Beer Viking
Beer Lover
I thought that finding iodine on amazon would be simple but there seem to be a lot of different kinds. What is the right one for checking to see if I'm done mashing at an hour in?
Thanks!
Thanks!
What kind of iodine should I get to see if I'm done mashing?
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I think just the regular drugstore-type of iodine tincture is all you need
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Beer Viking
Beer Lover
Thanks. Do you use it yourself or just skip it?
I tried it once or twice early on just to see....
Used whatever drugstore iodine we had in the 1st-aid cabinet...
It works!
I don't bother anymore... I do BIAB with a "not quite full volume" mash ... So my crush is very fine, and my mash is pretty thin. Conversion is probably mostly complete in the first 20 mins. of my 60 min mash. In fact, if I'm running short on time, I'll only mash for 30-40min... Especially with a simple grain bill...
Edit to add:
Fine crush and thin mash both increase the enzymes' ability to convert starch to sugar by making more of the grain accessible...
Used whatever drugstore iodine we had in the 1st-aid cabinet...
It works!
I don't bother anymore... I do BIAB with a "not quite full volume" mash ... So my crush is very fine, and my mash is pretty thin. Conversion is probably mostly complete in the first 20 mins. of my 60 min mash. In fact, if I'm running short on time, I'll only mash for 30-40min... Especially with a simple grain bill...
Edit to add:
Fine crush and thin mash both increase the enzymes' ability to convert starch to sugar by making more of the grain accessible...
Betadine (tamed iodine or iodofor) also works.
if you have a feed store, they cary huge bottles of "titratable" iodine.....i think titratable is the key word, i have some methyl iodide for adding to my homemade lite salt... but it doesn't work for a starch test....
and i skip it, go by gravity. just wait till the hydro/refrac stops going up pulling samples from the mash tun.
If you are mashing good quality, well-milled, modern brewing malt IMO you don't need to do an iodine test, it is going to be converted. Stick your finger in the mash liquid and taste it. I can guarantee it is going to be very sweet. If you truly feel the need, as has been posted, iodine from the pharmacy will work just fine as does Iodophor sanitizer.
if it's cold enough for that, you might need an iodine test!
(but keep in mind only gel'd starch will indicate, which gets me thinking how effective it'd be for a adjunct batch. without a cereal mash))edit: i got to thinking about my idide for salt fortification, wait methyl iodide? isn't that a toxic gas, so i had to look, i forgot it's potassium iodide.
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if it's cold enough for that, you might need an iodine test!
I guess I have kitchen hands. A quick dip in 150F mash isn't a big deal. Unless you are using crazy amounts of adjuncts I doubt there would be much of a problem. I can only give you my anecdotal evidence but after doing a couple of iodine tests 30 years ago I quickly gave them up. My highest percentage adjunct mashes would be the occasional CAP with about 25% flaked maize and those have never been a problem.
jerrylotto
Well-Known Member
A better indication of conversion is your pre-boil gravity. Any unconverted starches will end up dropping out as trub anyway. As long as you have good pH and temperature control and allow sufficient time for the enzymes to do their thing, you should be in good shape.
On the other hand, iodophor is my go-to sanitizing solution and certainly will react with any residual starch on my gear.
On the other hand, iodophor is my go-to sanitizing solution and certainly will react with any residual starch on my gear.
Skip it. If there is a little debris in the test, they will be a false positive. If you kept your temp and time, it will be converted. We do 90 min mashes just to insure.
I’ve never tested mine. Just do 60 min mashes every time.
robert.balsinger
Well-Known Member
I use it only on my thickest mashes which do take longer. After you do the same mash several times and check for conversion you will be able to accurately predict where you are in the process. It is a useful tool when correctly done IMO.
I use Tincture of Iodine when I am with other people that are interested in the process. It is a good learning tool. That being said, I know my equipment and processes and only use it when I feel something is not quite right or I am using a new grain or very large grain bills.
VikeMan
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I'll just add that an iodine test only tells you if conversion is complete, i.e. that all the starches have been converted to sugars and dextrins. It tells you nothing about the relative fermentability of the wort. The longer the mash goes (within reason), the more fermentable the wort. Mash temperature and grain bill also play important roles in determening fermentability.
