Do higher mashing temps override lower mashing temps?

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beervoid

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Hello HBT,

I've been wondering about this for a while.

If I mashed 60 minutes at 145f for a high fermentable wort and after 60 minutes I decide to step up the temperature to 158f because I want a bigger body and leave that for 60 minutes.

Does the higher temp cancel out the lower temp? Do they balance out?
Do I get the same wort as mashing from the start with 158f?

Cheers!
 

dmtaylor

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If you mash two hours, you're going to have a very very dry beer. Mash TIME matters a whole lot more than temperature. Temperature is still important, but I would say if you mash for too much TIME, this overrides any extra steps you take at different temps during the mash. Most of the conversion happens in the first 20-30 minutes. Any mash time longer than that doesn't add body at all but just makes the beer more fermentable, drying it out all the more.
 

Robert65

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Dave's right. Temperature does control fermentability, but at any given mash temperature, the longer you hold it, the more fermentable the wort will be, relative to a mash held for a shorter time at the same temperature. This is basically because all the enzymes are working at all temperatures, it's just that some work a little better at certain temperature. If you're interested, good mash program to get a balance of good fermentability combined with good mouthfeel and foam qualities is 30 minutes in the 145-147F range (beta amylase,) 30 minutes at 160-163F (alpha amylase,) and 10-15 minutes at 170-172F (glycoprotein synthesis.) (In German this is called Hochkurzmaischverfahren, meaning "high [temperature,] short mash program," and is the commercial standard.) There's more than you wanted to know.
 

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Dave's right. Temperature does control fermentability, but at any given mash temperature, the longer you hold it, the more fermentable the wort will be, relative to a mash held for a shorter time at the same temperature. This is basically because all the enzymes are working at all temperatures, it's just that some work a little better at certain temperature. If you're interested, good mash program to get a balance of good fermentability combined with good mouthfeel and foam qualities is 30 minutes in the 145-147F range (beta amylase,) 30 minutes at 160-163F (alpha amylase,) and 10-15 minutes at 170-172F (glycoprotein synthesis.) (In German this is called Hochkurzmaischverfahren, meaning "high [temperature,] short mash program," and is the commercial standard.) There's more than you wanted to know.
that is a high temp for mashing...When I was single decoction mashing I would hit 150-154 for the duration , usually an hour. Once I started step mashing I do 130ish, 140ish then low 150ish . Im reading a passage in Ray Daniels Designing Great Beers right now that I obviously passed over before . I'm actually having a hard time deciphering what it means . maybe you can help .
It says (for triple decoction)under Weissbier Brewing Technique(pg 340)-
"Hot water is added to raise the temperature to 95*F ,mix for 5 minutes"
"Thick mash is pulled for decoction and boiled for 45 minutes. When added back ,this decoction raises the main mash to 113*F .Mixed 2 minutes"

again for a temp of 136*F.

It then says
"Pull lauter mash (liquid ,no grain) and boil for 15 minutes .When added back to main mash ,this decoction raised main mash to 160*F Mixed for 5 minutes . Rest for one hour."

when it says a thick mash or the lauter mash is pulled for decoction, is it saying basically to take the wort off at that point and boil it then add it back to the mash tun in order to raise the specific temperature? Or is it boilng the wort and grain together at that point ?
If so, until now I've just been adding more hotter water until I reach the temps (step mashing) .If I understand this right, its kind of doing the boil along with the mash process and in doing so , concentrating the fermentable sugars and raising the gravity.
 
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beervoid

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Thanks for the replies.
So following that logic the first 30minutes are crucial for and the avarage temperature during this define how fermentable your wort will be?
 

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Thanks for the replies.
So following that logic the first 30minutes are crucial for and the avarage temperature during this define how fermentable your wort will be?
The first rest is the beta amylase rest. Beta chops the starch in really small pieces which are highly fermentable.

The second step is the alpha amylase step, alpha amylase chops starch into bigger pieces, some of them being unfermentable for most yeasts.

Beta amylase degenerates quickly at alpha temperature, this is the reason why alpha is working almost exclusively after a short time at it's optimum temperature range.

The downside is, if the beta already went through all the available starches during the first rest, the alpha will have nothing to chop into bigger pieces as the beta already chopped everything into smaller pieces.

Alpha won't make short pieces longer, alpha can only turn long starch molecules into complex sugars. If there are no starches left, there won't be more complex sugars through promoting alpha activity.
 

dmtaylor

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Thanks for the replies.
So following that logic the first 30minutes are crucial for and the avarage temperature during this define how fermentable your wort will be?
That's not far from the truth. But you still need to consider total time in the mash. If you want a full body, then quit mashing altogether at 20-30 minutes, mash out right away. If you want a very dry beer, mash for 90 minutes or more. If you want something in between, mash for a more reasonable 45-60 minutes. Personally I've been mashing for 45 minutes for the past >100 batches. It's a nice middle ground for me and my system.
 

