iodine test question

Production methods from starch to sugars.

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glassman
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iodine test question

Post by glassman »

have been wondering this: when i do my starch test with iodine the clear liquid on top will show no starch.....good. but if i stir up the fine boilings and test a cloudy sample the test shows incomplete convertion........but will it ever pass the test? or will there always be starch because there is ultrafine corn partcles in the sample? been wondering and am doing my 50lb pinto double lactic ferment. fyi....did my cook and steep and cool to 155f and charge with 10lb malt and 24gr enzyme combo. thanks, gman
Usge
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Re: iodine test question

Post by Usge »

As far as I know...."any" amount of solids or particulate will throw the iodine test off (ie..it will be purple) and even the tincture of iodine at very small percentages is very sensitive. The only thing you can measure is the clear liquid on top.
BW Redneck
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Re: iodine test question

Post by BW Redneck »

To quote Making Pure Corn Whiskey:
"You may observe tiny granular dots of blue in the sample when the iodine is added. This is not an indication of starch, but a result of cellulose from tiny particles of mash solid suspended in the sample. Iodine turns a dark blue, almost black, in the presence of cellulose in water. This is why you should take care to avoid getting the mash solids in the sample. Anyway, this cellulose indication can be ignored, and you can conclude that there are no residual starches in the mash."
In other words, don't stir off the bottom when trying to get a sample, because it will always throw it off with cellulose instead of starch.
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glassman
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Re: iodine test question

Post by glassman »

thanks for the help guys. now i just have to worry about getting all the starches out of the grain. gman
Usge
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Re: iodine test question

Post by Usge »

I find Dunders method of using a finer grind on cracked corn (run it through a barley crusher), enough water, and using a long interim steep in between first and last boil will pretty much render the corn out to the nub and nibblets.
glassman
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Re: iodine test question

Post by glassman »

i'm finding that it takes a long time to boil out the corn. i'm useing fine crack from southern states. useing my new/used 60 gallon steam kettle i got at auction. so far it seems very efficiant to use. boiled for 1 hour as we speak and still lots of corn left. did pintos sour ferment first. will boil another hour and check. thanks, gman
Usge
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Re: iodine test question

Post by Usge »

Let it steep/set for an hour or two...THEN boil it again. The steeping seems to loosen up the last bits of starch..and the last boil usually takes them right out.
glassman
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Re: iodine test question

Post by glassman »

simmered for 3 good hours and made a real nice poridge. will try this and see how it works. if not good enough then next run i'll do a double boil. wonder if i could just do away with the sour ferment? that adds 3 days to the mash. just add backset and cook. gman
JonB
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Re: iodine test question

Post by JonB »

So after successful boils and a nice long steep, what is the efficiency expected with cracked corn? I've been hitting the 60% barrier for some time, but I guess boiling it the 2nd time might raise this a bit. Info on the main site says that I should be closer to the 80% mark.

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Dnderhead
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Re: iodine test question

Post by Dnderhead »

its hard to tell with out knowing what you have, what you did. I hit 75-80% conversion.if that is what you mean. it does take a lot of cooking
for corn, it turns to mush, then add some malt/enzymes and cook some more (you can add some enzymes at start) corn will take about 45min to
one hour total cooking time.
JonB
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Re: iodine test question

Post by JonB »

Crap...another F**K up.

I tried another round of mashing and left the corn to cool slowly overnight. At 170F I mashed in my barley and let it cool slowly. I noticed that at 130 or so that the mash was not thick, but not real thin either. I crushed 2 beano tablets and stirred them in. At 100F I did an iodine test and it still seemed starchy to me. Iodine drop just stayed in the mix and didn't stain anything but where the drop fell. Thought this was due to stirring (I know...sample, then stir). Are there any photos of iodine test showing the good, the bad, and the ugly?

At 90F I added yeast.

This morning at work (while listening to a coworker drone on about something insignificant) I realized that I mashed in at 170F and not 150F. I probably killed most of the enzymes in my 2 row barley.

When I got home I saw that I do have C02 coming thru the airlock (its the 24 hr mark). Not as fast as I'm used to, but the bugs are still working. The wort is 80F now and I figured "what the heck" and I tossed in another 3 crushed beano tablets to see what happens.

So what could have been my best efficiency batch will probably be my worst. A few lessons learned at least. In the back of my mind I'm thinking of Ian Smiley's "no cook" mash recipie and hope that the yeast will be able to break down some of that starch as it works...
brewmaker1
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Re: iodine test question

Post by brewmaker1 »

Here ya go for pictures of the test: http://www.homebrewtalk.com/wiki/index.php/Iodine_test" onclick="window.open(this.href);return false;" rel="nofollow I hope I was reading your post wrong about where you did the test. It almost looks like you just put a drop of iodine in the mash.
trthskr4
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Re: iodine test question

Post by trthskr4 »

I wouldn't want any iodine in my mash, just doesn't sound good to me.

JonB, heat it back up to 150-155*F add in some more barley and let it cool and start all over. Mashing is too much work to let it half ass ferment.
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JonB
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Re: iodine test question

Post by JonB »

Thanks.

Fermentation was on day 3 when I checked the last post. Today is day 4 and its still bubbling. So I guess its not a complete loss. We'll see what happens.

Oh - I apologize for not being clear. Iodine is poisonous and so I would never put it in my mash....just my sample.
Fourway
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Re: iodine test question

Post by Fourway »

get some working enzyme in to the already fermenting slop. it still converts at room temp... just slower.
perfect time to switch gears and make it a SMOP mash.
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