Mash temps, times and fermability - Home Brew Forums
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Old 01-09-2012, 01:48 PM   #1
Clementine
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May 2011
Waynesboro, PA
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When I first started all grain about 6 months ago I asked the question on here how do I know the mash is done and all sorts of arguments started. I don't want to do that this time but rather talk about the effects of mash time and temps. People who do over night mashes claim that they don't see any large change in the mash just a bit better efficiency. When I have done longer mashes the beer has been very fermentable. A couple of months ago BYO did an article on When is the Mash done and although I like the article I thought there was more than needed to be investigated. Then for some reason I decided to watch Bobbys All Grain Series (Bobby great information in the third show about the effect of alpha and beta amylase) that he has on You tube and it got me thinking again about mash times and how important they are to recipes.

So here is the concept I would like to discuss. Mash times effect the fermability of a wort after the initial conversion of starch to sugars. I can probably best explain this with an example. Take a mash designed to give a sweeter beer say 156 deg F. Now after 20 or so minutes the mash is showing giving a iodine negative test showing the the starch as been converted. At this temp Beta Amylase is most active resulting in more complex sugars from the starch conversion. However the Alpha Amylase is still active and is going around making more simple sugars until stopped by the mash out where both alpha and beta amylase is denatured. So if you mash at 156 for 90 minutes you will end up with a more fermentable wort than if you mashed for 60 minutes.

I guess the opposing opinions could say that the higher temp is denaturing the alpha amylase over the period of the 60 mash and there an increase in time does not affect the amount of simple sugar in the mash or that the Alpha amylase has done as much as it can do after 60 minutes even though it is not operating at its ideal temp.

Anyway I put this out to the collective knowledge just so I can better understand my mash, also perhaps so I can better design an experiment to test my theory.

Clem



 
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Old 01-09-2012, 03:57 PM   #2
dcp27
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Jan 2010
Medford, MA
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you got your enzymes backwards. beta amylase is denatured pretty quickly at 156F so I wouldn't expect the extended mash that high to have much effect. Kai did some experiments on mash temp & time and its effect of extract and fermentability, that should answer most of your questions
Starch Conversion - German brewing and more



 
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Old 01-09-2012, 04:26 PM   #3
Clementine
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May 2011
Waynesboro, PA
Posts: 545
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dcp27 thanks for the link, so aside from having my amylases mixed up from what I have read in this link, it appears I'm after right in so far as if I have a wort sitting for longer than the standard 60min mash time the fermentability of the wort increases. However I was wrong in so far as the effect of increased time on fermentablility is more pronounced at lower temps where i thought this would be the opposite.

Clem

 
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Old 01-09-2012, 07:50 PM   #4
crackhead7
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Apr 2010
cleveland, ohio
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you are right hence the reason for the mash out. locks in the sugar profile

 
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