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Interesting discussion. Best info. I've gotten in ages! And yes, I'm sure I've read it somewhere/sometime (I have over 20 books on brewing) but Dave and Robert and Miraculix laid it out so plainly. Should make this a sticky so I can find it again and refer to it- especially Dave's Hochkurzmarchverfahren, which is certainly a mouthful!
 

bracconiere

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The first rest is the beta amylase rest. Beta chops the starch in really small pieces which are highly fermentable.

The second step is the alpha amylase step, alpha amylase chops starch into bigger pieces, some of them being unfermentable for most yeasts.

Beta amylase degenerates quickly at alpha temperature, this is the reason why alpha is working almost exclusively after a short time at it's optimum temperature range.

The downside is, if the beta already went through all the available starches during the first rest, the alpha will have nothing to chop into bigger pieces as the beta already chopped everything into smaller pieces.

Alpha won't make short pieces longer, alpha can only turn long starch molecules into complex sugars. If there are no starches left, there won't be more complex sugars through promoting alpha activity.
+1
 

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Interesting discussion. Best info. I've gotten in ages! And yes, I'm sure I've read it somewhere/sometime (I have over 20 books on brewing) but Dave and Robert and Miraculix laid it out so plainly. Should make this a sticky so I can find it again and refer to it- especially Dave's Hochkurzmarchverfahren, which is certainly a mouthful!
Thanks.

Ok, let me ellaborate a bit further, as this was also one of the most interesting things to research about for me.

So far, we overlooked one very important factor in this game between starch/alpha/beta, which is gelatinization temperature.

Gelatinization of starch is the process in which starch is made accsessible for the enzymes. It is kind of a dissolving process in water, although it actually is a bit less than fully dissolving. Let's not dig deeper here and just stay with the fact that ungelatinized starch cannot be converted by alpha or beta amylase.

The thing with gelatinization temperature is, that it varies from grain to grain, from malt to malt and from year to year. Generally speaking, for barley the Gelatinization temperature falls comfortably into the typical mash temperature range somewhere 58C and upwards. But not every tiny bit of starch in the malt has the same gelatinization temperature, so the lower the temperature and the less the time it is held at this temperature, the more of the starch can still be potentially ungelatinized and therefore not being able to be converted by the enzymes.

This can leave a potential of starches unconverted during a lower temperature beta rest, especially when the grain is not crushed very fine and especially when the step is short in time.

If you would make a iodin test in a low temperature beta mash after, let's say, 15 minutes, the iodine test would show negative results for starch in solution, beta is quick, it really chops down everything in solution within minutes... but, it has to be in solution or gelatinized. There might be still some starch left within the grains, which just has not been gelatinized and cannot be "seen" by the iodine test.

What happens if the temperature now is going to be raised to alpha rest temperature? Meaning usually going from 62c to 72c. On the way there, most of the beta degenerates due to the heat and only the alpha remains. Also somewhere along the temperature rise, the remaining starch might be gelatinised, due to the raised temperature and if the remaining beta does not chop these starches up before all the beta degenerates, the alpha will get hold of those starches and chop them into longer sugars, creating body and potentially residual sugars (which actually do not taste that sweet at all...).

And one more thing about synergetic effects between enzymes.

Beta kind of attacks starch molecules from the end, chopping off parts of it, wheras alpha cuts the starch molecules more in the middle, creating potentially more "ends" for the beta to work on.

A rest in between both optimum temperatures, somewhere around 65C can therefore create very fermentable wort, very fast. The beta chops everything into small pieces it can get hold of and the alpha "pre-chops" the starches for the beta to further chop them into pieces.

This goes this far, that for example in German Weissbier Brauereien, parts of the freshly doughed in wort is extracted, chilled and set aside. Then the mash is done normally via Hochkurz and at the endpoint, where no beta is left anymore and all the starches are converted, after the second step around 72C, the wort is chilled down to beta rest again and now the previously separated part of the wort is mixed in with the wort at beta temperature. The part of the wort that has been set aside is still rich in undegenerated beta amylase and now helps to chop down the remains from the alpha step, creating a wort rich in glucose which increases ester production in German Wheatbeers.

The homebrewer can just add glucose to mimic those processes without the hustle... but somehow a lot of us Germans still think that the Reinheitsgebot is something important so they invented this workaround.

I for myself cerntainly think that the Reinheitsgebot ist purely dogmatic and unnecessary, but that is for another topic....
 
