Has anyone used the maltase rest ?

[brewtim]

Doing a bit of research into Wheat beer mash schedules and came across this snippet (from The Theory of Mashing):

Maltase

Maltase converts maltose into glucose. It is therefore an important enzyme for the yeast. But it is also present in malt. But since its temperature optimum is between 95ºF (35ºC) and 104ºF (40ºC) [Narziss, 2005] and it is being deactivated above 115ºF (45ºC), this enzyme does not play any significant role in most mashing schedules since higher temperature rests are necessary to genate glucose for this enzyme.

It is however used in a masching schedule developed by Markus Hermann from the Weihenstephan brewing school in Germany. This mash converts half the mash to get a large amount of glucose. After that conversion is complete, it is mixed with the remaining mash to achieve a rest temperature of 95ºF (35ºF) where the maltase converts the now existing maltose to glucose. After that the whole mash is again run through a regular mashing schedule to convert the remaining starch to matose and dextrins. The result is a wort with a very high glucose content (about 40% of the fermentable sugars). Yeast fermenting such a wort will generate more esters, a property that can be used to produce German wheat beers with a high ester content.

It would appear to be another way of increasing esters as well as a ferulic rest and stressing the yeast, anyone tried it?

 

[evanvine]

Bloody hell Tim!
I thought home brewing was meant to be simple, not rocket science.
Don't esters cause headaches?

 

[Dr Mike]

Maybe I'm missing something but I don't see how a Maltase rest could ever work in a mashing schedule. If you put it in at the start there would be no maltose for it to work on. Once the mash is warm enough to generate maltose, the Maltase enzyme has been wiped out.

If you give your mash long enough at the upper end (66 to 70C) them maybe the alpha amylase will hack all the maltose up into glucose ?

What is the link between Glucose level and ester production ?

 

[NickW]

Where's Pittsy when you need him?

 

[pittsy]

:hmm: Interesting sounds a lot like preparing raw wheat for mashing (sort of ) . Ferulic rest is pointless imo as it was used to drop ph of mash but would take hours to work and is not needed , i have not noticed a difference when doing a rest there . mashing in the 40's plays with the clove and in the 50's effects esters , protein . Even i wouldn't go that far in a mash mainly because i already get to adjust as is .

 

[jkp]

I don't see how a Maltase rest could ever work in a mashing schedule. If you put it in at the start there would be no maltose for it to work on. Once the mash is warm enough to generate maltose, the Maltase enzyme has been wiped out.

I understood the comment as being that the grain bill is split in half, one half is mashed to produce maltose, then it is mixed with the other half (which still has the Maltase enzyme) to get a 35-40*C mash and convert that Maltose to Glucose.

 

[rpt]

Don't esters cause headaches?

Esters are flavour compounds. Perhaps you are thinking of fusel alcohols?

 

[NickW]

Don't esters cause headaches?

Esters are flavour compounds. Perhaps you are thinking of fusel alcohols?

I suppose there is a direct correlation between esters and fusels. Higher fermentation temps will cause fusel alcohol as well as more esters. Like rpt said, I don't think it's the esters that cause headaches.

 

[calumscott]

I don't see how a Maltase rest could ever work in a mashing schedule. If you put it in at the start there would be no maltose for it to work on. Once the mash is warm enough to generate maltose, the Maltase enzyme has been wiped out.

I understood the comment as being that the grain bill is split in half, one half is mashed to produce maltose, then it is mixed with the other half (which still has the Maltase enzyme) to get a 35-40*C mash and convert that Maltose to Glucose.

Indeed, but I still fail to see the point of creating glucose in the mash when the yeast is perfectly capable of (or may have been specifically bred to) metabolise maltose. If we had the ability to do this with sucrose then I could see the point as the enzyme used to cleave that into metabolisable monosaccharides is excreted into the wort/must and there is the suggestion that this could be a factor in the flavour profile when sucrose is fermented. There is no such issue with maltose, maltose is taken into the cell prior to cleavage, maltase is never excreted by the cell.

"Yeast fermenting such a wort will generate more esters, a property that can be used to produce German wheat beers with a high ester content." That's quite a bold statement. Frankly I don't believe it. The whole point of us using dextrose (glucose) in kit beer brewing is the exact reverse! It's extremely clean.

 

[brewtim]

Bloody hell Tim!
I thought home brewing was meant to be simple, not rocket science.

I thought that when I first started brewing, but the more I do and the more I read the more bio-engineeringly-chemically complex it seems to become, drinking the final product is easy :rofl:

Don't esters cause headaches?

No, esters are created by yeast during all fermentations, (you may be thinking of different (fusel) ethanols that are produced by yeast at higher fermentation temps that can lead to headaches), different styles of beer benefit from different types and levels of ester production and the resultant flavours that are produced. The brewer can use various mash and fermentation techniques and yeast selection to manipulate the production of different types and levels of esters for the beer style.

Here we are looking at Wheat beers which are known for their flavours caused by the deliberate production of esters, it is a feature of this style of beer.

What is the link between Glucose level and ester production ?

Glucose apparently stresses the yeast during fermentation and therefore produces esters (don't ask about the bio-chemistry, I don't have a clue)!

I don't see how a Maltase rest could ever work in a mashing schedule. If you put it in at the start there would be no maltose for it to work on. Once the mash is warm enough to generate maltose, the Maltase enzyme has been wiped out.

I understood the comment as being that the grain bill is split in half, one half is mashed to produce maltose, then it is mixed with the other half (which still has the Maltase enzyme) to get a 35-40*C mash and convert that Maltose to Glucose.

Yes that's how I understand it also (after 5 times of reading it)! You would do a rest between 60-65 C with half the grain, let the whole lot cool to around 35 C and then stir in the other half of the grain, there would be a slight temperature drop at this point so just heat to 35-40 C and rest, then continue with a normal mash after that. Glucose would then be soluble in the boil and into the fermentor which would then stress the yeast to produce esters.

 

[brewtim]

Even i wouldn't go that far in a mash mainly because i already get to adjust as is .

C'mon pittsy, surely the god of wheat could give it a blast!

:grin:

 

[brewtim]

Here's a bit more of interesting on the subject, some have tried it and got some more banana/clove, some didn't make much difference:

AHA Forum

Looks like it was proposed for commercially brewed wheat beer in tall conical fermentors.

Geek factor only maybe? :geek:

But then that thread does start to spin off into ester production in Belgians...... :whistle: :whistle:

 

[jkp]

Might be a silly question, but......
Why couldn't you just add glucose yourself rather than go through this more complicated mashing process?

 

[calumscott]

Might be a silly question, but......
Why couldn't you just add glucose yourself rather than go through this more complicated mashing process?

Silly questions are the ones you wished you'd asked but didn't.

Because just adding the dextrose would reduce the total amount of malt used and thereby reduce the amount of unfermentable longer chain sugars in the wort thereby reducing flavour, body and mouthfeel. :thumb:

 

[jkp]

Because just adding the dextrose would reduce the total amount of malt used and thereby reduce the amount of unfermentable longer chain sugars in the wort thereby reducing flavour, body and mouthfeel. :thumb:

makes sense....

 

[Dr Mike]

Might be a silly question, but......
Why couldn't you just add glucose yourself rather than go through this more complicated mashing process?

I think the brewer who 'invented' this was German so wouldn't want to add Glucose because of the Reinheitsgebot.