iodine test

[kegtoe]

I've done 5 or 6 all grain batches this year. i've been struggling with efficiency so i started doing iodine tests while mashing after the first two batches. Ive yet to see in black, purple when i add a drop of iodine to a few drops of wort on a white saucer. I have done this pretty early in the mach too and still have not seen a sign of starches not fully converted.

Could this be do to the type of iodine. Or wigh today's highly motified grains, does the conversion happen that fast?

Another question i have is around temperatures. Ive read that you want to stay away from 160 while mashing that it will stop starch conversion. So...if i got my mash temp up to 160 after 10 minutes of mashing i would expect a very low OG and some dark color when putting iodine into some wort?

 

[boo boo]

With todays grain starch is converted quick.

160 won't stop starch conversion. In fact it is within the Alpha range. Using 160 as a mash temp will cause you to get longer chain sugars which will mean a less fermentable wort and more residual sweetness, but you will still get conversion.

 

[kegtoe]

hmmm, interesting. So how quick can you expect to get fully converted. Why mash for 60 or 90 minutes then?

 

[Edcculus]

hmmm, interesting. So how quick can you expect to get fully converted. Why mash for 60 or 90 minutes then?

You can get full conversion in 20 min. I know they discussed this pretty thouroughly in the Brew Strong episode on either mashing or milling. If you did a congress mash (where you grind the entire grain into flour) it would fully convert in 20 min or less. Since you can't always fully crack open the endosperm, being in there for 60 min helps all of the starches get freed up. Try this - take a peice of grain from the mash, put it on the plate and add iodine. If you mush it around, it will turn black.

Also, just because all of the starch has been converted, doesn't mean its the right kind of sugar. If you mash for 15 min, you will likely get a wort high in dextrins. Not a bad thing, but it might not be the most fermentable wort. A 60 min mash assures you will get a properly fermentable wort. Knowing that conversion happens quickly, you are free to use time as another variable in the mash aside from temp.

 

[pretzelb]

I've struggled with the iodine test also. I did the same as you - add a drop to some wort in a white bowl. In my case it looks purple at first and I think "it's not converted" but then it seems to quickly dilute and I think "maybe it's done". I did this after 60 minutes and it does the same thing. What should be a simple test always trips me up.

 

[KoverinMcGroyne]

I have yet to try it but maybe the chalk method would work better. It seems to me that it would prevent the problem of the iodine diluting into the wort. At the very least it should give the time for a good long look at the results. I stumbled onto it in the wiki so here is the link.

https://www.homebrewtalk.com/wiki/index.php/Iodine_test

 

[pretzelb]

I have yet to try it but maybe the chalk method would work better. It seems to me that it would prevent the problem of the iodine diluting into the wort. At the very least it should give the time for a good long look at the results. I stumbled onto it in the wiki so here is the link.

https://www.homebrewtalk.com/wiki/index.php/Iodine_test

I've thought about chalk. I just hate having to buy it just because I'm too inept to test the other way.

 

[maida7]

I've done 5 or 6 all grain batches this year. i've been struggling with efficiency so i started doing iodine tests while mashing after the first two batches. Ive yet to see in black, purple when i add a drop of iodine to a few drops of wort on a white saucer. I have done this pretty early in the mach too and still have not seen a sign of starches not fully converted.

Could this be do to the type of iodine. Or wigh today's highly motified grains, does the conversion happen that fast?

Another question i have is around temperatures. Ive read that you want to stay away from 160 while mashing that it will stop starch conversion. So...if i got my mash temp up to 160 after 10 minutes of mashing i would expect a very low OG and some dark color when putting iodine into some wort?

I doubt conversion is what is causing your efficiency to be low. Perhaps your crush is too coarse and your not getting all the starch in contact with the liquid (mash efficiency). AND/OR your not doing a good job of rinsing the sugars off the grain (lauder efficiency)

Read this http://braukaiser.com/wiki/index.php/Efficiency