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dmtaylor

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Should make this a sticky so I can find it again and refer to it- especially Dave's Hochkurzmarchverfahren, which is certainly a mouthful!
Oh that's not my word, that's Robert's. I don't speak German and honestly have never heard that one before. Definitely cannot pronounce it! ;)

EDIT: @Miraculix is right about gelatinization too. That's an important aspect to consider. If the starches are not all adequately gelatinized because you didn’t hit the proper gelatinization temperature threshold for long enough (somewhere in the 140s for most grains), then you can still end up with starch in your wort which is not very fermentable by most commercial yeasts… though some wild organisms can eat it, which can lead to refermentation, gushers, or explosions later on if you aren’t careful, not to mention starch haze.
 
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mongoose33

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Let me extend the excellent info and discussion from @dmtaylor and @Miraculix with some recent personal experience and cogitating.

Here's the interesting thing for me: I've been wondering for a while about doughing in at strike water temps that are from 162 to 168, typical values for anyone doing either BIAB or a traditional mash tun system. In my system, I'm underletting the grain, and given the grain bill and full infusino, been doing that about 162 or so. That's a fairly high temp for Beta Amylase, and as it takes about 7 minutes for the complete underlet, that means the grain at the bottom of the mash tun is being continually bathed in 162-degree water.

That can't be doing anything for the Beta Amylase in that layer of grain. So I've been cogitating on that--am I destroying a lot of the enzymes I need by the time I get the temp down to, say, 152 for the remainder of the mash?

It dawned on me--if I'm doing a step-mash, the grain I'm underletting never sees temps higher than 149--and in the early stages of the step mash, they're lower than that. Further, the starch in the grain is going through a range of temps which (given Miraculix' comments above) should enhance gelatization, and ultimately, conversion.

But if I'm doughing in using 162-degree strike water, or, as is the case with limited strike water in anticipation of using sparge water, doughing in at 168 degrees....I have to be denaturing some, or much, of the Beta Amylase.

******

I've recently been diddling with step mashing with interesting results. My son had done some step mashing with a kolsch, starting at 125 and then going up to 149 degrees. I decided I'd play with it too, as i have a RIMS system that allows for increasing the mash temps. My first attempt ended up with the mash a little warm, at 132 degrees; I was pumping 139-degree water into the mash. Don't you just love empirical knowledge? :) But it turned out fine.

I've done two Kolsch's doing the 132 to 149 step mash. I hold at 132 for 10 minutes, then it rises to 149 over the next 15 minutes. I'm reading temps at the output side of the RIMS tube, so temps are really not rising beyond 149.

Both of those Kolsch's had the lowest final gravity I've ever seen in a beer, the one using WLP-029 at 1.007, and the one using Wyeast 2565 at 1.006. They were/are delicious, still with terrific flavor (I do a weird recipe, so it's a "flavorful" Kolsch). Though I prefer the WLP-029.

Clearly the Beta Amylase is chopping down those starch chains. I don't know what the Alpha Amylase is doing except giving the Beta Amylase more starch molecule ends to chop sugars from.

I just brewed my dark lager using the same type of step mash, though I started at 136 and then ramped to 149. It's done fermenting, and the Tilt-indicated gravity is 1.010. I use WLP-940 for this, and I've never been below 1.013 for final gravity. I was looking for a bit drier, crisper beer, and I'm hopeful that's exactly what I'm going to get.
 
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The reason im digging a bit further is because I had my last batch attenuate very low on me. 67%
I normally get around 73 to 76% attenuation.

It was a 11 gallon batch that was split to ferment with 2 yeasts. 1.070 og and I made starters of 1 liters before pitching. I highly doubt its the yeast as I used 2 different yeasts.

What was different on my other batches?

I have a recirculating setup and the recirculation was very bad, due to a kind of stuck mash.
I attempted to manually measure the temps and found I was a bit under my target temp of 152f.
I measured at lowest maybe 147 148.
This was about 10minutes in the mash.
I started heating the mash and kept track of the temps manually. Once I hit my target temp I move the temp probe around a bit I found there where different temps at different spots. Probably due to bad circulation.
I think I might have risen the temperature within 60mins to about 160f or higher.
In total I mashed at least 1h and 30mins yet I ended up with not such a great fermentability.

Perhaps it went too high too fast and killed all enzyme action?
Also the Chit Malt seems to leave less fermentable wort. My last batch with it wasnt this bad though.
 

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The Germans do have a strange obsession with taking an entire sentence and pretending it's a single noun. :D
Hahaha, yes, this is correct. Literally it translates to: High short mashing method.

But the Best one i've personally encountered was Fussbodenschleifmaschinenverleih. Floor grinding machine lending store.

Let me extend the excellent info and discussion from @dmtaylor and @Miraculix with some recent personal experience and cogitating.

