Does anyone know if iostar has enough free iodine in it to be used as a test for starch left over in a mash? And, if I find there is still starch in the mash after an hour, check the pH and temp and then let it just keep on going til the starch is gone?
Thanks.
I’m not sure about Iostar, but if you hit your mash temp and left it for an hour without losing much heat, I would not worry about taking an iodine test. Go ahead and lauter.
Dave
i have never done an iodine test. from other threads i am not sure it is all that worthwhil
I recommend you just forget the starch test entirely. It’s unnecessary unless you REALLY screw up and it’s easy enough to do the test wrong and get a false reading.
I tried using idophor for a starch test, couldn’t tell if it was changing or not. But I do know that when I dump strongish idophor down the sink I can see blue stains where starch is adhering to the SS of the sink so it should work in theory.
but +1 to not really needed unless you have concern about incomplete conversion in which case it might be worth while going to the drug store and getting some actuall iodine stuff.
I was wondering how others would respond to this. I have never done an iodine test either.
I read, somewhere, that if ythe liquid on top is clear after 60 minutes your mash is converted. For the most part. I have never done an iodine test but it seems to work for me.
YMMV and I may be completely whacked on this.
Paul
Old guy on the Moonshiners show last night stuck his finger in the mash and held it up in the wind. He said if it’s not sticky when it dries, it’s ready.
I’d think it should be sticky from the sugars. Seems like if it’s not sticky it hasn’t converted.
Who knows where else ol’ Jim Tom’s finger has been!!! 
I think iodine tests are useful and brewers should know how to do them correctly to troubleshoot mash conversion issues: Iodine Test - German brewing and more
Kai
Obviously if you’re going to do them you should know how to do them correctly. Unfortunately I’ve seen far too may people who don’t know how. And troubleshooting a problem is about the only use I can see for it. As a regular procedure it just seems pointless.
Kai,
What types of conversion issues have you seen? Are some more common than others?
Dave
As always, a perfect explanation from the Kaiser. Thanks!
To others, I am worried about doing this as a test for conversion efficiency, not just because I like adding extra steps to my brew day. I’ll pick up some Iodine and do it the right way.
So Jeff, do you perfrom an iodine test on every brew or just those that have a more complex malt bill?
Dave
Some we have done this fall were so clear, no need to. Sometimes the wife does it just because. If we have doubt, it is done as a go/no go test. Usually the result is to go ahead. The ones it has said not to go ahead on were high in dark munich malt. Now I have been adding 15 to 20% Pilsner to get some higher enzyme levels.
My wife was an elementary teacher. She would do the iodine on the potato test with the kids for science class, so she likes doing the iodine test, takes her back I think.
Maybe an iodine test is like parallel parking, unless you live in the city you rarely need it. Brewers should learn how to do the iodine test correctly but most of the time it is not needed.
The problem is that it doesn’t show you how well you mash converted the starches from the malt. For that you need to do a mash gravity test for conversion efficiency. I have a table here that shows what mash gravity to expect when all starches convert. I also worked with Larry from Brewer’s Friend to integrate that into BF’s log entries and have it report conversion efficiency. I also have a spreadsheet for this, but I’m finding it easier when the grain and water data comes directly from the recipe.
Like Jeff, I have found that dark beers tend to need more attention when it comes to conversion. They are sometimes slow to get into the mid to upper 90’s with respect to conversion efficiency.
Kai
Hey Kai - I have been using your table this fall for checking conversion eff.
Though I would give kudos for that.
The iodine test does not say what the sugar content is, it just says the starch has converted. It does not say into what. Conversion takes place quickly, to get the most out of the mash takes 60 to 75 minutes.
Good info guys, thanks!