I’m having trouble getting full starch conversion

[Steve Broady]

I’m sure I’m doing something wrong, but I’m not sure what. Hopefully someone here can point me in the right direction.

Every time I try to make an all grain mash, I end up getting only partial starch conversion (according to an iodine test). I’ve tried using powdered amylase enzyme in the ratio recommended on the package and at double or triple concentrations, and using malted barley as roughly 1/4 of the grain bill. In each case I get some conversion, enough to make alcohol, but never what I think I should be getting. When I make rum, UJSSM, or a sugar head using spent grain, I get roughly 1.5 gallons of low wines out of a 5 gallon ferment, run out to about 5-10% ABV. I usually get around 1 gallon of low wines from a grain mash that (according to my calculations and a couple different apps I’ve tried) should yield about the same gravity as the sugar recipes I’ve used.

My technique: If I’m using corn, I’ll boil that to gelatinize the starch. I typically put it in the oven to hold at about 200F for 2-3 hours. Next I bring the temperature down to 150F by adding cold water/ice, after which I’ll add any cooked grains, barley, or enzymes. I’ll put that in the oven at 170F (the lowest my oven will go) to sit for 90-120 minutes. I’ve also tried just letting it sit on the stove top, and raising the oven temperature to 180F (because at 170 my IR thermometer was reading 143F when I stirred the mash), but I get the same results either way.

On the theory that the enzymes should continue to work at room temperature, just more slowly, I’ve also simply let the ferment go longer, up to a month or so. It still failed the iodine test at that point, so I gave up and distilled it.

I will say that the flavor has been great, and the yield isn’t so low as to make it pointless, but I feel like I’m missing something. I recognize that my equipment isn’t as good as some people’s (I’m working in an 8 gallon pot on the stove or oven, and my thermometer is pretty cheap), so maybe that’s it? But my gut tells me that I’m missing some critical technique. I have considered making a copper heating coil which I could put into the pot and pump hot water from a sous vide though it.

Any help would be greatly appreciated. Or maybe I’m just asking for too much out of my setup. If so, it would be nice to know as well. Thanks!

[Deplorable]

The first thing I would do is verify your thermometer. Then I'd buy a hydrometer. (Assuming you don't have one since you didn't give details about your OG or FG)
A little more information about your mash bill would be helpful to determine what might be your (perceived) problem. If you're working with feed store corn rather than corn meal, that could account for a lower yield. I can consistently achieve an OG of 8.5 to 9.5% using 2.3 pounds of grain per gallon of water, and high temperature enzymes in the corn while gelling.
Even a small ferment in 5 to 10 gallon buckets should hold enough heat wrapped in blankets to let the enzymes in the malts work on the gelled corn without an outside heat source.
If you're cooking your corn for 2 to 3 hours at 200, then letting it cool to 150 before adding your malts, you should be getting a good conversion.
Are you sure that you do not have solids in your pulled sample for the iodine test?

[bluc]

Do you adjust the ph of the mash water? I found it made a pretty big difference.
What is your mash thickness and sg reading?

[Steve Broady]

[quote =Deplorable post_id=7722442 time=1661643159 user_id=80348]
The first thing I would do is verify your thermometer. Then I'd buy a hydrometer. (Assuming you don't have one since you didn't give details about your OG or FG)
[/quote]

When I first got the thermometer, I verified it with ice water and boiling water, but I haven’t checked it since then. I know that battery voltage can affect things like digital calipers, so maybe that’s a problem here as well.

I do have a hydrometer, but I generally don’t bother with it on the all grain mashes. For one thing, since I’ve only tried fermenting on the grain, the mash is so thick that I don’t trust the reading I’d get. Also, since I more or less assumed that the fermentation and conversion were going to have to run concurrently, I figured it wasn’t worth taking an initial reading like I had been doing for everything else. Lastly, I’ve just figured that I’d distill whatever I got once the yeast were done and showing no more activity. Not the most useful technique for troubleshooting, I realize.