Here's the interesting thing for me: I've been wondering for a while about doughing in at strike water temps that are from 162 to 168, typical values for anyone doing either BIAB or a traditional mash tun system. In my system, I'm underletting the grain, and given the grain bill and full infusino, been doing that about 162 or so. That's a fairly high temp for Beta Amylase, and as it takes about 7 minutes for the complete underlet, that means the grain at the bottom of the mash tun is being continually bathed in 162-degree water.

That can't be doing anything for the Beta Amylase in that layer of grain. So I've been cogitating on that--am I destroying a lot of the enzymes I need by the time I get the temp down to, say, 152 for the remainder of the mash?

It dawned on me--if I'm doing a step-mash, the grain I'm underletting never sees temps higher than 149--and in the early stages of the step mash, they're lower than that. Further, the starch in the grain is going through a range of temps which (given Miraculix' comments above) should enhance gelatization, and ultimately, conversion.

But if I'm doughing in using 162-degree strike water, or, as is the case with limited strike water in anticipation of using sparge water, doughing in at 168 degrees....I have to be denaturing some, or much, of the Beta Amylase.

******

I've recently been diddling with step mashing with interesting results. My son had done some step mashing with a kolsch, starting at 125 and then going up to 149 degrees. I decided I'd play with it too, as i have a RIMS system that allows for increasing the mash temps. My first attempt ended up with the mash a little warm, at 132 degrees; I was pumping 139-degree water into the mash. Don't you just love empirical knowledge? :) But it turned out fine.

I've done two Kolsch's doing the 132 to 149 step mash. I hold at 132 for 10 minutes, then it rises to 149 over the next 15 minutes. I'm reading temps at the output side of the RIMS tube, so temps are really not rising beyond 149.

Both of those Kolsch's had the lowest final gravity I've ever seen in a beer, the one using WLP-029 at 1.007, and the one using Wyeast 2565 at 1.006. They were/are delicious, still with terrific flavor (I do a weird recipe, so it's a "flavorful" Kolsch). Though I prefer the WLP-029.

Clearly the Beta Amylase is chopping down those starch chains. I don't know what the Alpha Amylase is doing except giving the Beta Amylase more starch molecule ends to chop sugars from.

I just brewed my dark lager using the same type of step mash, though I started at 136 and then ramped to 149. It's done fermenting, and the Tilt-indicated gravity is 1.010. I use WLP-940 for this, and I've never been below 1.013 for final gravity. I was looking for a bit drier, crisper beer, and I'm hopeful that's exactly what I'm going to get.
Just to be sure you didn't get me wrong, multiple temperature rests do not enhance gelatinization. The higher the temperature and the longer the grain stays at this temperature, the higher the gelatinisation. But this obviously has to be balanced with enzyme activity....
 

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Just to be sure you didn't get me wrong, multiple temperature rests do not enhance gelatinization. The higher the temperature and the longer the grain stays at this temperature, the higher the gelatinisation. But this obviously has to be balanced with enzyme activity....
Then I'm confused. (First time in almost 2 hours) :)

Here's what you said, and it resonated with me:

The thing with gelatinization temperature is, that it varies from grain to grain, from malt to malt and from year to year. Generally speaking, for barley the Gelatinization temperature falls comfortably into the typical mash temperature range somewhere 58C and upwards. But not every tiny bit of starch in the malt has the same gelatinization temperature, so the lower the temperature and the less the time it is held at this temperature, the more of the starch can still be potentially ungelatinized and therefore not being able to be converted by the enzymes.
So, as gelatinization varies grain to grain, malt to malt, and year to year, am I not , with a step-mash, increasing the chances I hit a temp where that can occur, and thus, have better gelatinization and then conversion?
 

Robert65

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Also note that conversion does take place before full gelatinization occurs. Some of the starch is already available, so amylases are already going to town even if you mash in at low "protein rest" temperatures. You just cannot readily access ALL of the starch.
 

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5 minutes. Remember that.

From BYO article

"Beta amylase is active between 131° and 149° F. But like all enzymes, its activity reaches a peak, declines, and then drops precipitously as temperature increases. The rate is also dependent on the amount of enzyme present. It takes time for all of the enzyme to be destroyed, but what is still intact works very quickly. So as the mash temperature approaches 149° F, beta amylase is operating at its fastest rate but it is also being denatured.

This may seem trivial, but at these higher temperatures the denaturation is so rapid that the enzyme is mostly gone in less than 5 minutes. Also, in a homebrewer’s mash tun, where the grain may be poured into very hot water, the exposure to very high heat for the few seconds before the mixture becomes homogenous may work to destroy the fragile enzymes."
 

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The reason im digging a bit further is because I had my last batch attenuate very low on me. 67%
I normally get around 73 to 76% attenuation.

