One thing I don't get. Diff mash temps and conversion time

I bet this has a simple answer to it, but I don't get it.

People say that conversion is done fast, like 20-30 minutes.

Then why raise the temp from beta to alpha rest after 40 minutes, wouldn't the betas have converted it all by that time?

My understanding is that it's not that black-and-white. Some grains convert more quickly than others, and temperature plays a factor in the speed of conversion as well. I would love to find a really in-depth study on mash chemistry. I'm sure it exists, but it's probably in a $300 text book somewhere, and not in a $30 Brewers Association publication.

Smellyglove said:

I bet this has a simple answer to it, but I don't get it.

People say that conversion is done fast, like 20-30 minutes.

Then why raise the temp from beta to alpha rest after 40 minutes, wouldn't the betas have converted it all by that time?

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Enymes are temp dependent. While not shut down completely at temps below prime, they aren't exactly excited to be there. Above a certain temp and they do shut down completely.

Beena veruy long time since I have read into all this and , IIRC, betas focus on long chains, alpha focus on short chains. The dual approach is geared toward reduction of haze forming proteins.

TheZymurgist said:

My understanding is that it's not that black-and-white. Some grains convert more quickly than others, and temperature plays a factor in the speed of conversion as well. I would love to find a really in-depth study on mash chemistry. I'm sure it exists, but it's probably in a $300 text book somewhere, and not in a $30 Brewers Association publication.

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I think I still have a pdf copy of one of the older brewing textbooks. Way over my head but an interesting read.

The 10 minute mash crowd is crushing their grain extremely fine. This greatly speeds up conversion time, but by compressing it into a short span of time; you make it more difficult to control the enzymatic activity.

With a courser crush, husks intact and chunky starchy endosperm, conversion is slower and you have more opportunity to successfully manipulate your mash with temperature steps.

After Smelly posted this I went in search of a document that discussed 'step mash.' I thought I had bookmarked it but I guess not :-( Anyway, while single infusion mash is probably most used by homebrewers, the author suggested that he always uses a step mash when brewing Belgian beers. His article detailed the differing enzymatic activity that takes place at different rests. I have read similar stuff before, but this author dumbed it down for me. In the meantime, here is a different article with much the same data ... http://byo.com/mashing/item/1415-step-mashing-techniques

I hope it helps to more fully understand how the grist responds to different temps.

soccerdad said:

After Smelly posted this I went in search of a document that discussed 'step mash.' I thought I had bookmarked it but I guess not :-( Anyway, while single infusion mash is probably most used by homebrewers, the author suggested that he always uses a step mash when brewing Belgian beers. His article detailed the differing enzymatic activity that takes place at different rests. I have read similar stuff before, but this author dumbed it down for me. In the meantime, here is a different article with much the same data ... http://byo.com/mashing/item/1415-step-mashing-techniques

I hope it helps to more fully understand how the grist responds to different temps.

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That's a good article. One thing I didn't catch in the original post is that the mash usually isn't raised from beta to alpha rests, since the active temp ranges for both overlap. The purpose of a step mash is to perform a specific function, such as the break down of beta glucanase, before conversion begins. But, even if you did, the way I understand it is that beta amylase isn't able to convert all of the starches (since it only works on the ends of the starch chains) so that if you performed a rest at 140º, since there would presumably be no alpha amylase activity at that rest, there would still be some starch left over if you were to raise the temp to 160º.

I would think the beta eat up all the starches as well. I posted a similar question here once and didn't get a really good answer.

Certainly dropping the temperature would allow the beta to finish what the alpha started, but I am perplexed why people think the opposite would happen. My only guess would come down to time. That since the beta work much slower that they don't finish eating and you raise the temp to alpha temps for a quick finish of the starches.



Also interesting that professionals talk about using iodine to test conversion. How come they just don't use gravity readings?

grathan said:

I would think the beta eat up all the starches as well. I posted a similar question here once and didn't get a really good answer.

