[rbclay]

i'm doing a large mini-mash, if that makes any sense. adding 50% extracts (3.15# Munich LME, 3# Extra Lt. DME, 1/2# corn sugar) in addition to this grist:
2lbs. Munich
1lb. dark Munich
14oz. Caramunich
8oz. chocolate
2oz. each Aromatic and Carafa II.
 
my question is this- will an iodine conversion test give a "false" positive when there are specialty grains - already coverted- in the grist? My understanding is the 3# of munich malt needs to be converted. so far, at 30min into the mash started at 156F and now at 150F, an iodine test says it's converted. i'm continuing with a 60min mash, then sparge.
the mash had 1.5G water, sparged with 2.5G water @ 170F to yield 3.25G in kettle at 1028SG.
 
is this good? according to Palmer's efficiency calculations it's not. 28pts x 3.25G / 4.625 lbs of grain = 19. Palmer says shoot for 27-30. Below 25 is poor. We'll see how many points my OG is off.
Target OG 1069. Actual 1064. I suppose that loss was mostly from the "poor" mash?!?
 

[hopfenundmalz]

The iodine test will tell you if you have starch.  It does not tell you how fermentable the wort is.  You can have dextrins that won't ferment.  Let it go for the hour.

Munich will convert itself.  Dark Munich will just convert itself.  If you didn't dilute the enzymes too much, you should be OK.  The iodine test says you are on your way.

[denny]

Personally, I don't see much value in the iodine test.

[euge]

Me either. I have a mini-mashtun, about 2 gallons. Never had any sort of grain bill fail to convert. If you did a single sparge then I would expect a lower efficiency than if you had batch-sparged. I get about 76% from my little tun when I batch-sparge. About 60% when it's a no-sparge.

[a10t2]

is this good? according to Palmer's efficiency calculations it's not. 28pts x 3.25G / 4.625 lbs of grain = 19. Palmer says shoot for 27-30. Below 25 is poor.

Rule out simple things first. Make sure you're crushing well and that your instruments are calibrated. With this being a mini-mash, my next suggestion would be to evaluate your sparging technique. Make sure that whatever you're doing is getting all the sparge liquor in complete contact with all the grains.

The next thing too look at would be pH. With this mash having a large amount of dark roasted malt, if you used really low-alkalinity water you could have pulled the mash pH down far enough out of range that 60 min wasn't enough time for full conversion. Do you know your water chemistry? Did you check the mash pH?

Munich will convert itself.  Dark Munich will just convert itself.  If you didn't dilute the enzymes too much, you should be OK.  The iodine test says you are on your way.

I agree that this particular mash was probably fine, but you need to be careful about generalizing when it comes to Munich malts. Light Munich can be as low as 60-80 L, and Dark Munich much lower. In that case 2 lb of Munich wouldn't necessarily convert 2.5 lb of other malts - at least not quickly.

As Denny mentioned, an iodine test isn't necessarily easy to perform and interpret.

[hopfenundmalz]

is this good? according to Palmer's efficiency calculations it's not. 28pts x 3.25G / 4.625 lbs of grain = 19. Palmer says shoot for 27-30. Below 25 is poor.

Rule out simple things first. Make sure you're crushing well and that your instruments are calibrated. With this being a mini-mash, my next suggestion would be to evaluate your sparging technique. Make sure that whatever you're doing is getting all the sparge liquor in complete contact with all the grains.

The next thing too look at would be pH. With this mash having a large amount of dark roasted malt, if you used really low-alkalinity water you could have pulled the mash pH down far enough out of range that 60 min wasn't enough time for full conversion. Do you know your water chemistry? Did you check the mash pH?

Munich will convert itself.  Dark Munich will just convert itself.  If you didn't dilute the enzymes too much, you should be OK.  The iodine test says you are on your way.

I agree that this particular mash was probably fine, but you need to be careful about generalizing when it comes to Munich malts. Light Munich can be as low as 60-80 L, and Dark Munich much lower. In that case 2 lb of Munich wouldn't necessarily convert 2.5 lb of other malts - at least not quickly.

As Denny mentioned, an iodine test isn't necessarily easy to perform and interpret.

So you missed the caveat about not diluting too much?  The Iodine test just says no starch, period.  It says nothing about what the composition of the wort is. 

I agree with Denny, to a point.  Maybe he should ask the brewers at Sierra Nevada why they do Iodine tests when he is at Beer Camp?

[a10t2]

So you missed the caveat about not diluting too much?