It was a 11 gallon batch that was split to ferment with 2 yeasts. 1.070 og and I made starters of 1 liters before pitching. I highly doubt its the yeast as I used 2 different yeasts.
What yeasts did you use and how old were they?
Do you use a stir plate?

I recall hearing Jamil on the brewing network brew strong show saying too small of a starter can be detrimental to the yeast health.

Under pitching can give low attenuation.

If you have a very fresh pack of yeast (100Bcells) a 1 liter starter would give 238Bcells and leave you a bit light on the recommended 266Bcells for 5.5gal of 1070 wort. If was a few months old you would be further way from the recommended amount.
 

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There used to be a lot of very specific, supposed information in brewing texts on temperature and pH optima for different enzymes and also the conditions for their denaturing. Most of this seems to have been proven oversimplified and obsolete. First consider this. Nature intended these enzymes all to be active in a seed stuck in cold dirt. So they are all active well below their supposed optimal ranges. On the flipside, the more current literature indicates that enzymes reach peak activity at the top of and above what used to be considered their useful range, and that it takes hours, not minutes, to fully denature enzymes at temperatures above their optimum but still within normal mashing conditions. So in practical terms, they are never denatured in the mash tun. In practice, enzymes are only fully denatured in the boil. In short, by adjusting temperature programs and other conditions, we can FAVOR one enzyme, but not completely suppress the activity of another.
 

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Then I'm confused. (First time in almost 2 hours) :)

Here's what you said, and it resonated with me:



So, as gelatinization varies grain to grain, malt to malt, and year to year, am I not , with a step-mash, increasing the chances I hit a temp where that can occur, and thus, have better gelatinization and then conversion?
Ahhh, there is the misunderstanding!

Gelatinization temperature is to be understood as "minimum temperature at which the starch gelatinizes", meaning higher temperatures than the gelatinization temperature will speed things up.
 

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This goes this far, that for example in German Weissbier Brauereien, parts of the freshly doughed in wort is extracted, chilled and set aside. Then the mash is done normally via Hochkurz and at the endpoint, where no beta is left anymore and all the starches are converted, after the second step around 72C, the wort is chilled down to beta rest again and now the previously separated part of the wort is mixed in with the wort at beta temperature. The part of the wort that has been set aside is still rich in undegenerated beta amylase and now helps to chop down the remains from the alpha step, creating a wort rich in glucose which increases ester production in German Wheatbeers.
How long is the rest after the 2nd fresh wort is added back in? Something like 15 min at 145F? Then are any other rests performed? Like a mash out etc... I would like to try this. Thanks.
 

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How long is the rest after the 2nd fresh wort is added back in? Something like 15 min at 145F? Then are any other rests performed? Like a mash out etc... I would like to try this. Thanks.
I have only limited lnowledge about this, only tried it once myself in a modified way, I added very very highly diastetic malt to the mash, after cooling it down to beta rest temperatures again. It kind of worked.

I think it is something along the line of mash in at 62C, removing 1/4 to 1/3 of the liquid after a few minutes and chilling it,

then with the rest 30 min 62C, 30 min 72C, cooling down to 62C and bringing back the 1/3 that was removed before and keeping it for 30 min at 62C.

After this, mashout at 77C for 20 minutes for glycoproteinproduction (never skip this step, no matter what).

It is Called Herrmann Verfahren or Herrmann Method. Maybe you can find english literature that goes more into detail.
 

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too small of a starter can be detrimental to the yeast health.

Under pitching can give low attenuation.
I've heard this before, and I do NOT agree with it at all. If you underpitch, I think you'll either get the yeast to multiply to the point where they'll attenuate normally.... or they won't really take off well at all. So, either you'll have normal attenuation by the intended yeast, or zero attenuation, or variable attenuation due to no competition with contamination by wild organisms. It's one of the three things will happen.
 

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I have only limited lnowledge about this, only tried it once myself in a modified way, I added very very highly diastetic malt to the mash, after cooling it down to beta rest temperatures again. It kind of worked.

I think it is something along the line of mash in at 62C, removing 1/4 to 1/3 of the liquid after a few minutes and chilling it,

then with the rest 30 min 62C, 30 min 72C, cooling down to 62C and bringing back the 1/3 that was removed before and keeping it for 30 min at 62C.

After this, mashout at 77C for 20 minutes for glycoproteinproduction (never skip this step, no matter what).

It is Called Herrmann Verfahren or Herrmann Method. Maybe you can find english literature that goes more into detail.
Thanks. I often do an acid rest for hefeweizen so I was thinking to pull the extra wort out after or after a short protein rest. Either way before getting to anything above 131F. It would be slick to get the temps right so just the addition would bring the entire mash down to 144F from the 161F rest.

