High mash temps

Do high mash temps affect FG?

I brewed my second all grain they dont seem to be getting lower than 1.020 .

I brewed a witbier, 50/50 flaked wheat and two row. I mashed a little high for various reasons (too many beers mainly) couldnt get the temp to go down so i gave up on it and let it sit at 158/159 for most of the mash (could have been a little higher not sure thoguh). It was quick to ferment but stopped bubbbling after 48 hours and the Gravity is only down 1.024. Ive been gently rousing the yeast everyonce in a while but cant get anything out of them. IM not too worried i tasted a sample today and it was good ( only @ about four days old) thats all that reaaly matters, i would just like to get it right in the future. IF thats not the case i think i need an oxgenation kit.

Oh i pitched dry yeast unhydrated (not sure which kind i should start writing that down) blue package.
Fermentation has been at 68 on the dot

Yes, those high temps will still convert starch to sugar, but LONG CHAIN sugars, which the yeast cannot convert to alcohol... so yes, that is the issue more than likely.

Take a look at the rim of your primary and look for any rich, pudding like krausen residue. A lot of yeast may get "beached" up there. If that is the case, swirl your primary to knock it back into suspension.

I had this exact problem with a Belgian Wit, but I used a White Labs Belgian Yeast...notorious for an explosive krausen.

ahh okay glad to hear that (kinda) i like to learn from my mistakes, best way to learn. No sense in repitching or anyhitng like that right?

NO it was a quick ferment so nothing got stuck on the sides just a very small indication that it had been there but not long enough to stick. (its you wit muncher btw) Tasted the sample today and it was very simmilar to blue moon like you said.

John Palmer's online book howtobrew.com has pages about the chemistry behind the temperatures. It's good reading and I think it'd be worthwhile to read. The gist of it ends up being:

What do these two enzymes and temperatures mean to the brewer? The practical application of this knowledge allows the brewer to customize the wort in terms of its fermentability. A lower mash temperature, less than or equal to 150°F, yields a thinner bodied, drier beer. A higher mash temperature, greater than or equal to 156°F, yields a less fermentable, sweeter beer. This is where a brewer can really fine tune a wort to best produce a particular style of beer.


I've mashed at 147 for a beer that finished at 1.006 and at 154 for a beer that finished at 1.018. Yes, there are some other factors, too- the amount of unfermentables and "sweeter" malts. If you use a ton of crystal, for example, it'll be a higher f.g. But temperature plays a huge role in the fermentability of the mash.

Ahh thanks thats ill remeber thatt next time i havnt read that in a while maybe i should look over it again!

I'm guessing that your high FG is because you used flaked wheat. not wheat malt.