So, just mashing until you get a clean iodine test and stopping there probably isn't a good strategy, unless you're trying to keep fermentability as low a possible.
So, just mashing until you get a clean iodine test and stopping there probably isn't a good strategy, unless you're trying to keep fermentability as low a possible.
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Beer Viking
Beer Lover
Great information guys! I think I'll skip it altogether and just do 90 min mashes unless 60 would be fine?
60 is fine
It becomes more of an issue if you're mashing with a lot of adjuncts, and/or your base malt has low diastatic power. Otherwise, the vast majority of conversion is complete in about 20 minutes. In 60 minutes, you should be fine.
I strongly agree that monitoring the SG of the wort in the mash is the best test for determining percentage of conversion. This is best done with a refractometer, as the samples are only a few drops, and cool quickly to a testable temp. I have attached spreadsheets below that show max possible wort SG vs. mash thickness (qt/lb) assuming a grain potential of 80% (1.037), which is close enough for most typical mashes that are less than ~10% crystal, roast, etc. Approximate formulas for percent conversion (i.e. conversion efficiency) are:
% Conversion = 100% * Measured °Plato / Max °Plato
% Conversion = 100% * (Measured SG -1) / (Max SG -1)
These formulas are most accurate near 100% conversion, and get less accurate as the % conversion goes down.If the grain bits in the sample fail the test, that means you still have unconverted starch in the grain bits - the mash isn't "done." Any soluble starch that is in the wort only lasts a few minutes at most before it is reduced to fragments short enough to pass the test (assuming you still have adequate enzyme levels in the wort.)
Brew on
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Beer Viking
Beer Lover
If I wanted to do a Kölsch or a hefeweizen would 60 still be ok?
Those brews should be fine as the base malts used tend to have a high DP.
A base malt generally needs a DP above about 35 or 40L to self-convert in the mash. If you have a large percentage of adjuncts, the base malt needs to be higher, to provide enough enzymes to convert those adjuncts.
https://www.brewunited.com/grain_database.php
The amount of time it takes to get full conversion depends on the milling of the grain. You can get full or nearly full conversion with whole grains but it takes lots more time than finely milled grains. Research how Crystal malts are made.
Like everyone else, I tried the iodine test once or twice in the 80's when I did my first whole grain brews and then never again. Also as said above, you might like the result of mashing a little longer than just completing conversion. I usually mash 60 min or if the crush I get from MoreBeer is a little on the coarse side, I will go for 75-90 minutes. Some folks are even mashing overnight, so there seems to be a wide time range you can experiment with.
I made a pilsner back in 2019 and I was getting significant SG changes into the 90 minute period.
https://ethanolwork.com/2019/05/11/mash-experiment-pilsner/
https://ethanolwork.com/2019/05/11/mash-experiment-pilsner/
How is "thin" your mash? What is ratio grist to water (approx)?
I do BIAB with *almost* full volume mash... 6 Gal batches.. So for my 12-15ish lb grain bills I do roughly 8 g total water.... I jigger my mash volumes (using Brewtarget brewing software) so that I have about 6.5 gallons of strike, and 1.5 gallons of dunk sparge in a separate smaller kettle...
It works out to about 2.25 -2.5 quarts/lb depending on grain bill, etc.
I think the math works out better to do 2 equivalent runoffs... (i.e.strike - loss=1st run off. 2nd runoff about equal to 1st, adjust as required) but it's more convenient for me to use a 1.5g dunk... So that's
what I do....
The exact ratio isn't critical, but you can find some theoretical plots on here, that show the max extraction for various sparge scenarios... @doug293cz has done them I think...
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Correct, exact run-off volume ratio is not critical for getting near optimal lauter efficiency when batch sparging. Anywhere from 60:40 to 40:60 will give results that you won't be able to detect the difference between. Here's a graph from Kai Troester (Braukaiser) that shows how lauter efficiency varies with run-off volume ratio. 0 is no sparge, and 0.5 is equal run-off volumes. The graph also shows how lauter efficiency varies with grain bill size assuming the same pre-boil volume for all cases.
Here's my chart that shows how lauter efficiency varies with number of sparge steps, grain absorption rates, and grain weight to pre-boil volume ratio:
Brew on
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