I have been hearing more and more about the importance of a prolonged mashout rest. Anything further to add about its importance? Seems like head retention is a major benefactor. Thanks.
 

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I have only limited lnowledge about this, only tried it once myself in a modified way, I added very very highly diastetic malt to the mash, after cooling it down to beta rest temperatures again. It kind of worked.

I think it is something along the line of mash in at 62C, removing 1/4 to 1/3 of the liquid after a few minutes and chilling it,

then with the rest 30 min 62C, 30 min 72C, cooling down to 62C and bringing back the 1/3 that was removed before and keeping it for 30 min at 62C.

After this, mashout at 77C for 20 minutes for glycoproteinproduction (never skip this step, no matter what).

It is Called Herrmann Verfahren or Herrmann Method. Maybe you can find english literature that goes more into detail.
If you have access to Kunze's textbook (Technology Brewing and Malting) it is referred to in ch. 3 as the Maltase Process, as it is actually temperature sensitive maltase which is being introduced to the gelatinized mash. He references mashing in the larger portion of the mash at 62C, reaching 70C after 40 minutes, then adding a separate cold mash to bring the whole down to 45C, resting at least 40 minutes, then proceeding as normal through the rests up to mash off. The purpose is apparently to maximize glucose content in the wort, which with a Hefeweizen yeast results in a massive increase in the banana esters (ethel and isoamyl acetates) and reduction in acetaldehyde.
 

Bassman2003

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Thanks Robert. So in your example, you would be doing higher rests before the lower rests, then adding more malt/wort and doing the entire mash process again. Most of the wort would have beta denatured before the 2nd run. I was in a thread with Miraculix where it was discussed to add up to 20% DME or glucose for a cheat instead of the mash gymnastics. I have yet to try it but it is on my list of things to do.
 

mongoose33

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There used to be a lot of very specific, supposed information in brewing texts on temperature and pH optima for different enzymes and also the conditions for their denaturing. Most of this seems to have been proven oversimplified and obsolete. First consider this. Nature intended these enzymes all to be active in a seed stuck in cold dirt. So they are all active well below their supposed optimal ranges. On the flipside, the more current literature indicates that enzymes reach peak activity at the top of and above what used to be considered their useful range, and that it takes hours, not minutes, to fully denature enzymes at temperatures above their optimum but still within normal mashing conditions. So in practical terms, they are never denatured in the mash tun. In practice, enzymes are only fully denatured in the boil. In short, by adjusting temperature programs and other conditions, we can FAVOR one enzyme, but not completely suppress the activity of another.
This is not to get into a pi**ing contest, but rather to grow the knowledge base here. If you have some sources or links to the above, I'd like to consult them. You seem to know what you're talking about.

What you said is at odds with what I believed, and when that happens, I have to reconcile the disagreement. So I did some checking online and ran across this at BYO:

[I'm breaking it into smaller chunks, though in the original it's one long paragraph)

In the brewing literature, the optimal temperature ranges for various enzymes are given. (For a summary, see Table 2.) For advanced brewers, it is important to understand what these mean. Enzymes are simple “machines” that work solely due to their shape. In solution, if they happen to bump into their substrate(s), they catalyze a chemical reaction.

As an enzyme solution is heated, the rate of reaction increases as the time it takes for enzymes to randomly bump into substrate molecules is decreased because the individual molecules are moving faster through the solution. Enzymes are active at all temperatures between the freezing point of a solution and the temperature at which the enzyme denatures.

When the temperature range for a given enzyme is stated in the brewing literature, it is the range of temperatures that result in good brewhouse performance for that enzyme. It does not mean that enzyme is inactive outside of that range. All brewing enzymes are active below their stated range. However, at lower temperatures, they are working more slowly.

The top end of an enzyme’s range is determined by the enzyme’s activity and denaturation point. Heating a step mash over the top end of an enzyme’s range does not cause that enzyme to stop working instantly. It takes time for enzymes to denature.

In some cases, enzymes will actually denature within their stated range. For example, at 149 °F (65 °C), beta-amylase is denatured within 40–60 minutes and alpha-amylase activity will cease after 2 hours at 153 °F (67 °C). The point is that, by changing mash temperatures, you are not cleanly switching enzymes on and off. Due to their simple mechanism of action, your control over them is much more “squishy.”


What they're suggesting here is that the enzymes do in fact stop within a relatively normal amount of time. However, what they do not say is where the enzymes break down and how fast that denaturing occurs at that temperature.

@balrog said the same thing I've been concerned about: when I dump crushed grain into 168-degree water, what's happening to those enzymes? Surely some must be denatured by the temps, and perhaps what we're seeing is that only part of the enzymes are being denatured. The enzymes in the first grain stirred into the strike water are probably hurting, but that grain is also lowering the temp of the strike water so later enzymes aren't under quite the attack from temps as the initial ones.

