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Alpha Amylase And Beta Amylase - Temp Ranges?


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#1 manticle

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Posted 24 February 2012 - 04:48 PM

Just trying to answer someone's question in regards to step mashing, I checked george fix: priciples of Brewing Science.

In that he disusses alpha amylase activity leading to maltose production and operating between 60 and 65 deg C.
Beta amylase activity leads to breakdown of starch to dextrins and occurs between 65 and 70.

I've seen posts around where people refer to beta amylase operating at the lower temp and alpha at the higher and found this home brew wiki which suggests the exact opposite to Fix and with a wider temp range

Beta amylase produces Maltose, the main wort sugar, by splitting 2 glucose molecules from the non-reducing end of a glucose chain. It is therefore able to completely convert Amylose. But since it cannot get past the branch joins, Amylopectin cannot completely be converted by beta amylase. The optimal pH range for beta amylase between 5.4 and 5.6 and the optimal temperature range is between 140F (60C) and 150F (65C). Above 160F (70C) beta amylase is quickly deactivated [Narziss, 2005].

Alpha Amylase is able to split 1-4 links within glucose chains. By doing so, it exposes additional non-reducing ends for the beta amylase. This allows for the further conversion of Amylopectin. The optimal pH range is between 5.6 and 5.8 and the optimal temperature range is between 162F (72C) and 167F (75C). Above 176F (80C) alpha amylase is quickly deactivated [Narziss, 2005]


Now I don't have access to Narziss to see if they have misquoted him and my inclination would be to trust Fix. I have other books and documents about I can check but can those with an inkling of understanding of the brewing scientific principles make it clear who is correct and who is incorrect.? I've re-read both a couple of times to make sure it's not me misinterpreting as someone, somewhere has made a serious error.

Edited by manticle, 24 February 2012 - 04:51 PM.


#2 QldKev

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Posted 24 February 2012 - 05:06 PM

Not quoting any books etc, but just my understanding/experience

In the perfect world keep the Beta down in the range 60-62
and the Alpha in the higher end of the range, say 68, even up to 72. But if you are pushing the temps high in the beta range, you need to mash longer.

In my words, the higher the temp the longer the mash.

But it is safer to mash closer to the 66.5 as it keeps the enzymes happy campers. Hence why you may read posts about limiting the range. IMHO if you want a total of a 60min mash don't touch 70.

Also depending on the beer style,
say an APA and you really wanted to have a couple of steps, I would pack them closer.
but a full on Pils I would think a 62 and 72 would be excellent.


edit: Fixed up incorrect Alpha and Beta ranges when I got home and re-read it from the pc


QldKev

Edited by QldKev, 24 February 2012 - 05:49 PM.


#3 felten

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Posted 24 February 2012 - 05:16 PM

That is very strange indeed, all the info I've ever read/heard says the same as the Narziss quote as well.

#4 manticle

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Posted 24 February 2012 - 05:18 PM

Pretty much my understanding also Kev from reading and experience. I often mash short at 62/62 then higher and longer at 67/68.

I find with simple grain bills especially, this gives well attenuated beer with good maltiness and body. However if the wiki is wrong it needs correcting (as it's demonstrably wrong).

If Fix is wrong, even though he's no longer here, I think possibly the correction needs to be added to the next edition.

Just reading a section in Handbook of Brewing (ed Elinger) that has alpha amylase at 65 -75 and beta at 60-65. My money may not be on Fix any longer. If brewing science gurus can't get it right, where are we humble home brewers? My step mash regime seems to work and seems to work well but i wouldn't mind some clarity.

Brewing science and practice also refers to alpha in the higher range and beta in the lower.

Edited by manticle, 24 February 2012 - 05:47 PM.


