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Home Brew Forums > Home Brewing Beer > General Beer Discussion > Iodine Starch test
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Old 05-20-2010, 04:43 AM   #1
FenoMeno
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Default Iodine Starch test

I wanted to try the Iodine Starch conversion test. I bought Iodine Tincture 2% U.S.P. (first aid antiseptic) from the local pharmacy.

Never really got it to work. Even prior to sparging, the color stayed the same. Am I using the wrong stuff?


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Old 05-20-2010, 10:14 AM   #2
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If it stays the same color, you are fine. It turns black/purple in the presence of unconverted starch.

Next time try it on some mash liquid right after you dough in. Then you'll see it turn purple.


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Old 05-20-2010, 09:30 PM   #3
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I tried the test about 30 mins in to the mash, and the color already had not changed. I was wondering if the 2% U.S.P. was not enough iodine to make the test work.
Looks like some others are just using the cleaning solution iodophor...is that correct?
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Old 05-20-2010, 09:42 PM   #4
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Quote:
Originally Posted by FenoMeno View Post
I tried the test about 30 mins in to the mash, and the color already had not changed. I was wondering if the 2% U.S.P. was not enough iodine to make the test work.
Looks like some others are just using the cleaning solution iodophor...is that correct?
With the highly converted malt these days, conversion after 30 minutes is pretty common. I would test it at the beginning of the mash.
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Old 05-20-2010, 11:34 PM   #5
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Quote:
I wanted to try the Iodine Starch conversion test. I bought Iodine Tincture 2% U.S.P. (first aid antiseptic) from the local pharmacy.
Never really got it to work. Even prior to sparging, the color stayed the same.
Here is a sample of the most common test.
Put wort and Iodine into one cavity each as a control sample.
Put wort into one more cavity and add a drop of Iodine and watch the reaction and compare to the original color of the Iodine/wort.



A much better method is the chalk or Kaiser method I use.




Quote:
Looks like some others are just using the cleaning solution iodophor...is that correct?
Yes

Cheers,
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Old 05-21-2010, 04:15 AM   #6
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Quote:
Originally Posted by FenoMeno View Post
I bought Iodine Tincture 2% U.S.P. (first aid antiseptic) from the local pharmacy.
:
I probably have the exact same little brown bottle w/ tan label that you have (from walgreens) and yes, it will turn purple in the presence of starch.

Mine saved my butt on a largely wheat batch that wouldn't convert after an hour. Took 90 mins.
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Old 08-25-2012, 09:52 AM   #7
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Quote:
Originally Posted by FenoMeno View Post
I wanted to try the Iodine Starch conversion test. I bought Iodine Tincture 2% U.S.P. (first aid antiseptic) from the local pharmacy.

Never really got it to work. Even prior to sparging, the color stayed the same. Am I using the wrong stuff?
I just saw this now and wonderd if the OP ever go any results? I have also tried and failed but i used the "colorless/clear" iodine ticture and that does not work!! went for the "normal" one (brown'ish/yellow) and it works like a charm!!
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Old 08-25-2012, 12:44 PM   #8
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Thanks for the input. I did fine with the Walgreens bottle, but found it just as easy and much cheaper to use Iodophor which I already had for sanitation. both worked good-


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