Why doesn't my 10min-into-mash idodine-test turn blue?

[Smellyglove]

I took a small sample of the wort after about ten minutes into mashing. Added a few drops of iodine, and nothing happens.

Whut?

 

[RM-MN]

Converting the starches doesn't take an hour, it takes 2 to 3 minutes. The rest of the time is getting the water to the center of the grain particles and the sugars leached back out. If you only got the wort in the sample, you shouldn't have any change to the iodine. If you get some of the grains in and they show the blue that will mean that there is still starch in them to be converted.

 

[dryboroughbrewing]

Have a read of Kai Troester's work.

http://braukaiser.com/wiki/index.php?title=Iodine_Test

 

[Smellyglove]

Converting the starches doesn't take an hour, it takes 2 to 3 minutes. The rest of the time is getting the water to the center of the grain particles and the sugars leached back out. If you only got the wort in the sample, you shouldn't have any change to the iodine. If you get some of the grains in and they show the blue that will mean that there is still starch in them to be converted.

Thanks, that clears things up a bit. I thought you mashed for 60 minutes (example number) because of the conversion of the starches took so long.

Question 2: If I miss my strike temperature and go higher, will that be the types of sugars I will be extracting?

What about step-mashing. People do steps low, and high (not counting the mash-out). What's the point in doing that if the starches get converted in three minutes at the first temperature step?

 

[JimRausch]

The theory behind step mashing is that different enzymes have different temperature ranges where they work best, and act on the starch/dextrin molecules in different places. J.P.'s 'How to Brew' book has a simplified analogy that explains it well. If you have a copy, time to review. If you don't have a copy, go order the latest version, then go find the older online version and read up on it.

 

[Smellyglove]

The theory behind step mashing is that different enzymes have different temperature ranges where they work best, and act on the starch/dextrin molecules in different places. J.P.'s 'How to Brew' book has a simplified analogy that explains it well. If you have a copy, time to review. If you don't have a copy, go order the latest version, then go find the older online version and read up on it.

Yes, I know this. But if the starches are converted to sugars after 3 minutes then I can't see how there will be sugars left for the second rest to convert any starch.

 

[GilSwillBasementBrews]

My chemistry isn't all that great. But the lower temp steps I believe are for proteins rest, alpha and beta amylase rests. So lowest step first for protein rest, then the low mash temp rest for alpha amylase enzymes, then the higher mash temp rest for beta amylase enzymes. I believe. So you could hit all three steps and get the most ferment ability out of your mash. Or aim for a middle of the road temp and get general conversion of most of the enzymes.

With modified malts these days you generally can skip the different steps and get good conversion on a single infusion step at around 150-155F

 

[RM-MN]

Yes, I know this. But if the starches are converted to sugars after 3 minutes then I can't see how there will be sugars left for the second rest to convert any starch.

Most people do not have the fine crush that I do so while the conversion is quick, their grain particles are not wet through immediately and conversion won't occur in that part of the grain until it gets wet. You can convert the starches in the outer part of the grain particle at the low temp to get high fermentability while the inner part isn't converting because it is dry, then raise the temp as the particle gets wet farther in and get the alpha amylase enzyme to create dextrines in that part of the grain particle. The beta amylase will be denatured at higher temperature so the alpha amylase is the only enzyme acting on that part of the grain starches.

 

[Smellyglove]

Aha. Thanks.

Sent from my GT-I9300 using Home Brew mobile app

 

[pjj2ba]

Big starch chains are not very soluble in water, and clumps of starch chains even less so. You need make sure to stir the mash right before taking a sample or the strach chunks will have settled out, and it is the non-soluble starch that reacts with the iodine.

Mashing is kinda like making a reverse snowball (for a snowman). As the enzymes attack these big chains and clumps they get smaller and smaller. This is what takes time as you mash. The enyzmes don't have access to all of the starch at once. The enzymes have to pick away at the outsides. the smaller the initial particles the faster the conversion

Eventually if you are mashing well, the big chunks will be gone and all that is left is the husk, and the tiny shoot and scutellum (the scutellum transfers nutrients from the endosperm to the growing shoots and roots). The grain particles (endosperm, which is almost all starch) should be totally gone if you are doing a good job a mashing. This is why as your mash proceeds it gets easier and easier to stir.

The finer your crush, the smaller the initial starch chunks and the faster they disappear. There is a bit of confusion about milling fine, and stuck mashes. Some folks believe that all of the grain dust from a fine crush will result in a stuck mash. This is incorrect. The grain dust (aka flour) should disappear quite rapidly as it is converted to simple sugars. What can give you a stuck mash is if you crush the husk up too much, which one is more likely to have happen with a finer crush. It has nothing to do with the fine flour particles. Conditioning malts helps to keep the husks intact when doing a fine crush.

I make a beer that uses some homemade bread in the mash. I turn the bread into crumbs and they totally disappear during the mash. The bread is pure starch so it gets totally consumed