Iodine Test

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IllusionOfTime

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So, I'm in the middle of my first partial mash, and I want to make sure that all of the sugars have converted... I've checked the Wiki, and I haven't see anything noted of the Iodine test...

I watched Yuri's video's a while back where he did the test, however I can't find it currently. I think that I remember that I just put Iodine on a white surface, and then a spoonfull of the mash liquid and it should be a color, however, I do not remember the proper color...

So, I've got about another 30 min or so on the mash, so I'll obviously be checking back fairly often... :)
 
I wouldn't worry about it. If you mash for 60 minutes at a decent temperature (150-156, depending on the maltiness you want), it will very likely be fully converted. I've never done an iodine test and probably won't ever do one.
 
It turns black with starch, if it's fully converted the color will stay yellow/orange.

Starch Test: Add Iodine-KI reagent to a solution or directly on a potato or other materials such as bread, crackers, or flour. A blue-black color results if starch is present. If starch amylose is not present, then the color will stay orange or yellow. Starch amylopectin does not give the color, nor does cellulose, nor do disaccharides such as sucrose in sugar.

BTW, I've been wondering - is there any reason one could not use a drop of Iodophor to perform this test?
 
Yes, iodophor works. I use the technique from Braukaiser's Wiki, dab some wort on a piece of sidewalk chalk, then a drop of iodophor. If it turns black, starch. If it stays yellow, no starch. Carve chalk with chisel to expose clean surface and you're ready for the next test.
 
Excellent, I did the mash at ~155 for 60 min so I think that I'm good. I did the test and it didn't turn black, so I think I'm in the clear. Good times. Thanks... :)
 
I'm kinda colorblind and I don't really see much of a difference in the iodine between "fresh" (5 mins in) and "ready" (60 + mins, obviously converted) mash. Is there another way besides tasting for sweetness? Some past tests will turn yellow in my eyes after a quick swirl on the white plate. I assume this means conversion? Any other colorblind imput would be well appreciated. For the record, I have trouble seeing greens against prime colors and purples against reds/blues.
 
The converted results are pale; the unconverted results are dark. It's a pretty stark contrast. This is a much clearer indication than you will normally get, but for comparison purposes:

Starch%20test.jpg


In this picture, the left tube is positive for starch. Right is negative for starch.
 
Not completely a color thing, but I've noticed that when opening the mash tun, if the top of the wort has sort of an iridium shine to it then it is converted. The best way I can explain it is the shine you get off of a bubble solution (soap and water).
 
Yep, iodophore works (which is good, since iodine is tougher to find due to meth lab scare). I've never tried the sidewalk chalk. My kids go through it too fast. However, I use either a saucer or the lid of a bucket. I put a drop or so of iodophore on there and a drop of mash liquor and tease the two together.


TL
 
I wouldn't worry about it. If you mash for 60 minutes at a decent temperature (150-156, depending on the maltiness you want), it will very likely be fully converted. I've never done an iodine test and probably won't ever do one.

I used to think this way. I tried one time after I had a low gravity. It proved to be beneficial because several times after 60 minutes I have found starch in the mash.
 
I used to think this way. I tried one time after I had a low gravity. It proved to be beneficial because several times after 60 minutes I have found starch in the mash.

I agree. Do the test!

I had a mash, once time, that went for an hour. I figured I was good to go, but went ahead and did the test. It turned VERY purple to my great surprise. It turned out my thermometer was messed up and I had been mashing somewhere around 140ish for an hour - not a whole lot of converting goin' on there. A couple gallons of boiling water and a bit more time later, I was all fine. However, had I just started lautering, I would have been VERY unhappy with the results.

An iodine/iodophore test is a quick, simple, and reliable check on how things are going. There is no good reason to skip it. If you find yourself just out of the stuff, at least give your wort a taste to see if is starchy.


TL
 
When using the iodophor, do you use it straight from the bottle or diluted?

I dilute it about 1:5 with water or ethanol.

Here is a cool series of iodine tests I took on a piece of drywall for one of my batches. I generally don’t go that far and take repeated samples. Just at the end of the mash to be safe:

batch_61_iodine_test.jpg


Kai
 
What happens when you try to do an iodine test on a dark beer, like a porter/stout, which is already black?
 
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