Nope, just misinterpreted it. I thought you were talking about using too thin a liquor:grist ratio.

[hopfenundmalz]

So you missed the caveat about not diluting too much?

Nope, just misinterpreted it. I thought you were talking about using too thin a liquor:grist ratio.

I just got back on to say that I want to make sure that one should think about the amount of enzymes in the mash.  You can do some quick calculation to make sure the weighted average degees lintnes is high enough to assure conversion.  with that being said, unless you have the lot analysis for the bag of grain, let us say Durst Dark Munich, you may run into problems using the average published numbers.  I had one bag that was problematic for a Doppelbock.  The Iodine test said it was not converted, though it look pretty good to the eye.  More time and boosting the temp  to 158 got it to convert.

I was at Beer Camp 2 years ago.  Scott Jennings, the head pilot brewer, did an Iodine test on the mash.  I asked why.  He said it sometimes catches a problem, and is quick and easy.  I had not done one in 10+years, but started doing those since.  That is how I caught the conversion problem on the Doppelbock.  We all need to evaluate our procedures, and think about what they tell us, adn don't tell us.


 

[Jimmy K]

With modern high diastatic power malts, mashs can convert in 20 minutes. But there was a recent Zymurgy (I think) article saying that longer mashes as still ideal because there are other reactions going on than simple starch conversion. Longer mashes become more fermentable as dextrins are cut into simpler sugars.

[rbclay]

Rule out simple things first. Make sure you're crushing well and that your instruments are calibrated. With this being a mini-mash, my next suggestion would be to evaluate your sparging technique. Make sure that whatever you're doing is getting all the sparge liquor in complete contact with all the grains.

Got that covered. I'm taking baby steps into AG. I have a 10gallon rubbermaid with a false bottom. Rather large for <5lbs grain, but it makes it very easy to sparge "by hand" using another 5gallon cube cooler with a hi-heat tube with one of those white aerator ends on it. Definitely soaking all the bed.

The next thing too look at would be pH. With this mash having a large amount of dark roasted malt, if you used really low-alkalinity water you could have pulled the mash pH down far enough out of range that 60 min wasn't enough time for full conversion. Do you know your water chemistry? Did you check the mash pH?

Good water with pH in the 5.0-5.4 range. But I did not check the pH during or after the mash. Next time I will do that for certain. I have the cheap pH strips, but that is good enough for now.

[rbclay]

Me either. I have a mini-mashtun, about 2 gallons. Never had any sort of grain bill fail to convert. If you did a single sparge then I would expect a lower efficiency than if you had batch-sparged. I get about 76% from my little tun when I batch-sparge. About 60% when it's a no-sparge.

This is where I believe I left a few points in the mash tun. I only sparged with 2.5gallons of water, resulting in 3.5 gallons in my kettle. If I had sparged with another 4-6 quarts I probably would have extracted more.

If you "no sparge", you are only collecting what you mashed with, correct? If you "batch" sparge you let the bed drain, then add more water, correct? "Fly" sparge was just called sparging until Denny came along and called his technique "batch", right?!? I was going for continual, or "fly", or just plain sparging!

[Jimmy K]

^^^
That's correct.

[denny]

"Fly" sparge was just called sparging until Denny came along and called his technique "batch", right?!?

Well, in t he interest of complete info, I didn't invent it...I'm not that smart!  I learned about it from George Fix, Ken Schwartz, and Bob Regent (anybody around SF know whatever happened to Bob?).  I just took their info and ran with it.  I like d the technique so well I started talking it up on the internet.  Now look what's happened!

[weithman5]

 I'm taking baby steps into AG.

dive in, my friend.  i did one extract kit, a lager, then dove in to all grain.  at least for me it was easier to work on refining this process than working on refining a changing process.  (that said, i have been thinking of doing a few extracts again)

[rbclay]

i'm only hesitant to do all-grain because i have spent so long "perfecting" my mini-mash recipes/system. i stubbornly stuck with extracts 4 years ago when i joined a club in order to become a better brewer. i have become a much better brewer and kept extracts as my base. i was honored this year with a silver at Nationals with a Brown Porter that is 52% extract! that porter and my APA (72%extract)  both qualified for MCAB this year. i know that winning medals isn't the end all and be all of brewing, but it does feel pretty cool to enter a contest for feedback and have that feedback accompanied by awards!

part of me wants to continue buying the 55lb. boxes of Munton's Extra Light DME that i've been buying for years, but part of me says screw it, buy a bigger kettle with a faucet and another cooler HLT/tun and don't look back...

thoughts?!?