reverse step mash

[Owly055]

I've read a lot about alpha and beta amylase, and it seems backward to me to step UP in temp. Logic says you should step down. Alpha operates at a lower temp, and beta at a higher temp. Beta breaks the chains down into large chunks, and alpha nibbles off the ends. Why wouldn't I start at 165, and simply allow the mash to cool down to 145 over the course of a few hours instead of stepping up, or holding a constant 152 or so....... Provided my goal was maximum fermentability / conversion and a very dry beer?

H.W.

 

[AnOldUR]

Why wouldn't I start at 165, and simply allow the mash to cool down to 145 over the course of a few hours.

Beta enzymes denature at around 158 degrees.

 

[Crucial-BBQ]

The simple answer is that at higher temps beta amylase becomes denatured. I am not sure if it will become fully denatured at 165˚F, though.

Also, to my knowledge beta amylase only produces maltose where as alpha amylase also produces maltose as well as glucose, maltotriose, and dextrins.

Percent fermentability = % alpha amylase fermentable products + % beta amylase fermentable products, which can only be achieved by stepping up in temp. What you propose is more like Percent fermentability = % alpha amylase fermentable products - (% beta amylase fermentable products+ C), where C is some constant.

So, alpha operates at a higher temp with beta operating at the lower temp, just so you know.

 

[Owly055]

Beta enzymes denature at around 158 degrees.

I guess I had alpha and beta mixed up................... After reading your post, I did a bit more reading....... I thought beta was not destroyed until a higher temp. The term used is "deactivated". I don't think that means the same as destroyed. I would presume that when the temp drops back into range it is "reactivated". The term "deactivate" suggests that it simply quits working, as opposed to "denatured" which would imply a permanent chemical change. The literature is not clear on this.

In support of your assertions, I recently did a mash at 162, and the result was a not highly fermentable brew..... which was the goal, but I never dropped the temp back into the beta range. My next brew will be a 2% Mosaic Rye Wit... mashed at 152, but after that, I'm going to try a pale ale (2.5 gallon) starting the mash high...... About 162, and after half an hour or so, pull the insulation from around my pot (foam and blankets), and allow it to drop down below 150 (maybe help with cold water), and hold it there for an hour or so. This should allow me to see what happens with OG and FG.

I don't personally believe that either alpha or beta is "denatured" until around 170. Charts showing mash temps and attenuation would tend to support this.

fermentability [Narziss, 2005]:
Temperature 140ºF (60ºC) 149ºF (65ºC) 160ºF (70ºC) 167ºF (75ºC)
attenuation 87.5% 86.5 % 76.8% 54.0 %

The only way to draw a meaningful conclusion is to try it by brewing two brews identical except in the mashing schedule. The hydrometer readings should more or less tell the tale.

H.W.

 

[AnOldUR]

The term used is "deactivated". I don't think that means the same as destroyed.

Here's the chart I go by.

When temperature goes much above their optimal rate, the reaction rate will drop off very quickly and the enzyme may start to denature (the enzymatic death that happens when the structure of the enzyme itself breaks down).

 

[VikingChrisColby]

You could do a step down mash, but you'd need to stir in fresh malt when the temperature drops. (In fact, stirring in the malt would cool the mash somewhat.)
Beta-amylase is progressively denatured at higher temperatures and by the time you cooled the mash down, there would be little enzyme activity left. (There would be some activity, but maybe not enough.)
If you wanted a maximally fermentable wort, your best bet would be to start the mash at around 162 °F. Hold for about 15 minutes, then stir in the remaining malt (and whatever water you need) to bring the temperature down to around 140 °F. The second dose of malt would probably need to be roughly the same amount as the first. Hold for about 2 hours at 140 °F. (Or, to save time at the expense of a small amount of fermentability, hold for about 1 hour at 150 °F.) This should make a very fermentable wort.
Incidentally, to get a better grasp on how enzymes work, check out this article I posted on my website. (My graduate work was in molecular biology and evolution.) There are a lot of misconceptions about how enzymes work in the brewing community.

