Achieving Lower Attenuation

[TastyAdventure]

It seems I am always getting higher attenuation than the estimate for any given yeast strain. I'm either at the highest part of the estimated range or over.
This is across all batches but one partial mash I did a long time ago where I mashed at 160...

I batch sparge, have mashed between 149 and 157 (intentionally), used several different strains.
Don't use yeast nutrients, I aerate just make shaking and stirring. Usually ferment between 65 - 69 F, and ramp it up to 70 near end of ferm.

What gives?

 

[Yooper]

It could be several things. One is something simple like not mashing out, or reaching mash out temperatures quickly, so the enzymes continue to work and create more fermentable wort.

When I batch sparge, I start my first runnings onto boil immediately and that works as a 'mash out'.

I assume that you have calibrated your thermometer and it's accurate, of course.

A thinner mash is said to favor more fermentable wort, but in my experience it hasn't been the case. Also, simple sugars will ferment more completely than long-chained sugars, so using something like corn or corn sugar vs a more highly kilned malt like Munich 20L means that it would be more fermentable than the one with the darker grains.

 

[TastyAdventure]

It could be several things. One is something simple like not mashing out, or reaching mash out temperatures quickly, so the enzymes continue to work and create more fermentable wort.



When I batch sparge, I start my first runnings onto boil immediately and that works as a 'mash out'.



I assume that you have calibrated your thermometer and it's accurate, of course.



A thinner mash is said to favor more fermentable wort, but in my experience it hasn't been the case. Also, simple sugars will ferment more completely than long-chained sugars, so using something like corn or corn sugar vs a more highly kilned malt like Munich 20L means that it would be more fermentable than the one with the darker grains.

I'm glad to see you here Yooper.

I usually mash for 60 min, mash out up to ~165, get heat under my first runnings as soon as it hits the kettle.

Thermometer should be good...

I always max out my mash ton with about 23 lbs of grain at 1.25 at/lb. So thick mashes too.
Usually using a decent amount of specialty malts and sometimes simple sugars, but it always accounted for those.

Also, when I use liquid yeast, I usually make a small, short, half assed starter unless gravity or volume is really high, then I'll make a big one.

Would mashing for just 30 minutes help?

 

[zachattack]

Thermometer should be good...

Why do you say "should be"? Have you checked it in a proper ice bath and in boiling water? If you haven't, it's definitely worth checking, just to rule it out. I've had some thermometers be off by 8 degrees right out of the box.

 

[RM-MN]

Would mashing for just 30 minutes help?

I think these two threads may help you a bit.
https://www.homebrewtalk.com/f36/controlling-attenuation-through-mash-times-60576
/https://www.homebrewtalk.com/f244/mash-heresy-tale-3-brew-sessions-519615/