Author Topic: Iodine Test from WHERE?  (Read 1428 times)

Offline bspisak

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Iodine Test from WHERE?
« on: January 15, 2010, 09:14:17 PM »

So, I'm waiting for my pilsner mash at 147 to convert.... keep testing from the top of the mash and keep getting black.  I'm pushing 2 hours and still showing starch... light bulb... I check from a bit of runoff from the valve and viola!  I show good.  I test again from the top and show black.

So... what's going on?

Offline Kaiser

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Re: Iodine Test from WHERE?
« Reply #1 on: January 16, 2010, 07:16:27 AM »
Have you been stirring the mash?

In you case I would have also checked that the well mixed wort collected in the kettle is iodine negative.

Kai

Offline bspisak

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Re: Iodine Test from WHERE?
« Reply #2 on: January 16, 2010, 09:43:34 AM »

Yes, I stirred quite a bit. I hit gravity so I definitely converted and with the efficiency I was targetting.  I've not seen this happen before and still can't explain it.

Offline denny

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Re: Iodine Test from WHERE?
« Reply #3 on: January 16, 2010, 09:47:54 AM »
That kind of result is why I gave up on that test many years ago.
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Offline ndcube

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Re: Iodine Test from WHERE?
« Reply #4 on: January 18, 2010, 05:53:48 AM »
Is stirring during the mash necessary for complete conversion?

I've never done the test but I only stir in the beginning and get 80-85% efficiency on 1.050ish beers batch sparging..

Offline majorvices

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Re: Iodine Test from WHERE?
« Reply #5 on: January 18, 2010, 07:11:34 AM »
That kind of result is why I gave up on that test many years ago.

+1 - at 147 for two hours you are going to have conversion. Iodine test is a lot of false positive - or vise versa. Especially since the presence of husk material throws off the reading.
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Offline Kaiser

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Re: Iodine Test from WHERE?
« Reply #6 on: January 18, 2010, 08:20:23 AM »
Is stirring during the mash necessary for complete conversion?

I don't think that it is necessary. But bspiak indcated that the top seemed unconverted while something drawn from the bottonm seemed converted.

Kai

Offline denny

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Re: Iodine Test from WHERE?
« Reply #7 on: January 18, 2010, 10:03:07 AM »
Is stirring during the mash necessary for complete conversion?

I don't think that it is necessary. But bspiak indcated that the top seemed unconverted while something drawn from the bottonm seemed converted.

Kai

Which could be the case, or possibly he got husk or something else from the top that was giving him a false reading.
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Offline slimsparty

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Re: Iodine Test from WHERE?
« Reply #8 on: January 18, 2010, 01:41:48 PM »
At risk of Jinx-I also gave up on that.  I gave up on PH strips too.

I'm going to put my efforts into speeding up my brew and hitting numbers.

Offline Thirsty_Monk

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Re: Iodine Test from WHERE?
« Reply #9 on: January 18, 2010, 01:57:49 PM »
At risk of Jinx-I also gave up on that.  I gave up on PH strips too.

I'm going to put my efforts into speeding up my brew and hitting numbers.

Once we get comfortable with brewing process we do not need tto measure everything.
Let say I almost do not bother measure FG any more.
Beer should be fermented in 2 weeks.
If it is not, brew another beer and make it ferment in 2 weeks.

You can just say if mash is converted or not just looking at it.

Brew more = become a better brewer.
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Offline bspisak

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Re: Iodine Test from WHERE?
« Reply #10 on: January 18, 2010, 03:22:56 PM »

Since I wasn't very careful about what was in the sample I took from the top, I'm sure it was husk or some other non-convertable debris that was the culprit.

Thanks for the help!

Offline ndcube

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Re: Iodine Test from WHERE?
« Reply #11 on: January 19, 2010, 03:57:23 AM »
At risk of Jinx-I also gave up on that.  I gave up on PH strips too.

I'm going to put my efforts into speeding up my brew and hitting numbers.

Once we get comfortable with brewing process we do not need tto measure everything.
Let say I almost do not bother measure FG any more.
Beer should be fermented in 2 weeks.
If it is not, brew another beer and make it ferment in 2 weeks.

You can just say if mash is converted or not just looking at it.

Brew more = become a better brewer.

Yeah, but pH strips are easy and even if you don't make an adjustment you'll have notes for next time.  I guess if it's a mash that you've done a few times and get the same results then it's a waste of a pH strip.