Iodine for Starch/Sugar test - Home Brew Forums
Register Now For Free!

Home Brew Forums > Home Brewing Beer > All Grain & Partial Mash Brewing > Iodine for Starch/Sugar test

Reply
 
Thread Tools
Old 04-18-2012, 11:22 PM   #1
Super64
Recipes 
 
Dec 2010
Pepperell, MA
Posts: 102
Liked 8 Times on 4 Posts



I just did my first all grain batch. One of the steps was was to test for the completeness of starch to sugar conversions was the old high school iodine test. I bought a "tincture of iodine" from Rite Aid. Unfortunately, it was "decolorized", which appeared yellow and stayed yellow on both a slice of bread and a pile of flour, meaning I had no way to measure the conversion

Does anyone do this test and where do you get the correct form of iodine to check for remaining starch?

Thanks.

 
Reply With Quote
Old 04-18-2012, 11:41 PM   #2
Reno_eNVy
 
Reno_eNVy's Avatar
Recipes 
 
Oct 2008
Reno, Nevada
Posts: 6,277
Liked 229 Times on 195 Posts


Do you use iodophor sanitizer? Because that works.

If not, why not just great straight up iodine instead of a tincture?
__________________
Primary: air and sadness =(

Kegged: air and sadness =(

Bottled: English Barleywine (brewed 9/26/09 -- bottled 5/5/10)


LET'S GO LA!
LA CAMPEONES!
PLAY FOR GLORY, THE GLORY LA!

 
Reply With Quote
Old 04-19-2012, 11:33 AM   #3
Super64
Recipes 
 
Dec 2010
Pepperell, MA
Posts: 102
Liked 8 Times on 4 Posts


It appears that "straight" iodine is not easy to come by at the retail drug stores.

I did see that others, like you, have suggested iodophor as the best option.

My local brew supply shop has it, so that's what I'll will use.

Thanks.

 
Reply With Quote
Old 04-19-2012, 05:18 PM   #4
jimbot
Recipes 
 
Dec 2011
Raleigh, NC
Posts: 37
Liked 5 Times on 4 Posts


I spent a while trying to find proper iodine, and finally read something stating that in my state they can't sell it anymore. Apparently it can be using in making meth. So the tincture is the way to go, at least in some states.

I found some tincture (providone-iodine) at Walmart, and saw some more at a Rite-Aid. And THEN I finally saw some at my LHBS.

I also want to mention that you will want to add a few drops of the solution to your mash sample, and then stir it in. The first couple times I had done this test I had omitted the stirring and was generally confused why it wasn't changing color. But after stirring, the reaction should happen. I always do this test now before sparging.

--Jimbot

 
Reply With Quote
Old 04-19-2012, 05:46 PM   #5
Denny
HBT_LIFETIMESUPPORTER.png
Recipes 
 
Jun 2005
Eugene, OR
Posts: 4,864
Liked 678 Times on 487 Posts


The iodine test is a waste of time IMO. You can easily get false results and even if you get good results it tells you nothing about the state of the sugars you have. If you really want to know if you have complete conversion, use Kai's spreadsheet and look at the gravity.
__________________
Life begins at 60....1.060, that is!

www.dennybrew.com

http://www.experimentalbrew.com - "Homebrew All Stars" now shipping!

 
Reply With Quote
Old 04-19-2012, 05:50 PM   #6
rhamilton
Recipes 
 
Sep 2011
Austin, Texas
Posts: 1,249
Liked 66 Times on 54 Posts


Quote:
Originally Posted by Denny View Post
The iodine test is a waste of time IMO. You can easily get false results and even if you get good results it tells you nothing about the state of the sugars you have. If you really want to know if you have complete conversion, use Kai's spreadsheet and look at the gravity.
Yea if you are getting grain husks in your sample, yea -- it can be false. But iodine test is a good tool, especially for noob AG brewers for indicating when conversion is complete.
__________________
On Deck: Cornucopia Oktoberfest
Primary: Centennial Blonde v2, Ed Wort's Kolsch
Secondary: none
Kegged: County Jail Pale Ale, AHS Anniv IPA, AHS Brooklyn Brown, Raspberry Wheat, Blood Orange Hefe, Ranger IPA clone (x2), Newcastle clone, AHS Irish Red, Centennial Blonde
Bottled: Session Series Belgian Saison, Apocalypso, Pecan Porter, DFH 90 Minute Clone, Apfelwein (x2), Wytchmaker Rye IPA Clone, Vienna/Simcoe SMaSH, Munich/Cascade SMaSH

