Benedict's Solution for Mash Conversion?

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rocketman768

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Anybody ever use Benedict's solution for testing mash conversion? It changes color with respect to the concentration of monosaccharides in solution, and I was thinking it might be a better test than iodine. Has anyone ever tried this, or do you have much experience with the solution that might indicate it would be a good/bad idea? It's not very expensive, and I was thinking about buying some on my last trip to the chemistry supply website.
 

menschmaschine

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If it only measures monosaccharides, I don't think it would be a useful test. Glucose only makes up 8-10% by weight of wort sugars. Now if there were a test to measure proportions of mono- AND disaccharides vs. dextrins, that would be useful to do post boil to predict attenuation.
 
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rocketman768

rocketman768

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If it only measures monosaccharides, I don't think it would be a useful test. Glucose only makes up 8-10% by weight of wort sugars. Now if there were a test to measure proportions of mono- AND disaccharides vs. dextrins, that would be useful to do post boil to predict attenuation.
Actually, Benedict's solution reacts with any reducing sugar. This would include maltose. Where is the breakdown of wort sugars by weight?
 
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rocketman768

rocketman768

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I found a website showing typical wort profiles here. If that's right, then about 90% of the fermentable sugars will react to the Benedict solution (all except maltotriose and sucrose). So, I assume Benedict's solution, at some concentration, might be a very good test.
 

menschmaschine

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Well, this brings up an interesting possibility. If there is an at-home way, whether with Benedict's solution or something else (or a combination of), to measure/calculate a proportion of unfermentable to fermentable sugars. That could be useful information for understanding how your brewhouse works in regards to mash and yeast performance.
 
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rocketman768

rocketman768

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How exactly would this solution be of benefit? Wouldn't knowing that there is still starch present (iodine) work better? Just asking.
Two reasons...

First, iodine does not react with amylopectin (a branched starch). So, it does not entirely tell the whole truth of starch conversion.

Second, Benedict's solution will actually tell you the DEGREE of conversion since it has a whole range of colors. Iodine is basically binary...it's black or it's not.
 
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Two reasons...

First, iodine does not react with amylopectin (a branched starch). So, it does not entirely tell the whole truth of starch conversion.

Second, Benedict's solution will actually tell you the DEGREE of conversion since it has a whole range of colors. Iodine is basically binary...it's black or it's not.
OK usefull to know.
 

shot0rum247

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I'll agree with that, any amount of movement from the aldehyde group to the hydroxyl group via the Benedict's reagent will cause a color change to a certain degree. Still....why not use our tongues :)?
 

ajwillys

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I'll agree with that, any amount of movement from the aldehyde group to the hydroxyl group via the Benedict's reagent will cause a color change to a certain degree. Still....why not use our tongues :)?
Cuz this is the Brew Science forum not the RDWHAHB forum.... which is actually where I belong. How did I get here? :D
 

Kaiser

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If Benedict's solution reacts with the reducing end of sugars it should also react with maltotriose, maltotretralose and so forth.

With respect to the binary nature of the iodine test, it also has various shades of color. Ranging from black-purple for amylose over a more reddish color for amylopectin and starches/dextines containing shorter sections of glucose chains arranges as helices to red for erythrodextrines which are large dextrines.

The iodine test is more useful for testing wort as it is sensitive to the length of the glucose chains. Long dextrines or even starches need to be eliminated b/c of the haze that they can create in the beer. Benedict's solution only signals the presence of reducing ends and their presence is not sufficient to indicate that no starches or large dextrins are left in the wort.

IIRC, Fix does offer a way to estimate the real degree of fermentability.
Do you remember how he does that?


Kai
 

GilaMinumBeer

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Do you remember how he does that?Kai
I will look it up tonight.

Edit: Twas yet another senior moment on my part. Somehow, I commited the Fix and Fix 1997 table on Sugar Proifiles as an indication of fermentability varied by temp., which is true except that the example was based solely on German Diat Pils malt. :drunk:
 
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