Attnuation And Mash Temp

[Sammus]

A recipe I want to try is mashed at 67C, has predicted OG at 1.062 and FG at 1.015. Thats about 76% attenuation I think, which is within spec for the recommended yeast (1020, 72-77% IIRC). I want to use a different yeast that is rated by wyeast as 67% - 71%. In BCS they say to mash lower or replace some base malt with sugar to help less attenuative yeasts reach FG.

Is there any way to calculate how much a difference in mash temp will affect how attenuative the yeast is? If Wyeast rates my substitute as max 71% atten, then surely even if mash at 62C, or had a 100% glucose mix for that matter, it still wouldnt attenuate as much as we want it to?

 

[MHB]

I suspect that what your saying is about right, the yeast won't go much out of its stated attenuation range no matter what the wort has available, naturally if there aren't enough fermentables it can't eat them.
Other variables would include yeast health, pitch size, oxygenation of the wort and contact time to name a few.
I think you are going to have to match your yeast to the attenuation you're looking for.

Determining the fermentability based on mash temperature came up a couple of years ago, Wheelers' books gave some basic information, Wes Smith suggested that the information was pretty dated and that with modern malts it takes a lot bigger change in mash temp to get a change in the fermentable/dextrin ratio. Just one of those things you will have to test brew and determine what works best for you.

MHB

Found the thread
M

 

[Sammus]

Cheers for digging that up. Do you know if a low mash temp affect the taste significantly other than the potential dryness associated from greater attenuation?