iodine test and SG

[shark_sandwich]

mashing as I type one question.
at 45min took reading of ph and sg and iodine
my sg was 1.068 and iodine indicated that conversion was complete then at 1 hour sg was up to 1.071 and then at 70 min was at 1.074.

how come my sg keeps going up after iodine said that conversion was complete?

 

[Beer is good]

mashing as I type one question.
at 45min took reading of ph and sg and iodine
my sg was 1.068 and iodine indicated that conversion was complete then at 1 hour sg was up to 1.071 and then at 70 min was at 1.074.

how come my sg keeps going up after iodine said that conversion was complete?

I am interested to see the replies to this as well. I never check my gravity when mashing, I only check iodine. Your post makes me wonder if I should also be checking gravity.

 

[craigmw]

Maybe because a longer mash leads to further extraction of sugars/starches from the grain? I've seen plenty of posts boasting about complete conversion in 10 minutes of mashing, but I think extended mashes tend to give better extraction simply through solubilization of starches from the grains, which are subsequently converted to fermentable sugars. Your observation is another argument for longer mash times.

 

[Beer is good]

Maybe because a longer mash leads to further extraction of sugars/starches from the grain? I've seen plenty of posts boasting about complete conversion in 10 minutes of mashing, but I think extended mashes tend to give better extraction simply through solubilization of starches from the grains, which are subsequently converted to fermentable sugars. Your observation is another argument for longer mash times.

That make sense. More time for the good stuff to seep out of the grain.

 

[RM-MN]

When you used the iodine you probably tested a drop of wort which contained no starches. Had you included some grain you probably would have shown the presence of starch in the grain. With continued mashing you were able to convert some of that starch which then added to your gravity. With the fine grind I do on my grain because I can with BIAB, there is no indication of starches in the grain within a short period. In other words, small particles wet through faster, convert faster, and leach the sugars out faster.

 

[TexasWine]

Maybe because a longer mash leads to further extraction of sugars/starches from the grain? I've seen plenty of posts boasting about complete conversion in 10 minutes of mashing, but I think extended mashes tend to give better extraction simply through solubilization of starches from the grains, which are subsequently converted to fermentable sugars. Your observation is another argument for longer mash times.

I did a 30 minute mash last brew. Overshot my OG, and finished out below my expected FG. We're seeing evidence that long mashes aren't necessary for a lot of brews that we do. I'd recommend trying it and posting your results. Remember to crush very, very fine!

But, back to why the OP was seeing an increase in gravity. Were you using a refractometer or hydrometer? If using a hydrometer, did you cool the sample to the same temp each time before taking the measurement? Did you give everything a good stir before pulling the sample?

Your gravity could also be continuing to rise becasue, well, it is rising! If you didn't get a good crush and had a lot of grain intact then it's gonna take a long time so soak that kernel through and through.

Hope this helps!

 

[shark_sandwich]

I thought that I read somewhere that when doing an iodine test that you don't want grain particles in there?

At that point I was using a refractometer and as far as stirring I run a herms system so once the I mash in I don't do any stirring unless something goes wrong.

I was doing some reading and ran across this:http://www.woodlandbrew.com/2012/11/top-ten-reasons-why-your-final-gravity.html
7) Mash time too short.

Even after conversion from starch to sugar is complete the beta enzymes will continue to break down the long sugar chains into shorter ones. Mashing at 150 for 60 minutes will produce a less fermentable mash than mashing at the same temperature for 90 minutes. To control your wort's ferment ability you will want to add a mash out step at 165-170 to denature the enzymes.

 

[RM-MN]

I thought that I read somewhere that when doing an iodine test that you don't want grain particles in there?

At that point I was using a refractometer and as far as stirring I run a herms system so once the I mash in I don't do any stirring unless something goes wrong.

I was doing some reading and ran across this:http://www.woodlandbrew.com/2012/11/top-ten-reasons-why-your-final-gravity.html
7) Mash time too short.

Even after conversion from starch to sugar is complete the beta enzymes will continue to break down the long sugar chains into shorter ones. Mashing at 150 for 60 minutes will produce a less fermentable mash than mashing at the same temperature for 90 minutes. To control your wort's ferment ability you will want to add a mash out step at 165-170 to denature the enzymes.

You don't normally want the grain particles because they usually show starch even though the wort tests negative. By mashing longer you continue to convert that starch left in the grain particles until all is converted or until the water can no longer reach the starches. With that said, with the very fine particles I use, even the grain tests negative for starch.

 

[billl]

Iodine tests for starch. For it to test positive, there needs to be starch in solution you are testing. However, not all of the starch goes into solution instantly. The bigger the particles, the longer it takes.

So, iodine only tests to make sure you have decent wort that will ferment at normal levels. It doesn't indicate whether you've gotten 100% of the available sugars converted.

 

[MEPNew2Brew]

Unless you mash for a very long time, or crush very fine, you will just about always have starch if you check pieces of the grain, rather than just the liquid. I am in the middle of mashing. I just did iodine. Wort was fine. Grain pieces were black. Mash temp dropped way too much during mash. So, I added 1 gallon 180 water to bring it back up to 148.5. Letting it sit for 20 mins. Will report back in a bit as to what grain pieces did on second iodine test.