mash temps and estimated final gravity

[JLem]

I use BeerSmith to calculate recipes, but I noticed that it gives the same estimated final gravity no matter what mash temp I set. It is my understanding that a lower mash temp will yield a more fermentable wort, thus should produce a potentially lower FG than a wort mashed at a higher temp. Are there any guidelines for how much the mash temp affects an estimated FG? Any idea for what temp BeerSmith is "calibrated" at?

 

[Scimmia]

It just uses whatever average attenuation you enter for your yeast. No adjustments for mash temp, crystal malt, maltodextrin, etc.

 

[JLem]

It just uses whatever average attenuation you enter for your yeast. No adjustments for mash temp, crystal malt, maltodextrin, etc.

So, is there a way to take those things into account? For example, if I mash at 158F should I add 2 points to the anticipated FG?

 

[Kaiser]

So, is there a way to take those things into account? For example, if I mash at 158F should I add 2 points to the anticipated FG?

I have done a lot of work on the effects that mash parameters have on attenuation but won't be able to give you a formula for that. The problem is that there are so many factors that have an effect and while temperature might be the most important one the others cannot be neglected. When I started AG brewing I was asking the same question and was disappointet when nobody could tell me how to mash to get a targeted attenuation.

Now, after almost 100 batches, I do have a extensive collection of notes where I can go back and look for similar beers for which I have data and adjust the mash schedule from there. Two other things might be of interest for you to gain better insight into that subject:

- Attenuation - tells you about attenuation and how it is affected in mashing and fermentation
- Fast Ferment Test - is a very useful test that allows you to test the fermentability of the wort you produced in mashing w/o the effects that yeast characteristics can have during a regular fermentation. I perform that test for every batch and it tells me 2-4 days after brewing if my mashing produced the desired fermentability. In fact I got a surprise last batch when I brewed an Alt where the fermentability was lower than targeted. The next batch, when I brew the same recipe again, I'll mash longer at the lower temp to get better attenuation. The low fermentability was likely caused by the Munich malt I'm using and it requires me to mash differently compared to a Pilsner or 2-row mash when I want the same attenuation.

Kai

 

[JLem]

Kai - thanks for the links (and for doing and sharing the results of your experiments). I understand what you mean by there being a lot of factors affecting the fermentability of the wort. It seems though, that the data you present in Figure 11 in Effects of mash parameters on fermentability... could offer some good, if rough, guidelines for the info I was originally looking for, especially for the warmer mash temps.

EDIT: just noticed though that most of the mash temps where there appears to be a linear relationship (68C+) are quite warmer than I would consider for a mash. Generally I keep my mash between 150F and 158F, so my original thought for Figure 11 doesn't help me too much. I'm curious as to why you tested such high mash temps?