Mashing Temperatures

[conspiccus]

Hi all, last weekend I brewed I milk stout with the recipe listed below. I wanted to mash around 68 because i read that it will create more unfermentables and give me a thicker mouthfeel at the end, which is what I was looking for in a stout. I mashed in at 69 (assumed the grains would bring the temp down a degree), put the lid on and tuned the heating element off my buffalo boiler (I do BIAB). I checked 10min later and my thermapen read 71 degrees. I panicked and took the lid off and started mixing to hopefully dissipate some heat. Not sure what my logic was behind this, sorta panicked and thought it might help. I managed to get my temp down to 69 and it stayed there for the remainder of the mash. The SG was 1.064 and I am hoping to get it down to around 1.014. I checked this morning and I am at 1.030. I have had a problem of mashing waaayyyy too hot before when I had a thermometer issue, but I trust the thermapen didn't think that 1-2 degrees would make this much of a difference. I have read that alphas work best 67-72 and betas work best 55-65 so have I simply denatured all my betas in only 10 minutes? Any thoughts or advice are much appreciated!

12L batch

Grain bill:
2.5kg pale
300g crystal
230g roasted barley
180g chocolate
150g flaked barley
150g rolled oats
50g black malt

Hops (IBU=29):
14g challenger at 60min
15g cascade 10 min

Extras:
250g lactose sugar at 15min left in boil

Yeast:
10.5g Safale US-05

Water:
mash pH = 5.34
Ca2+ = 122, Mg=12, Na=38, Cl=181, SO42-=52, HCO3- = 126

 

[Holden Caulfield]

There is a lot of good information in this thread about temperature: Mash Temps importance

71 is 160f which is very warm and will denature the Beta Amylase rapidly. Per the chart from Braukaiser, it looks like most of the beta activity will be reduced in under 10 mins. Even at 69 it will denature rapidly.

I checked 10min later and my thermapen read 71 degrees

Given you checked your temp after 10 mins and found it to be 160 degrees, you probably did reduce the beta activity substantially and should expect attenuation to be on the very low side.

As far as attenuation, here is a chart that aggregates a number of studies on temperature and fermentability for 60 minute mashes. Based on the chart, you should expect attenuation % to be ~10 percentage points lower than you expected. Maybe even lower as you measured 71 after 10 mins.

I am not an expert on fixing this issue, but it may be possible to add an enzyme to the fermenter to break down the large sugar molecules and restart fermentation.

 

[conspiccus]

There is a lot of good information in this thread about temperature: Mash Temps importance

71 is 160f which is very warm and will denature the Beta Amylase rapidly. Per the chart from Braukaiser, it looks like most of the beta activity will be reduced in under 10 mins. Even at 69 it will denature rapidly.

View attachment 702974


Given you checked your temp after 10 mins and found it to be 160 degrees, you probably did reduce the beta activity substantially and should expect attenuation to be on the very low side.

As far as attenuation, here is a chart that aggregates a number of studies on temperature and fermentability for 60 minute mashes. Based on the chart, you should expect attenuation % to be ~10 percentage points lower than you expected. Maybe even lower as you measured 71 after 10 mins.

View attachment 702975

I am not an expert on fixing this issue, but it may be possible to add an enzyme to the fermenter to break down the large sugar molecules and restart fermentation.

thank you, this is exactly what i was looking for!