Enzymes for Brewers
http://beerandwinejournal.com/enzymes-i/


Chris Colby
Editor
http://beerandwinejournal.com

 

[MrKrinkle151]

The term used is "deactivated". I don't think that means the same as destroyed. I would presume that when the temp drops back into range it is "reactivated". The term "deactivate" suggests that it simply quits working, as opposed to "denatured" which would imply a permanent chemical change. The literature is not clear on this.


H.W.

It means denatured. If lowering temperature reversed the structural change of the enzyme, then cooling down fried eggs would turn the cooked whites back to clear liquid.

 

[Owly055]

Here's the chart I go by.

That's a great table.......... I do however think the numbers for beta are questionable. There is obviously an overlap range or a single infusion mash would not yield much at all. I've been mashing at about 152 which according to that chart would be out of range for both.

I'm tempted to run a mash at a strike temp of about 156, insulate well and go for 3 or 4 hours just to see what kind of attenuation I get. Clearly the higher we go within the range below where alpha is denatured, the more the two are going to operate together.

Interestingly enough in some literature alpha and beta are reversed with alpha being the high temp long chain amylase, and beta being the lower temp variety that produces maltose. Here is one reference that lists them reverse of what people have been telling me here........ No wonder I'm confused!! I'm obviously not alone.


H.W.

 

[peterj]

The term used is "deactivated". I don't think that means the same as destroyed. I would presume that when the temp drops back into range it is "reactivated". The term "deactivate" suggests that it simply quits working, as opposed to "denatured" which would imply a permanent chemical change. The literature is not clear on this.

They are denatured. They can't be remade. I have found the literature to be very clear on that. If something you're reading is saying deactivated they are probably using it interchangeably with denatured.

I don't personally believe that either alpha or beta is "denatured" until around 170. Charts showing mash temps and attenuation would tend to support this.

It's not really about personal beliefs. Heat denatures enzymes. Even in their ideal range they are being denatured. But the reason they do not work too far above that range is because they become denatured at a much faster rate.

That's a great table.......... I do however think the numbers for beta are questionable. There is obviously an overlap range or a single infusion mash would not yield much at all. I've been mashing at about 152 which according to that chart would be out of range for both.

The more heat that is in a system the faster the reaction will progress, so the more heat you add the faster the enzymes will work until they get to the point when they are being denatured faster than they can perform the reactions. But it's not like an on/off switch. It's a sliding scale, which is why there are ranges, and that's also why mashing at 152 works. It's a little hotter than beta amylase likes it, but not so hot that it is denatured before it can perform the amount of conversion that you want it to. 152 is also a little cooler than alpha amylase likes it, so it's not quite as active as it would be if you mashed higher. So mashing higher favors the alpha and denatures the beta at a faster rate leaving a less fermentable wort, but mashing lower allows the beta to do more of it's work without being denatured too quickly and thus produces a more fermentable wort.

I'm tempted to run a mash at a strike temp of about 156, insulate well and go for 3 or 4 hours just to see what kind of attenuation I get. Clearly the higher we go within the range below where alpha is denatured, the more the two are going to operate together.

At 156F I would imagine the beta amylase would be denatured fairly rapidly so you would have a pretty set fermentability profile in much less time than 3 to 4 hours. Because the speed of a reaction increases with the heat in a system many people who are mashing in the higher range (156-158) will only mash for 45 minutes or so.

 

[AnOldUR]

That's a great table.......... I do however think the numbers for beta are questionable.

The temperature ranges listed on that chart are optimal conditions. The enzymes will work outside of them unless denatured, but be effective to a lesser extent. The thing about your 3-4 hour mash at 156 is that all the Beta Amylase will not be denatured and will continue to break down sugars already converted by the Alpha Amylase. Depending on the accuracy of your thermometer and how close to denaturing you actually are, you could end up with a highly fermentable wort. This is the reason mash-outs are sometimes necessary.

