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Does mash temp affect SG or FG?

My buddy and I keep arguing over this. Looking for some other opinions.

I understand that the temperature of the mash affects the fermentability of the wort however will it have an affect on the starting gravity or the final gravity?

He thinks that it will change the efficiency(starting gravity/efficiency) and I think it will change how far the beer will ultimately ferment(final gravity/attenuation)

You are correct, it will change the final gravity. The only way it could change the OG would be if you were WAY under or over temp.

I actually did a recent experiment with this. I brewed 2 6 gallon batches of Dead Ringer IPA (with some minor personal changes). Identical grain bills, etc.
Batch 1 = 150 degree mash
Batch 2 = 155 degree mash

I also split both batches in half, fermenting 3gallons of each with 1056 and 3 gallons of each with 1272.
So, I ended up with 3 gallons of four slightly different beers:
150 mash/1056 yeast
150 mash/1272 yeast
155 mash/1056 yeast
155 mash/1272 yeast

Both had same starting gravity of 1.055

There was no difference in Finishing gravity between the 1056 and 1272 yeasts. within the same mash temp. However, there was a small difference in finishing gravity between the 150 and 155 mash temps.
1.014/15ish in the 155 batch
1.012ish in the 150 batch

Not a huge difference, but noticeable.

i have not compared them yet for taste etc. as I just bottled them about 2 weeks ago. Maybe try a couple of them later today and see how they are doing.

At NHC, Greg Doss from Wyeast presented a seminar on a mash temp experiment he did. He actually found maximum fermentbility at 153F, although he said he wannts to do more experimentation. This was under closely controlled lab conditions. The experimental results should be online in the next week or so.

Thanks for the comments guys! That’s what i figured and what I remember reading in Palmer’s book. Just wanted to get more opinions!

Looking forward to seeing those results Denny! thanks for the info!

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