And I'm presuming that since most modern grain is well-modified and has significant diastatic power, therefore (I'm proposing/guessing here) even though some of the enzymes are denatured initially, there are enough left over to do the job.

If this strike water denaturization thing was a huge problem, people wouldn't be able to make beer. Yet they are, doing what has been done for a long, long time.

What I would love to know is at what temps the denaturing occurs most rapidly, given that (if you believe it) the BYO article says they're denaturing even in their lower ranges.
 

mongoose33

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I've heard this before, and I do NOT agree with it at all. If you underpitch, I think you'll either get the yeast to multiply to the point where they'll attenuate normally.... or they won't really take off well at all. So, either you'll have normal attenuation by the intended yeast, or zero attenuation, or variable attenuation due to no competition with contamination by wild organisms. It's one of the three things will happen.
I attended the BYO Brewing boot camp in Asheville in March; I attended two yeast workshops, one taught by Chris White (i.e., the guy from White Labs), the other a hands-on lab exercise in dealing with yeast.

We were talking during the workshop about starters and pitching. He noted, much to my son's and my surprise, that he'd just pitch a tube of his White Labs yeast (after warming) into the wort, no starter at all. He might do a starter if a cold fermentation was called for (lager), or simply pitch two tubes, but we were shocked when we heard this.

That would sound like an underpitch. Naturally my son decided this needed a test, so since March, he's been pitching with no starters. As far as he can tell, it's made no difference.

I did the same thing with my Kolsch; just pitched the WLP-029 direct, no starter, said a few prayers to the brewing gods, and lo and behold, it was a stunning beer. I had it kegged and carbonated and was serving it at the local homebrew group 11 days after pitching. I'm not kidding. Nobody believed me at first, but it was a terrific beer.

No evidence the apparent "underpitch" had any deleterious effects.

****

With lagers being fermented at 50, I'll do a starter, but I'm oxygenating the starter wort, adding a pinch of yeast nutrient, and pitching it at or around 17 hours after I put it on the stir plate. I pitch the whole thing (no crashing, no decanting) at about 70 degrees, let the wort sit at that temp for about 6 hours, then begin to drop it to 50. That's lag phase, the yeast are still reproducing, and there are no off-flavors produced that are apparent to me or anyone else who's had it.

By most published info, that's an underpitch, maybe a serious one.

The point, long-winded though it may be, is that I agree--I think most of the concern about pitch rates in home brewing is overblown, and the yeast will manage. Gross underpitches, it's a problem, because the oxygen will disappear; overpitches, there are also issues.
 

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I've heard this before, and I do NOT agree with it at all. If you underpitch, I think you'll either get the yeast to multiply to the point where they'll attenuate normally.... or they won't really take off well at all. So, either you'll have normal attenuation by the intended yeast, or zero attenuation, or variable attenuation due to no competition with contamination by wild organisms. It's one of the three things will happen.
I have experienced this effect myself, so i don't think it is a myth. I explain it to myself the following way, which does not necessarily mean it is the truth, I am just trying to make sense of it.

The longer the sugar gets, the more "active" does the yeast need to get to metabolize it. The longer chains have to be transported through the membrane or externally being chopped into shorter chains via excreted enzymes, but those enzymes are only excreted by diastaticus strains.
Other strains have to deal with what they have another way. My guess is, that each cell can only deal with a limited amount of longer sugars, before she has no capacity left to transport it into the cell or whatever other limiting factor there might be. This means that with a higher cell count, more of the longer sugars would be fermented. There obviously are multiple higher sugars, some might be completely inaccesseble for the yeast, explaining why huge numbers does not necessarily mean huge attenuation.
 

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Thanks. I often do an acid rest for hefeweizen so I was thinking to pull the extra wort out after or after a short protein rest. Either way before getting to anything above 131F. It would be slick to get the temps right so just the addition would bring the entire mash down to 144F from the 161F rest.

I have been hearing more and more about the importance of a prolonged mashout rest. Anything further to add about its importance? Seems like head retention is a major benefactor. Thanks.
I really just do it for the head retention boost, although I heard that it should also extract more flavour from the grain? But I am not sure about that....

Anyway, 15 to 20 minutes should be enough.
 

brewbama

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If you underpitch, I think you'll either get the yeast to multiply to the point where they'll attenuate normally.... or they won't really take off well at all. So, either you'll have normal attenuation by the intended yeast, or zero attenuation, or variable attenuation due to no competition with contamination by wild organisms. It's one of the three things will happen.
I agree. I used the same wort and pitched one pack in one (a bit under pitched) and two packs in another (a bit over pitched). The batch with one pack actually attenuated one point lower than the batch pitched with two. Grain wants to be wort. Wort wants to be beer. ...and yeast want to make it happen.
 