 

[IslandLizard]

That's a great table.......... I do however think the numbers for beta are questionable. There is obviously an overlap range or a single infusion mash would not yield much at all. I've been mashing at about 152 which according to that chart would be out of range for both.

I'm tempted to run a mash at a strike temp of about 156, insulate well and go for 3 or 4 hours just to see what kind of attenuation I get. Clearly the higher we go within the range below where alpha is denatured, the more the two are going to operate together.

Interestingly enough in some literature alpha and beta are reversed with alpha being the high temp long chain amylase, and beta being the lower temp variety that produces maltose. Here is one reference that lists them reverse of what people have been telling me here........ No wonder I'm confused!! I'm obviously not alone.


H.W.

You can make small mash test batches of say a pound of grain each and see what happens when boiled, fermented out with the same yeast, all at the same temps and time. Some literature have wrong references indeed, and that's confusing.

John Palmer's graphic has their activity ranges correctly pictured. Denaturing happens gradually and more so with increasing time and temps. And like the egg example, irreversibly.

 

[Owly055]

I find it interesting that people are in such disagreement as to which is Alpha and which Beta. I was originally corrected when I referred to the low temp amylase as Beta and the higher as Alpha............. which seems to be correct. Perhaps we should take a vote ;-) The fact is that it really doesn't matter which is which except conversationally.

H.W.

 

[peterj]

I've read a lot about alpha and beta amylase, and it seems backward to me to step UP in temp. Logic says you should step down. Alpha operates at a lower temp, and beta at a higher temp. Beta breaks the chains down into large chunks, and alpha nibbles off the ends. Why wouldn't I start at 165, and simply allow the mash to cool down to 145 over the course of a few hours instead of stepping up, or holding a constant 152 or so....... Provided my goal was maximum fermentability / conversion and a very dry beer?

H.W.

I find it interesting that people are in such disagreement as to which is Alpha and which Beta. I was originally corrected when I referred to the low temp amylase as Beta and the higher as Alpha............. which seems to be correct. Perhaps we should take a vote ;-) The fact is that it really doesn't matter which is which except conversationally.

H.W.

Well actually you originally referred to the Alpha as low temp and Beta as high temp.

Beta amylase is the one that operates at a lower temp and Alpha at a higher temp. That's what it is and there isn't disagreement about it. I have however, seen many people inadvertently switch these two (as you did originally). But that's true, they don't care what we call them! They will still work and help us make beer either way!

 

[Nubiwan]

Beta enzymes denature at around 158 degrees.

Do they? I have my doubts.

 

[Gnomebrewer]

Do they? I have my doubts.

They definitely denature after 7 years at 158 degrees.

 

[Nubiwan]

Sorry to revive an old thread, and not sure anyone other posts or newer literature exist, but I frequently begin my mash around 158 degrees, and just let it sit for 90 minutes and drop of its own free will to 142 degrees. My theory is i get eh benefit of both enzymes, and dont have to worry about babysitting pots of hot water, heating etc. It might be a load of balls.

It is an uncontrolled reverse step mash of sorts I've read multiple people say that Beta Amylase is denatured doing it this way. My response is that I should expect a pretty high final gravity, because I denatured my Beta. Is that a correct assumption.

In my last pilsner, my OG was 1.044 and my FG is 1.006. Should I have expected that? I very rarely have a beer finish over 1.010 doing to this way. Granted, these are not high gravity beers I make.

 

[Gnomebrewer]

There's not some magic temperature where enzymes suddenly denature, they denature faster at higher temperatures. 158 is at the fast end of the curve for Beta amylase (it's denaturing fairly quickly) but there will still be some left if it's not held at 158 for too long. I find a longer mash affects mash fermentability as much as lower temperatures, so I'm not surprised that your 90 minute 'reverse' mash is highly fermentable.