#5 seamad

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Posted 24 February 2012 - 05:27 PM

In gordon strongs book:
B amylase 55-66 with best at 61-63 at pH 5.3,
A amylase best 68-72 at pH 5.1-5.9.
A amylase works over a wider range but slower than B amylase
Cheers
Sean

#6 seamad

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Posted 24 February 2012 - 05:55 PM

Just checkd out radical brewing,
Beta 60-65
Alpha 65-71
Beta breaks down starch into s mall maltose molecules( easily fermented)
Alpha breaks down starch into random sized ( less fermentable )
Looks like fix maybe incorrect

#7 MHB

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Posted 24 February 2012 - 06:01 PM

Its a typo in the Fix book; there are a couple of beauties in Brewing Science and Practice to.
The best representation I have seen is the one in German Brewing (Braukaiser.com) which illustrates the temperature and pH relationship very well. The most important thing to take from the discussion is that enzymes dont turn on and off like a light its a range and that range depends on several other variables. One of the interesting ones being Calcium, in high concentrations it protects Alpha Amylase from thermal denaturing that in some cases you can still have amylase activity into the mid 80s oC not saying that thats good or that the beer will taste better just that its interesting.
Mark
Attached File  600px_PH_and_temp_enzyme_matrix.jpg   65.51KB   98 downloads

#8 Nick JD

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Posted 24 February 2012 - 06:27 PM

Also worth considering the action the amylases have on a starch molecule.

I've always thought we'd be better off doing reverse stepping. Dough in at 72C, then after 15 minutes pour in cold water to land at 62C.

How to Brew has the same diagram, albeit easier to read - bust suggesting that if you mashed at 66.5C, you'd activate neither enzyme and convert nothing. These enzymes work at 30C, just too slowly to ward off the bacteria that are also trying to eat your carbs.

Posted Image

Edited by Nick JD, 24 February 2012 - 06:36 PM.


#9 Zebba

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Posted 24 February 2012 - 07:42 PM

I've actually thought similar to Nick and do the opposite of a standard infusion. Start high, then add more grain to drop the temp. I.e step 70, 62, 72. the idea being the first step creates a bunch of dextrins, the second turns them into maltose using the enzymes in the infused grain, and the third finished what was left in the "infusion"grain.

Disclaimer... This may be drunken rambling. I'm not a guru by any stretch, just interested

#10 Muscovy

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Posted 24 February 2012 - 08:11 PM

Also worth considering the action the amylases have on a starch molecule.

I've always thought we'd be better off doing reverse stepping. Dough in at 72C, then after 15 minutes pour in cold water to land at 62C.

How to Brew has the same diagram, albeit easier to read - bust suggesting that if you mashed at 66.5C, you'd activate neither enzyme and convert nothing. These enzymes work at 30C, just too slowly to ward off the bacteria that are also trying to eat your carbs.

Posted Image


I too have pondered the reverse step for a couple of reasons.

The milled grain would need ample time to hydrate to get those enzymes cranking though.

There are a plethora of other important enzymes that go to work during the mash as well.

Neither alpha or beta amylase are responsible for cleaving amylopectin branch points.

I have just resorted to digging out my trusty old Biochem text from my Uni days...havent located temps to support Manticles query yet but concur that fix has got it wrong.

#11 MHB

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Posted 24 February 2012 - 08:23 PM

What I dont like about the diagram in how to brew is that its clearly misleading, we know we can mash at 65.5oC. Thats the problem with nice discrete borders, they make people think On/Off which isnt the case at all, whats inside the boxes might be the Optimum temp/pH but its far from the end of the story. Remember that the enzymes are there to convert starch into soluble sugars for the sprouting grains benefit not to make mashing easier; Enzymes are working at ambient temperatures (all be it slowly) and all the way up to the point where they are denatured (killed) by getting too hot.