[quote =Deplorable post_id=7722442 time=1661643159 user_id=80348]
A little more information about your mash bill would be helpful
[/quote]

My latest recipe is 8 lbs of milled corn from Tractor Supply, 1 2/3 lbs of flaked rye, and 3 1/3 lb of 2-row barley, in 2 gallons of backset and 3 gallons of well water. Part of an experiment I’m running, but that’s another story.

[quote =Deplorable post_id=7722442 time=1661643159 user_id=80348]
Are you sure that you do not have solids in your pulled sample for the iodine test?
[/quote]

No, I’m not at all sure, nor was I aware that that could be a problem. What I’ve been doing was to separate out a little of the liquid, put it in a small glass bowl, and then add a couple drops of iodine from the drug store. Seeing it turn black makes me assume that I still have a fair bit of starch present.

[Steve Broady]

Do you adjust the ph of the mash water? I found it made a pretty big difference.
What is your mash thickness and sg reading?

I do not check the pH, because I don’t know what the target would be anyway. My well water is slightly acidic (6.5, if I remember right from my aquaponics days), and I usually add a gallon or two of backset, which I understand should also lower the pH.

When I cook the corn, the mash is incredibly thick. I use a corded drill and a 5 gallon cement mixer to stir it, and it takes some force just to keep the drill from turning in my hand. As soon as I add the barley or the amylase, it thins out drastically. It also gets noticeably sweeter. And it ferments so I know I’m getting SOME conversion.

[still_stirrin]

My technique:

If I’m using corn, I’ll boil that to gelatinize the starch. I typically put it in the oven to hold at about 200F for 2-3 hours. <— That’s a good process. To reiterate, only the corn needs this process.

Next I bring the temperature down to 150F by adding cold water/ice, after which I’ll add any cooked grains, barley, or enzymes. I’ll put that in the oven at 170F (the lowest my oven will go) to sit for 90-120 minutes.
I’ve also tried just letting it sit on the stove top, and raising the oven temperature to 180F (because at 170 my IR thermometer was reading 143F when I stirred the mash), but I get the same results either way. <— Too hot! You’re denaturing the gluco-amylase enzymes. Don’t hold the temperatures above 150*F.

On the theory that the enzymes should continue to work at room temperature, just more slowly, I’ve also simply let the ferment go longer, up to a month or so. It still failed the iodine test at that point, so I gave up and distilled it. <— OK. So, time helps the enzymes work, provided you haven’t denatured them already (see comment above).

Any help would be greatly appreciated. Or maybe I’m just asking for too much out of my setup. <— It’s not “the equipment” failing here. It’s your brewing skills. Some time spent on a homebrew website forum might actually help you a lot.

So, gelatinization of the corn is critical to its conversion. Always mill your corn to a moderately fine cornmeal (not flour) but well ground to a cornmeal consistency. Your technique for gelatinization sounds good (I use the oven set at 200*F for 2-3 hours too). That time allows me to get the mash water to proper “strike temperature” for the barley malts and other grains.

Then, I dough the malts in into the mash tun, and then mix in the “corn pudding” from the oven, being careful to keep the temperature of the mash mix at 148-152*F. I use hot or cold water to adjust as necessary to manage the temperatures. But I hold the temperature consistent, stirring regularly, until I get a negative iodine test. This can take an hour, two, or more. You’ve got to be patient with this. It’s your duty as a brewer. Some distillers even wrap their fermenters in insulation and “tuck it in for night”, giving the mash 4 to 8 hours to convert. The “pay off” will be discovered in your boiler when you run it.

Time … it’s not just something that passes … it’s the foundation of your future!
ss

[shadylane]

Every time I try to make an all grain mash, I end up getting only partial starch conversion (according to an iodine test). I’ve tried using powdered amylase enzyme in the ratio recommended on the package and at

Get some high temp alpha amylase.
https://moonshinedistiller.com/sebstar- ... me-master/

[Steve Broady]

Thanks for the advice, guys. Sounds like I still have a bit of learning ahead of me. Shocker, right? Who knew that you can’t just jump in and have perfect success the first time around?