 
Reply With Quote
Old 04-19-2012, 06:29 PM   #7
Denny
HBT_LIFETIMESUPPORTER.png
Recipes 
 
Jun 2005
Eugene, OR
Posts: 4,864
Liked 678 Times on 487 Posts


I'm sorry, but I just can't agree it's a good tool when I so often hear "I mashed for 4 hours and the test says I still haven't converted". Just forget about it...if you mash for 60 min. at the proper temps and pH, you WILL have conversion. And there's a wide range of temps and pH that will work. You have to be wildly off on both to not convert. And like I said, if you want to check, a far better tool is http://braukaiser.com/wiki/index.php...ion_Efficiency
__________________
Life begins at 60....1.060, that is!

www.dennybrew.com

http://www.experimentalbrew.com - "Homebrew All Stars" now shipping!

 
Reply With Quote
Old 04-19-2012, 07:40 PM   #8
Reno_eNVy
 
Reno_eNVy's Avatar
Recipes 
 
Oct 2008
Reno, Nevada
Posts: 6,277
Liked 229 Times on 195 Posts


I've never had a false positive for starch when using iodophor for testing.
__________________
Primary: air and sadness =(

Kegged: air and sadness =(

Bottled: English Barleywine (brewed 9/26/09 -- bottled 5/5/10)


LET'S GO LA!
LA CAMPEONES!
PLAY FOR GLORY, THE GLORY LA!

 
Reply With Quote
Old 04-19-2012, 07:42 PM   #9
Varmintman
Recipes 
 
Mar 2012
idaho falls, idaho
Posts: 2,102
Liked 663 Times on 416 Posts


I use it simply because if I get good conversion at 45 minutes I go ahead and start sparging. A couple of drops and some time saved.

 
Reply With Quote
Old 04-19-2012, 08:03 PM   #10
rhamilton
Recipes 
 
Sep 2011
Austin, Texas
Posts: 1,249
Liked 66 Times on 54 Posts


Quote:
Originally Posted by Denny View Post
I'm sorry, but I just can't agree it's a good tool when I so often hear "I mashed for 4 hours and the test says I still haven't converted". Just forget about it...if you mash for 60 min. at the proper temps and pH, you WILL have conversion. And there's a wide range of temps and pH that will work. You have to be wildly off on both to not convert. And like I said, if you want to check, a far better tool is http://braukaiser.com/wiki/index.php...ion_Efficiency
I'll use that formula next time I brew and see how it goes, especially since I just got an auto-temp correcting refractometer. But if an iodine test fails after that long -- I imagine the brewer either doesn't know how to take a clean sample or overheated and denatured the conversion enzymes and botched the mash.

But I like the iodine test -- especially as a BIAB'er since most people suggest 90 minute mashes when doing BIAB. When an iodine test is clear @ 45 minutes, I can mashout immediately, hit my calculated OG, and save 45 minutes on the brew day and be confident I didn't leave any starched unconverted.
__________________
On Deck: Cornucopia Oktoberfest
Primary: Centennial Blonde v2, Ed Wort's Kolsch
Secondary: none
Kegged: County Jail Pale Ale, AHS Anniv IPA, AHS Brooklyn Brown, Raspberry Wheat, Blood Orange Hefe, Ranger IPA clone (x2), Newcastle clone, AHS Irish Red, Centennial Blonde
Bottled: Session Series Belgian Saison, Apocalypso, Pecan Porter, DFH 90 Minute Clone, Apfelwein (x2), Wytchmaker Rye IPA Clone, Vienna/Simcoe SMaSH, Munich/Cascade SMaSH

 
Reply With Quote
Reply
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Iodine starch conversion on wheat beers McKinley All Grain & Partial Mash Brewing 7 06-30-2014 03:40 PM
Is the iodine test the only way to test starch conversion? worldzfree All Grain & Partial Mash Brewing 6 02-12-2011 09:18 PM
iodine test, where to buy suitable iodine? nathan All Grain & Partial Mash Brewing 7 04-26-2010 12:58 PM
Starch To Sugar Iodine Testing Question.. LIVETOBREW All Grain & Partial Mash Brewing 6 03-01-2009 01:52 PM
iodine test for starch converstion in AG batches Walker All Grain & Partial Mash Brewing 11 03-07-2006 10:39 PM


Forum Jump