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Old 09-08-2011, 06:56 PM   #1
kal
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Many people (especially those prone to stuck sparges) 'mash-out' by raising their mash to 168-170F before sparging. It helps make the grain bed and wort more fluid.

Makes sense.

One of the other benefits to a mash-out that I often read about is that "at 168-170F all enzyme action stops which preserves your fermentable sugar profile".

Huh?

I don't get the "preserves your fermentable sugar profile". Can someone explain? Assuming that you mash until conversion is (close to) 100% complete, there's really nothing else to convert so the 'sugar profile' should be at at an end state no longer able to change. No?

So what exactly is being preserved?

Thanks!

Kal

 
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Old 09-08-2011, 07:20 PM   #2
ellisonsj
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Not all of the sugars created during the mash are fermentable. When you're mashing in mid to high 150s the enzymes that break down the larger, less fermentable sugars are not as active and to some extent denatured. In this case your wort is going to give you a sweeter beer with more body from these larger sugars. By mashing out at 168 or so you are causing all of the enzymes doing the conversion to denature, stopping them from doing anything to the sugars. If you were to skip the mash out the enzymes could keep working, and if the temp drops back down below 150 they're going to break down a lot of those large sugars into much more fermentable sugars, resulting in a dryer finished product.

Palmer explains how all the differnt rests and enzymes work pretty thoroughly in How to Brew, but this is the basic idea.

 
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Old 09-08-2011, 07:29 PM   #3
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Nothing in the mash follows a defined set of parameters. The enzymes within are varied among states of dormancy, minimized metabolic states, maximized metabolic states, and denaturization. The variables effecting these states are temparature and pH. As the variables fluctuate in intensity so does the activity of the enzymes most comfortable with those parameters.

Thus, while you may have the temps at the lower end of the scale that does not mean that everything else is shut down. And vice versa.

By performing a mash out you are denaturing all the enzymes thus locking down the fermentability of the wort while performing the sparge and while bringing the kettle up to a boil. Without this mash out there is still enzymatic activity occuring aomg the latter stages.

If your target is a beer full of body and short of attenuation then locking off conversion is a good thing.

 
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Old 09-08-2011, 07:41 PM   #4
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Got it! Thanks guys. This makes a lot more sense now.

I wonder why Palmer in his text in "How to Brew" however specifically states that mash-out "preserves your FERMENTABLE sugar profile". It should really say "preserves your sugar profile" (both fermentable and non-fermentable), no?

Kal

 
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Old 09-08-2011, 07:42 PM   #5
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Yea. That would make more sense. It keeps the unfermentables from being further converted.
__________________
Fermenter 1: Beer
Fermenter 2: Beer
Fermenter 3: Not Beer
Fermenter 4: Beer

 
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Old 09-08-2011, 08:11 PM   #6
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The beta-amylase, which produces most of the fermentable maltose, is quickly denatured at those higher temperatures (167-170F).

At those elevated temperatures, alpha-amylase is still active, though denaturing also, and this helps increase efficiency as it works at an increased rate to convert any remaining accessible starch into dextrins (unfermentable, long-chain sugars).

 
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Old 09-09-2011, 03:53 AM   #7
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Thinking about this some bit, if unfermentables are converted to fermentables then I suppose it does indeed change the "fermentable" sugars profile too so the wording is correct (since the sugars are either one or the other and changing one affects the other).

Kal

 
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Old 09-09-2011, 07:48 PM   #8
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Quote:
Originally Posted by kal View Post
Thinking about this some bit, if unfermentables are converted to fermentables then I suppose it does indeed change the "fermentable" sugars profile too so the wording is correct (since the sugars are either one or the other and changing one affects the other).

Kal
Yep. Tomatoe, tomahtoe.

 
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Old 09-15-2011, 06:05 PM   #9
audger
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Quote:
Originally Posted by ellisonsj View Post
If you were to skip the mash out the enzymes could keep working, and if the temp drops back down below 150 they're going to break down a lot of those large sugars into much more fermentable sugars, resulting in a dryer finished product.
the danger isnt if the temperature drops back down that the enzymes will re-activate. once thy are denatured thats it. the reason to mash-out to 170-ish is because you want to make sure they are ALL denatured and stop working. after you mashout the temperature can fall again and nothing should happen to the flavor profile as its now locked-in, essentially.

 
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