Robert65

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@mongoose33,

I think we're actually in fundamental agreement on the most important point: There's no on/off switch involved. It's all a continuum, which was not reflected in the old lists of conditions for, well, flipping switches found in texts and manuals up to the last couple of decades (thinking the likes of The Practical Brewer from the MBAA, and all the classic homebrew books.) I can't offer a simple bibliography at this point (I wish I did have a mental list of every paper and book I've read with a built in index,) but this is the general drift of all the work done in the last few decades it seems. The recognition of fuzziness that earlier science perhaps overconfidently underestimated. One thing to note is that it seems the time and temperatures for denaturing are often stated as a kind of half life: at X temperature, activity decrease Y% in Z minutes. That seems to fit with what you bring in, that denaturing almost begins right at activation, that decline happens even within the optimum environment. And it would be nice to have a table of just how each enzyme declines, but I also think the general idea here suggests that it's not really of great practical significance.

If we want to focus on the practical aspects, I think my main takeaway would be the idea that you can influence enzymes with a mash program, with very significant effects, but not ever strictly control enzymes: no light switches, and all enzymes active for at least some period of time under ANY reasonable mash conditions. This also of course implies that there are multiple possible ways to manipulate them to the same end. As to your concern about mashing in, I'd agree that not only with highly enzymatic malts but even standard European malts, no meaningful damage is done at mashing in. Especially when we remember that even British malts have DP upward of 70 Lintner and as little as 30 is sufficient in an all malt mash. And we simply may have a different perspective on time frames. When you suggest that enzymes can denature within a "normal" time, I don't see it the same, because I think 15-30 minutes at any given rest temperature should be sufficient to elicit the desired result. You can get your mash done with loads of time to spare. (I'm generally a 3-step, 90 minute guy, the "Hochkurz" I referenced earlier.)

And if I don't have links or citations to everything I've ever read, I'll say that my general advice is always to start with the textbooks. Briggs, Boulton, Brookes and Stevens, Brewing: Science and Practice and Kunze, Technology Malting and Brewing are current. (I trust professional literature over BYO or CB&B any day; I always wonder how far into an issue I'll get before I stop reading because some blatant misinformation is messing with my blood pressure. Though I can't take issue with what you've cited.)

I like this thread.
 
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JimRausch

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God I love this thread!
I started 7 years ago with a 5 gallon Denny-style cooler, and until a year and 1/2 ago it was the only system I used. Early on I decided that step mashes were the thing, but I would tend to fill my mashtun to the top. So, to do a step rise in temp., I decided that a decoction was the way to go. I would mashin at 145 and after 10 minutes take 3qt of a thick decoction, do a step to 155 for 10 min, then boil and add it back to the main mash which would raise the whole mash to 155. Total mashtime would take 75 minutes, and I convinced myself that if it was good for the germans, then it's good for me. Did it make a difference? Don't know, but it didn't hurt. I now have a larger capacity mashtun and most of the time do a single temp mash at about 149, but I still do my decoction for altbiers and lagers. I also do it on the rare occasion when my initial mash temp is lower than I want it.
 

brewbama

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God I love this thread!
I started 7 years ago with a 5 gallon Denny-style cooler, and until a year and 1/2 ago it was the only system I used. Early on I decided that step mashes were the thing, but I would tend to fill my mashtun to the top. So, to do a step rise in temp., I decided that a decoction was the way to go. I would mashin at 145 and after 10 minutes take 3qt of a thick decoction, do a step to 155 for 10 min, then boil and add it back to the main mash which would raise the whole mash to 155. Total mashtime would take 75 minutes, and I convinced myself that if it was good for the germans, then it's good for me. Did it make a difference? Don't know, but it didn't hurt. I now have a larger capacity mashtun and most of the time do a single temp mash at about 149, but I still do my decoction for altbiers and lagers. I also do it on the rare occasion when my initial mash temp is lower than I want it.
I have a denny style cooler as well but added a RIMS tube for the same step mash reason.
 
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I've heard this before, and I do NOT agree with it at all. If you underpitch, I think you'll either get the yeast to multiply to the point where they'll attenuate normally.... or they won't really take off well at all. So, either you'll have normal attenuation by the intended yeast, or zero attenuation, or variable attenuation due to no competition with contamination by wild organisms. It's one of the three things will happen.
I agree with this. It seems US brewers are heavily overpitching if u compare the rates with what UK brewers are pitching.
Also there is no specific way to calculate how much yeast you need. Different yeasts needs different pitching amounts. The only way to know this is from experience.
 

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