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Old 03-25-2009, 05:47 AM   #1
giligson
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Default Want to determine the proportion of glucose created in a mash.

Here's my question. Perhaps someone can direct me. We know that mashing at different temperatures alters the carbohydrate profile of the wort. It creates a differently balanced proportion of mono, di, tri and higher polysaccharides. So a mash done at a lower temp will have more glucose and a mash done at a higher temp will favour more production of longer chain sugars. Does anyone have access to an easy referance or table that shows relative proportion of glucose (monosaccharides) produced at different mashing temperatures.

Why do I want to know this?
I was thinking of doing a high gravity brew, my fermentor has a higher capacity than my kettle. I wanted to create a proportionately low glucose (high temp) wort and balance it out with a dextrose and water addition at the end of boil to fill the fermentor to capacity. But I need a point of reference for roughly what proportion of the sugars will need to be supplemented by a dextrose addition.

If you understand my rather roundabout question, and have a document or link that may be of help, please let me know.

Cheers.

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Old 03-27-2009, 02:09 AM   #2
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The production of the various sugars in wort is dependent on more than temperature. It is also dependent on pH/minerals (water), water:grain ratio, etc. Therefore, it would be difficult to give a ratio of maltose to other sugars for any given temperature profile. I'm not saying such information does not exist for a typical wort, but it will vary from brewhouse to brewhouse.

Your best bet would be to experiment with it while keeping within the accepted limits of dextrose additions.

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Old 03-27-2009, 03:33 AM   #3
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^^^I agree, I dont think there is a method to tell how well the starches are broken down to maltose maltotriose or just plain glucose and how many are longer unfermentable chains. It really depends on the malt, pH, temp, and rest time. I know this isnt the answer you want but without testing the mash for each type of sugar I dont think there is any way to tell how much of each sugar you have. I do like your thinking though, make a full bodied beer then add the sugar that would be present in the beer had it been mashed at a lower temp. Best of both worlds.

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Old 03-27-2009, 03:49 AM   #4
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I've been wasting time all day looking up journal articles in the brewing literature online - its not my natural jargon so it makes for some thick reading - I find that some of the studies that folks have done come close but they don't give me exactly the answer I was looking for.

I think a more attainable goal might be to ask:
what percentage fermentables are produced for a given "typical" mash of 60 degrees C vs 70 degrees C. Do up an All Grain at the higher temp profile then "even out" the wort profile with an addition of Malt Extract (that way I don't have to worry about proportion of glucose, pentose, maltose, galactose....ad nauseum)
I think I'll have to have a look at that Brewing Science Principles and Practice text to see what I can make of it (found a PDF of it today).

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Old 03-27-2009, 04:54 PM   #5
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Quote:
Originally Posted by giligson View Post
I think I'll have to have a look at that Brewing Science Principles and Practice text to see what I can make of it (found a PDF of it today).
where at???
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Old 03-27-2009, 07:51 PM   #6
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Brewing, Science and Practice torrent
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This message in no way advocates the use of peer to peer file sharing sites.
I assume that if you are going to download any copyright material, you have the right and authorization to do so and have purchased a licence or have the express permission of the author.

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Old 05-24-2009, 08:23 AM   #7
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giligson - I don't know if this answers your question, but the generally accepted ratio that I've been taught is 1:4 of dextrins to fermentable sugars at 65C. Since it's a ratio, you shouldn't have to adjust for high gravity brews - they'll automatically have a proportionately higher level of residual sugars.

What you want to do is called 'liquoring back', which is the addition of water to wort. Easiest way to do this is figure out what you want your OG to be. Put as much wort as you can in your kettle, and do a regular boil. Then, check the gravity of your wort post-boil, multiply it by your copper volume (how much wort you have), and then divide by what you want your gravity for your fermenter to be. Boil up that amount of water and chill it like you would wort (this is to sterilise - optional, if you're not worried about bacteria in your water source) and then add it in before you pitch your yeast.

(gravity in kettle x copper volume) / desired OG = total volume
total volume - copper volume = liquor back volume

luck!

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Old 05-26-2009, 07:06 PM   #8
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figure 4.20 in Brewing Science and Practice shows you what you want. But this is only a snapshot for the conditions of the experiment. And most of the sugar you want to add is maltose anyway.

I suggest that you supplement with malt extract instead of glucose and mash as usual. This way you get the right distribution of sugars.

Kai

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