.

 

[Beernik]

It's definitely an impossible conclusion to draw since different yeasts were used by the OP. Different yeasts have different attenuation ranges.

I did an amber ale & a sweet stout on successive days and fermented them side-by-side. Both used Wyeast 1318 - London Ale III.

Amber Ale: mash 149F, 70% attenuation.

Sweet Stout: mash 154F, 64% attenuation when I back calculate out the lactose addition.

 

[Bobby_M]

The variables are really what I was trying to establish. I assume you used the same thermometer for mash temps. Did you check at the same points in the mash duration, like after 5 minutes, 30 minutes, 60 minutes? I agree that if the average temp over the two mashes were really 5F apart, that you did get odd results but that's discounting measurement variation, pitching rates, yeast health, fermentation temp variation, etc.

 

[ajdelange]

At 157 you got (56 - 14)/56 =75.0 %
At 152 you got (54 - 14)/54 =74.07%

So clearly attenuation increases with mash temperature. Right? Only if the tolerances in your estimates are very tight. If you mismeasured either the initial or final with accuracy such that the error in the attenuation estimate is 0.1% or better then the rate of change of attenuation with temperature is, with 68% probability, between 0.209 and 0.158 %/°F. If, OTOH, the standard error in your measurements is 1% (a much more realistic number) then the rate of change of attenuation with temperature is between 0.469 and -0.097. IOW the data you have is not sufficient to demonstrate that the slope is either positive or negative with appreciable statistical precision. It is sort of like stopping at a gas station in West Virgina and observing a male attendant and male customer and concluding that all West Virginians are male. If you found that the attenuation increased with temperature over scores of measurements then we would be having a different conversation.

 

[feinbera]

Heh, it's even worse than that -- with different malts and yeasts, it's like he's sitting in West Virginia right by the Ohio border, and draws the same conclusion looking at a male West Virginian farmer and a male dog across the border in Ohio.

 

[bigskygreg]

Heh, it's even worse than that -- with different malts and yeasts, it's like he's sitting in West Virginia right by the Ohio border, and draws the same conclusion looking at a male West Virginian farmer and a male dog across the border in Ohio.

I actually get that ad I'm from pa

 

[frazier]

All males, Huh? Well that explains how I got that black eye back in '02.

Anyway, I do think it's funny that we often see threads asking "Why is my FG so high?", and here with the opposite problem, I was really just blowing off a little steam. "Better luck next time" seems like a good answer.

 

[MarcusKillion]

my gravity is almost always 1.011 or so . Unless I brew a kit then it is 1.008 got no idea why . but real low is either real good or real bad I think .

 

[Cathedral]

I can tell you for sure that different mash temps makes a big difference. I brewed two smash's--the only difference is the hops--only on the second one my mash temp ran away from me (new burner!) and it got up to 158(!!!) while I was trying to keep it at 150. The first batch I kept at 150 since it was on equipment I was used to.

My 158 smash is very full bodied, sweet, and lingers on the tongue forever.

My 150 is crisp with a slight body, not sweet, and only lingers for a second or two.

Both were the same grist bill with only one malt, the only difference was the hop used (hence SMaSH.)

That being said, I think I actually enjoy the experience of the 158 better. Since it lingers around, you get to really feel it and taste it. It has definitely changed the way I plan on brewing the rest of my beers.