iodine test for starch converstion in AG batches

**Walker** · 03-07-2006, 08:02 PM

This is a verbatim PM I sent to BeeGee. He has a theory, but isn't sure if it's the Right Answer, so I'm throwing this to the wolves....

I've been putting more and more thought into AG brewing, and one thing I don't understand is the iodine test.

I know the basics.... if iodine touches starch it turns black, so you use iodine to see if you have converted the starch to sugar. (right?)

If so, how the hell do you ever get a NON-black test result with efficiency under 100%? If you haven't converted all the starch to sugar, won't the iodine always turn black??

Remember.... I know jack sh!t about AG brewing, but this is something I've been wondering about.

-walker

**Walker** · 03-07-2006, 08:05 PM

after another message from Billy, I think I might be confused about the term "efficiency".

Is that describing the conversion of starch into sugar, or is it describing the extraction of the sugar form the grainbed? (ie; ALL starch converts to sugar, and effeciency is a measure of how much of that sugar you extracted into your kettle.)

AG retard,
-walker

Kaiser · 03-07-2006, 08:14 PM

Quote:

Originally Posted by Walker

(ie; ALL starch converts to sugar, and effeciency is a measure of how much of that sugar you extracted into your kettle.)

You got it.

I have actually come across multiple definition of efficiency:

(extracted sugar) / (maximum extractable sugar) and
(extracted sugar) / (amount of grain used)

The latter seems to be common in German brewing literature and is called Sudhausausbeute (brew house efficiency). And yes wre have pretty long words in German.

Kai

**Walker** · 03-07-2006, 08:16 PM

ok. thanks for clearing that up.

The yahoo's can take this thread and run it into the weeds now.

-walker

Lou · 03-07-2006, 08:20 PM

Quote:

Originally Posted by Walker

The yahoo's can take this thread and run it into the weeds now.

yes! my time to shine!!!

i think enzymes are a government conspiracy!!! they're not real!!!!!

**Walker** · 03-07-2006, 08:24 PM

Quote:

Originally Posted by King Kai

yes wre have pretty long words in German.

Yes, you do, but the beauty is that you can almost always create the word you need (if you don't know the 'proper' word) by stringing together a bunch of small words that you DO know to get your point across.

That's what I LOVE the german language.

For those of you who think German is a guttoral, spit-filled language.... you obviously have never heard much DUTCH spoken.

Kaiser · 03-07-2006, 08:34 PM

Quote:

Originally Posted by Walker

Yes, you do, but the beauty is that you can almost always create the word you need (if you don't know the 'proper' word) by stringing together a bunch of small words that you DO know to get your point across.

We definitely have many concatenated words for which the English language has just a single word. But the concept of concatenated words is not foreign to English either, but there you keep a space between the words, which doesn't make the word look like one long word.

Kai

**Baron von BeeGee** · 03-07-2006, 09:00 PM

Iknowwhatyoumean.

**Baron von BeeGee** · 03-07-2006, 09:05 PM

Oh yeah...just for my edification. So we're saying that all starch gets converted to sugar if the iodine test is negative, but the efficiency is measuring how well you lauter the mash? Is poor efficiency then attributable to factors such as bits of converted starch getting stuck inside uncrushed/poorly crushed grains, just not getting sparged into solution, or get missed due to water channelizing and missing them?

Kaiser · 03-07-2006, 09:28 PM

Quote:

Originally Posted by BeeGee

Is poor efficiency then attributable to factors such as bits of converted starch getting stuck inside uncrushed/poorly crushed grains, just not getting sparged into solution, or get missed due to water channelizing and missing them?

yes, and 100% efficiency would not be goo since you have to do so much sparging, that you get tannins from the husks.

One of the parameters that are measured for malts are fine grain extract and coarse grain extract. For fine grain extract the malt is ground to flour, mashed to full conversion and then all the solid are removed. The extract is measured and expressed as % of the initial grain weight.The same is done for coarse grain extract, but here the malt is just crushed. This all is done in a laboratory setting.

here is malt info from a German maltster (Durst Malz): http://www.durstmalz.de/pilsnermalt.html

There you see Fine Grind extarxt and Fine Grind / Coarse Grind difference.

Kai