Which leads back to the first point, if you mash in, in the +70oC range you will denature most of those useful enzymes that work best below say 65oC (give or take).
When the wort cools those enzymes are gone/dead/killed... Jesus isnt going to step in and do a Lazarus on them, and you wont have enough enzymes left to make beer, which is lets face it rather the point of the whole exercise.
Even adding more malt to lower the temperature is fraught with problems, you would still be asking a lot from the remaining enzymes and unless you are very lucky the results would be to say the least unpredictable you might even need to resort to diluting the wort and adding sugar to stop the beer being the consistency of glue you might even start to acquire silly notions like adding sugar improves beer.
Mark

#12 manticle

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Posted 24 February 2012 - 08:27 PM

It's a typo in the Fix book; there are a couple of beauties in Brewing Science and Practice to.
The best representation I have seen is the one in German Brewing (Braukaiser.com) which illustrates the temperature and pH relationship very well. The most important thing to take from the discussion is that enzymes don't turn on and off like a light it's a range and that range depends on several other variables. One of the interesting ones being Calcium, in high concentrations it protects Alpha Amylase from thermal denaturing that in some cases you can still have amylase activity into the mid 80's oC not saying that that's good or that the beer will taste better just that its interesting.
Mark
Attached File  600px_PH_and_temp_enzyme_matrix.jpg   65.51KB   98 downloads



So it's simply a misplaced alpha sign? The ranges are a bit all over the place but that I can accept as they are presumably a combo af actual ranges and their extremities and the optimal range (which is influenced by factors other than just temp) might be a point of opinion or contention.

Basically my concern is that I'm not wasting my time by mashing at 63 then 68 to get a well attenuated beer with body. My experiential results suggest I'm not wasting my time at all but I incorporate a 72 rest for glyco proteins as well. A lot of people will skip the high 60s and go straight for 63/72.

For me it's not a big drama to do all 3 but if I recommend the regime to someone else, it's nice to have something more than 'works for me'. It's also nice to think I'm not being led astray by brewing texts with a pedigree or if I am, when I am.

@Nick: my main concern with that idea is denaturing the enzyme that works at lower temps by starting at too high a temp. I'd rather ramp up than ramp down but am interested to know if that's a furphy.

Edited by manticle, 24 February 2012 - 08:28 PM.


#13 Muscovy

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Posted 24 February 2012 - 08:31 PM

All valid.
What about if you mashed in at low temp (avoid the glue, but swell your starch granules), first step raise temp constantly to as high as you can before denaturing enzymes, and then step back through the optimal ranges?
I realise it's all completely hyperthetical, but thats what i have been pondering.

#14 manticle

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Posted 24 February 2012 - 08:34 PM

I don't understand what the advantage of reverse mashing is meant to give. Even if enzymes don't denature from too high temp (which they will) why mash in high then drop as opposed to mash in low and raise?

Edited by manticle, 24 February 2012 - 08:38 PM.


#15 Muscovy

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Posted 24 February 2012 - 08:44 PM

I don't understand what the advantage of reverese mashing is meant to give. Even if enzymes don't denature from too high temp (which they will) why mash in high then drop as opposed to mash in low and raise?



My thinking is along the lines of complete starch hydration for improved enzyme penetration (reduced mash time) and in particular keeping right away from tannin extraction that is occurring in the late 70 degrees...

The main reason is that my set-up is very average and i would find it easier to step in reverse at this point
But mostly because i am a nerd and I like to rationalise different approaches to those offered by people who publish books..however ill informed i may be.


I wonder if anyone has tried it?

#16 Thirsty Boy

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Posted 24 February 2012 - 10:17 PM

a Sake mash is conducted at entirely temperatures between 10 & 20 degrees C and still manages to very nicely activate the Alpha amylase enzyme that is predominant in Sake fermentations. I watched a whole pot of rice turn to mush and sugar all at about 25C in the last day or so... it just took 48hrs instead of 1.

The other variable that people forget is time - ALL the enzymes are active at all the temps... its just a matter of how hard they are going, how fast they die and how long you give them.

All so much more complicated than the simple texts would have it -- and all so irrelevant to practical brewing.

