How much of an FG swing can be expected from a change in mash temp?

[Nizmoose]

Hi guys,
The title says most of it just wondering if anyone has a good ballpark figure for how much your FG may change from your expected FG purely from a high mash temperature. I have done a bit of reading and I understand that there are several factors at play here such as grain bill, yeast health, strain etc but I'm after a ballpark figure of how much your FG can be altered by changing only mash temp. I ask because I have an english bitter which I tested today after 10 days in the fermenter. It's reading 1.014 and has been sitting in the 16-17C range for the 10 days. I'm not worried about a stuck fermentation or anything as I am confident it'll munch up what it needs to and my beers sit in the primary for 2.5-3 weeks anyway so it has plenty of time. My malt bill was fairly standard mainly maris otter with around 6% crystal but I wanted a beer with quite a bit of body so my main sacc. rest was done at 68 which I know will pull my FG up from the predicted 1.008, my question is by how much? I'm guessing that 1.010-1.012 is close but have no idea and am interested. Cheers.

 

[manticle]

Too many variables as you suggest to give anything specific. I'd not be surprised at a 1014 finish from a 68 mash though.

 

[1974Alby]

really interested in this...assuming the same grain bill, mash duration, yeast amount, aeration etc, if a 68C mash gives 1.014, what FG would one expect from say a 63C mash?

 

[Nizmoose]

Too many variables as you suggest to give anything specific. I'd not be surprised at a 1014 finish from a 68 mash though.

Yeah I assumed theres a lot at play and its hard to narrow down, good to know that 1.014 might be it, the sample tasted awesome

really interested in this...assuming the same grain bill, mash duration, yeast amount, aeration etc, if a 68C mash gives 1.014, what FG would one expect from say a 63C mash?

I'm not sure how up to speed on the biology of it I am but I believe the apparent attenuation of the yeast should indicate an FG around the norm so lets say you mash at 65 and your yeast should get you to around 1.008 I'd expect a looooong mash at 63 to give you a noticeably lower FG perhaps 1.005ish, hopefully someone more knowledgeable can chime in because it'd be good to know how much your FG can change based purely on mash temp and duration, will probably end a few 'is it finished yet?' threads as well.

 

[dicko]

Brad Smith is apparently researching this very subject at least according to a post he placed on the Beersmith forum, and in time intends to build an equation into his software.

I know this doesn't help you Nizmoose but at least someone else is thinking about it.

Manticles' rough assessment would be close if I go on some of my results over the years.

 

[Eagleburger]

I reckon about 6 points between 65 and 68. Lower tthan 65 didn't seem to change it much according to my uncalibrated brewing. I tried to replicate the brews as much as I could but there was volume and efficiency differences in the initial ones. I have run out of crystal I was using so will omit it and keep experimenting. Increasing ferment temp over time lowered fg by 2 points.

BB ale crystal and roasted malt. Same proportions.
CB american ale yeast 24g
50 L of 1050
Custom ferment profile18- 24degC for seven days.
65degC gave 1007, 68degC 1013.

An earlier brew mashed at 62 gave 1007 as well. But I brewed that before I thought about experimenting so wasn't to critical about well anything.