Certainly dropping the temperature would allow the beta to finish what the alpha started, but I am perplexed why people think the opposite would happen. My only guess would come down to time. That since the beta work much slower that they don't finish eating and you raise the temp to alpha temps for a quick finish of the starches.



Also interesting that professionals talk about using iodine to test conversion. How come they just don't use gravity readings?

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My understanding, from what I've read, is that beta amylase only works on the ends of the starch chains, and from that I infer that it is unable to completely break down all of the starch.

Ahh neat. seems I have been understanding things backwards.

So the Beta are slower and less effective. So I wonder why bother with lower mash temps at all if the alpha can do it all? As an infusion masher this would be ideal to just have a single mash temperature. Closer to the upper side of things in the case of missing a few degrees low.

No betas break down the starch much more systematically and alphas are more unpredictable

Beta= surgeon enzyme.. higher fermentability due to the "surgeon" enzyme shearing the chain more precisely into maltose sugars takes longer

alpha= edward scissor hands enzyme.. mixed up fermentables some dextrins and some maltose etc

grathan said:

Ahh neat. seems I have been understanding things backwards.

So the Beta are slower and less effective. So I wonder why bother with lower mash temps at all if the alpha can do it all? As an infusion masher this would be ideal to just have a single mash temperature. Closer to the upper side of things in the case of missing a few degrees low.

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I thought Alpha can't do it all, just making big sugars; Beta is needed to make the maltose or smaller sugars. Trouble is you can't go backwards because I thought the temps denatured (destroying) the Betas in the higher Alpha temp ranges.

ABVIBUSRM said:

Beta= surgeon enzyme.. higher fermentability due to the "surgeon" enzyme shearing the chain more precisely into maltose sugars takes longer

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this is from How to Brew though...

However, a beta-optimum wort is not a very fermentable wort, leaving a lot of amylopectin starch unconverted; alpha amylase is needed to break up the larger chains so beta can work on them.

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grathan said:

this is from How to Brew though...
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been brewing 10 years and i learned that beta makes more maltose the prefered fermentable sugar and alpha makes less fermentable..thats whats great about this hobby you keep on learning thanks for posting that just learned

i got this from BYO

"The two most important enzymes are alpha-amylase and beta-amylase. Alpha- amylase randomly breaks the long chains of starch molecules into smaller pieces. Beta-amylase works on the ends of the pieces and produces maltose, an easily fermentable disaccharide (sugar molecule in two parts), and so-called "beta limit dextrins." The degree of complexity of the sugars is what determines those that can be metabolized by the yeast, thus contributing to fermentability, and those that will remain in the finished beer."

You may sense a general trend emerging: lower mash temperatures favor beta-amylase, which results in higher fermentability, while higher temperatures favor alpha-amylase, resulting in less fermentable wort. But the starches must be gelatinized (and beta-amylase activity is partially dependent on alpha-amylase activity). Accordingly, there is a minimum temperature of about 148 °F (64 °C) at which gelatinization has occurred and alpha-amylase becomes sufficiently active. Likewise, beyond a maximum temperature of around 158 °F (70 °C), neither enzyme is effective for very long.

So it sounds like as long as your hitting 148* there is sufficient alpha activity even though it favors a much higher temperature. Especially given the fact that most people tend to mash for at least an hour.


And back to the OP's question it still seems rather confusing why people step up the temperature to finish off a mash rather than let it drop....

grathan said:

So it sounds like as long as your hitting 148* there is sufficient alpha activity even though it favors a much higher temperature. Especially given the fact that most people tend to mash for at least an hour.


And back to the OP's question it still seems rather confusing why people step up the temperature to finish off a mash rather than let it drop....

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Because you don't step from beta amylase conversion to alpha amylase conversion. That's the key. You step from beta-glucanase step (between 112º and 120º, formerly known as protein rest) to beta/alpha amylase conversion. Look at any step mash schedule. You're not going from 145º to 158º, you're going from a much lower temp to a starch conversion temp. That's what I failed to recognize when the OP first asked the question.