Low 60's = target beta = fermentable
High 60's = target alpha = not so fermentable

and some moderately sensible juggling between the two is really all thats required unless you have the desperate urge to geek out over muinutia... like me.

Edited by Thirsty Boy, 24 February 2012 - 10:21 PM.


#17 Nick JD

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Posted 24 February 2012 - 11:05 PM

These enzymes work at 30C, just too slowly to ward off the bacteria that are also trying to eat your carbs.


For Thirsty's Sake.

#18 Muscovy

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Posted 25 February 2012 - 08:19 AM

a Sake mash is conducted at entirely temperatures between 10 & 20 degrees C and still manages to very nicely activate the Alpha amylase enzyme that is predominant in Sake fermentations. I watched a whole pot of rice turn to mush and sugar all at about 25C in the last day or so... it just took 48hrs instead of 1.

The other variable that people forget is time - ALL the enzymes are active at all the temps... its just a matter of how hard they are going, how fast they die and how long you give them.

All so much more complicated than the simple texts would have it -- and all so irrelevant to practical brewing.

Low 60's = target beta = fermentable
High 60's = target alpha = not so fermentable

and some moderately sensible juggling between the two is really all thats required unless you have the desperate urge to geek out over muinutia... like me.



Your right.. the brew publications don't even scratch the surface as to how complicated/interesting it really is, albeit irrelevent to practical brewing.

Having said that, just looking into cofacters and coenzymes and the impact one could have on stabilising alpha amylases and the likes is very interesting..who knows, could even create a simpler mash process in reverse with amazing outcomes...

Perhaps some additional research for people playing with water chemistry..or not

MHB eluded to the benefits of Calcium ions as a cofacter to stabilising enzymes, and this is just the tip of the iceberg.

oops, starting to geek out!

#19 manticle

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Posted 25 February 2012 - 08:27 AM

unless you have the desperate urge to geek out over muinutia... like me.


That's pretty much it. I understand the basics of how it works in relation to my beer and am certainly comfortable with the results I'm getting but yes a level of geeking out is interesting.

So to summarise:

Temperature, time and pH all combine to give certain enzymes present in malted barley an optimum range.

Within usual mash pH ranges and within certain time-frames, beta amylase works roughly somewhere in the low to mid 60s to produce maltose from starches in barley? It will work higher but less effectively and lower but less effectively? Or will it still work as effectively higher but the alpha amylase influence will essentially 'compete' so its influence on the end result is less obvious?

In similar conditions, alpha amylase works roughly in the region of 65 -70 but will still work above 70, with both becoming denatured around 77-78?

Glycoproteins are formed between 70 and 72 (optimally)?

The amylase enzymes enzymes will perform, sluggishly at temperatures way below this, as will many others?

Fix (or the editors) have mixed up the alpha and beta in both their description and table but have given optimal ranges for mashing in shorter time frames to attain a certain wort quality? There is variation between texts as to what is considered 'optimum'

There is still a point doing a 3 stepped mash from 62-68-72 rather than just a two stepped from 63-70?

Cheers

#20 Muscovy

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Posted 25 February 2012 - 08:42 AM

Thats loosely my understanding.
Was reading about enzyme denaturation last night, and my biochem text states that all enzymes in general start to denature above 60 degrees, hence their activity starts to taper off.
As long as the substrate is freely available (hydrated starch) and optimal pH is available, conversion will be complete well before denaturation.
Certain metal ions support enzyme stability, other metal ions facilitate better enzyme activity, but may speed denaturation.
If you are going to enough trouble (geeking out) to play with water chemistry, then knowing how it is impacting enzyme kinetics may be a worthy investigation.
It's on my R-2-To-Do list....after i get my set-up sorted for better step mashing control. (Not in reverse of course)

Apologies for my soap box performance, just wanted to add to the discussion.
Fix has it wrong