Alpha amylase levels in grain

[CWood]

Hey Folks-

I've searched the web and found a little bit of info, but still can't find an answer to how levels of alpha amylase in malted grains impact a mash in relation to mash temp. In other words, if one grain has a lower level of alpha amylase than another, would a higher mash temp be less efficient at converting starches to more simple sugars to be further broken down by beta amylase? I usually pay more attention to diastatic power as a measure of how efficient a grain is at conversion, but that is a combo of alpha and beta. I often use mash temp to control fg, and thus mouthfeel/body, instead of adding dextrin malts (carapils, etc.). I recently started using a grain that performs great at lower mash temps (149-152), but when I mashed it at 156 (single infusion batch sparge) for a recent brew to gain a little more body, I had a much higher fg than expected. I looked into the specs and saw it had a much lower alpha amylase value (33.1) than other malts from the same maltster. I know that at 156+ beta starts to degrade and alpha is favored, but I just can't wrap my head around the alpha levels and why higher temps would impact it so much more than a similar malt with higher alpha levels. Someone enlighten me! Thanks!

I should say I'm pretty comfortable with the yeast I was using (Cali lager) and my brewery. I tried the usual approaches to get a few extra points (swirled the carboy, increased temps, etc.), but this sucker is done fermenting. At the end of the day it taste great in the hydro flask and isn't sweet at all, so I made a beer, just didn't come out as planned...... the fun part of using new malts!

 

[user 125772]

Your experience with the low and high mash temps is totally normal... that's why we use 156 for stout and 148-150 for IPAs


Here is a diastatic power chart for some of the more common malted grains:

Malt Degrees Lintner

Briess Red Wheat Malt 180
Briess White Wheat Malt 160
Briess Two-Row Malt 140
Briess Pilsen Malt 140
Briess Vienna Malt 130
Briess Rye Malt 105
Briess Munich Malt 10L 40
Briess Caramel 20-120 0
Briess Chocolate Malt 0
Briess Black Malt 0

just google "diastatic power chart"

 

[CWood]

Your experience with the low and high mash temps is totally normal... that's why we use 156 for stout and 148-150 for IPAs


Here is a diastatic power chart for some of the more common malted grains:

Malt Degrees Lintner

Briess Red Wheat Malt 180
Briess White Wheat Malt 160
Briess Two-Row Malt 140
Briess Pilsen Malt 140
Briess Vienna Malt 130
Briess Rye Malt 105
Briess Munich Malt 10L 40
Briess Caramel 20-120 0
Briess Chocolate Malt 0
Briess Black Malt 0

just google "diastatic power chart"

Thanks for the reply. I understand that, I think maybe I'm asking
the question wrong. Diastatic power is a combo of alpha and beta, so my question is if two grains have the same dp, but one has less alpha amylase than the other (therefore higher beta), then my current experience is that a high mash temp will leave even a higher FG than the malt with the greater alpha levels (although their dps are the same). Does that make sense? I usually don't see a specific value for alpha listed for malts, but in the case of the malt in question it is given. I've used other malts with similar dp and can predict what a high mash temp will result in, but in the case of this new malt with lower alpha levels it has a much higher fg than anticipated. Im trying to understand the chemistry behind that.

 

[doug293cz]

Thanks for the reply. I understand that, I think maybe I'm asking
the question wrong. Diastatic power is a combo of alpha and beta, so my question is if two grains have the same dp, but one has less alpha amylase than the other (therefore higher beta), then my current experience is that a high mash temp will leave even a higher FG than the malt with the greater alpha levels (although their dps are the same). Does that make sense? I usually don't see a specific value for alpha listed for malts, but in the case of the malt in question it is given. I've used other malts with similar dp and can predict what a high mash temp will result in, but in the case of this new malt with lower alpha levels it has a much higher fg than anticipated. Im trying to understand the chemistry behind that.

One way to look at it might be: the higher the Beta to Alpha ratio for a given DP, the faster the DP will drop as a function of time at any given temperature. The faster the DP drops over time, the longer you have to extend the mash to achieve max fermentability. Once DP drops to zero, you will get no more conversion, or increase inf fermentability. So, once DP goes to zero, any extended mash time does zilch. Thus a lower beta/alpha malt will often produce less fermentable wort for a particular mash time & temp choice.

Brew on

 

[Qhrumphf]

The way that enzymes work, they don't get used up. They will continue to work until being denatured. A lower alpha amylase content shouldn't matter much as even in a relatively hot mash (158+) it's still quite temp stable.

Alpha also randomly cleaves up starch chains, leaving many unfermentables behind. If I recall correctly, it also has limits to how far it'll cleave, and as such limits fermentable sugars as well.

Basically if your FG is high, not enough alpha probably isn't your problem.

Beta is your issue.

Some grains will indeed perform better at a given temp than others. With that grain you may just have to mash lower, or consider a step mash- a brief rest in the mid 140s to allow beta to break off the chain ends, and then ramp it to 156 for alpha to do the heavy lifting.

 

[CWood]

Good stuff guys, thanks.

 

[mongoose33]

Check out this article:

https://missionarybrewer.wordpress....ers-window-what-temperature-should-i-mash-at/

To save you a bit of searching, here's the graph at the end of the article; I think it's what you're looking for:

 

[CWood]

Thanks!