I'm pretty sure that I've read a few times that people step from beta to alpha temps.

In this wiki it is referred to as a "conversion stand" rest.
http://en.wikibooks.org/wiki/Brewing/Mashing

http://books.google.com/books?id=cr...wAg#v=onepage&q=conversion stand mash&f=false


Actually the 2nd link seems to answer all of the questions I've had in this thread.

The Alpha create too many non fermentable A-limit dextrins if too prominent in the mash. So for higher fermentability the lower mash temp is good, but no too low because it is believed that Alpha Enzymes help make the starch soluable.

A mash too low in Alpha enzyme will also have too many branched starch chains as described in How to Brew.

So raising the temperature for Alpha rest towards the end of conversion breaks down the multi- strand starches the Beta could not get, while not creating too many non-fermentables which would happen if they got to pig out too early on in the mash.

So basically going from low end beta to high end beta/mid alpha makes the alphas chop up some ends for betas to feed on, should make a higher fermentable wort?

The most fermentable would be starting in a neutral spot 152* and letting the enzymes work at the same time. Assuming a standardized mash duration. But yeah, you got it.

The trick with raising the temperature is for mash conversion% percentage. Something that is different from "fermentability". People don't talk much about mash OG before sparging on this forum, but it comes into play more-so with 20 minute mashes.

But, everybody knows that a lower mash temp gives you a lower FG..?

There are a couple misperceptions in this thread. Conversion does not happen in 20 to 30 minutes, it happens in 2 to 3 minutes as evidenced by an iodine test but this fast conversion depends on a very fine grind and it may happen even faster if ground to flour. The reason that mashes take longer is the need for the grain to wet through, with larger particle taking longer. I think that this is why BIAB brewers end up with a more fermentible wort. Beta amylase is quickly denatured at higher temperatures and with larger particles you denature some of these before the enzyme gets a chance to work so you get more alpha amylase activity and less beta amylase so your wort becomes less fermentable. With the small particles the grains quickly get wet through, the two enzymes work at the same time and before the heat denatures the beta amylase, it has done its work. With that in mind, controlling the fermentability by changing temperatures becomes nearly impossible.

From the single test batch I did I cannot draw firm conclusions but I used a refractometer to measure the sugars in the wort at short intervals. Iodine would show conversion in under 5 minutes but the gravity of the wort and therefor the sugars kept increasing up to about the 30 minute mark. More testing needs to be done on this aspect.

Smellyglove said:

But, everybody knows that a lower mash temp gives you a lower FG..?

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Sometimes what 'everybody knows" is wrong or maybe right but for the wrong reasons.

I've never had any luck with iodine. I do plan to start using a refractometer on the mash though.

Also. In how to brew Palmer says that betas will denature above 65c. So I don't get how the alphas at 72 can chop up more food for the betas at 72.

“Beta is Below and Bites” is a handy pneumonic to remember that Beta Amylase works at lower temperatures and bites off 2-chain sugars from the end. “Alpha is Above” because it is active at higher temperature. Although the optimal temperature of Alpha Amylase is well above the denaturing temperature of Beta Amylase, some activity does occur even in the 150 temperature range. This enables the brewer to adjust a single-mash temperature between 146-154 and get some combination of both enzymes acting. The higher temperature will produce more dextrins and be sweeter, whereas the lower temperature will produce more maltose which is fermentable. The balance of this temperature is critical to producing the proper mash efficiency.

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"Temperature Range" listed is for optimal conversion.

Smellyglove said:

Also. In how to brew Palmer says that betas will denature above 65c. So I don't get how the alphas at 72 can chop up more food for the betas at 72.

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It's a rate question. Denaturing is not instant, so the beta will keep working for some time after the temps go above minimum for denaturing to begin. Rule of thumb for many organic reactions is that the rate of reaction approx. doubles for each 10 C (18 F) increase in temperature.

Brew on

Aight. Thanks.