Still-stirrin, to clarify a little I am not trying to hold the mash above 150. Every time I measure the temperature of anything that’s cooking slowly in the oven, it seems to stay well below the set temperature. I assume this is due to evaporative cooling. With the oven set to 170, I measured 143. And in any case, I haven’t seen a significantly different result between just letting the mash sit unheated and keeping it warm in the oven. From that, I guess that denaturing the enzyme isn’t my main issue, though it’s definitely something I’ve been concerned about. But your point is taken, it is something I need to be careful about. While my average temperature might be 150, I could definitely have localized overheating. That was part of my reasoning for thinking about a sous vide based heating coil.

[Ben]

I'm not sure what your batch size is, but a simple cooler (like for camping) could really save you a bunch of work. Heat and gel your corn in the oven as you have been, then put it in a cooler, add enough cool water and your grains to hit mash temp, let sit in cooler until conversion is done. You can find a strike temp calculator on the internet to help. Even a super basic wal-mart grade cooler will usually lose less than 2° per hour. When done transfer to fermenter.

[Deplorable]

Keep at it Mr Broady.
One thing you might try is thinning out your mash a bit to 2 pounds per gallon and see if it improves your conversion any.
I'd also 2nd the above suggestion to get some alpha Amylase to help break down the long chain starches in the corn prior to adding in your malted barley.
They'll also make stirring the corn porridge less of a task.

[bilgriss]

Part of the enzymatic conversion process, be it at mash temperature or later at cooler ones, is the availability of starch to the enzymes. That is to say, if the mash is too thick, starches still locked in corn where it hasn't gelatinized yet, or enzymes denatured by high temps, there's starch that isn't being directly exposed to liquid and enzyme. So you will continue to have starches appearing in your mash that haven't been converted. A thinner mash makes starches more available, and also makes it easier for liquid to penetrate any "chunks" which haven't yet been exposed.

Good suggestions have been made. Start with a high-temp enzyme addition to thin out the corn when gelatinizing. Makes it much easier to stir, and makes liquid more available - speeds things up. Bring your temperatures down to where enzymes aren't being denatured when malt is added. If the temperature isn't dropping to 145 or less when you add the malt, you might considering adding at a slightly lower temperature. The higher you add, the faster enzymes denature. They only keep working at lower temps if they are there. We've had members in the past who have even preached mashing at low temperatures like 135 for longer. That's not standard for most of us, but it demonstrates that it's less of a concern to keep your temperature up than to not have it too high.

Finally, there's rarely "perfect" conversion visually, if you leave the ferment on the grain. That is, some small amount of starches continue to be released, and hopefully be converted, but you could in theory get a non-negative iodine test at any point in the process. If the mash is fully converted and you remove it from the grain, it will 'finish' and stay that way usually. Lots of us will get a negative iodine test consistently, but sometimes you might not.

Reading, experience, and above all patience will get you through this one.

[Twisted Brick]

Do you adjust the ph of the mash water? I found it made a pretty big difference.
What is your mash thickness and sg reading?

I do not check the pH, because I don’t know what the target would be anyway. My well water is slightly acidic (6.5, if I remember right from my aquaponics days), and I usually add a gallon or two of backset, which I understand should also lower the pH.

---------------------------------------------------------------

My latest recipe is 8 lbs of milled corn from Tractor Supply, 1 2/3 lbs of flaked rye, and 3 1/3 lb of 2-row barley, in 2 gallons of backset and 3 gallons of well water. Part of an experiment I’m running, but that’s another story.

I may be off base here, but IMO you've thoroughly stressed your enzymes. Enzymes work best in their recommended range of pH, not just temps. 2 gallons of backset is what, 40% of your strike water? You're starting with acidic water, add backset, and then your grains drop the pH even further. In contrast, I use 1 qt of backset in 12.5gal mashes that start out with 7.0 water. After conversion is complete the mash (in time) stratifies leaving a layer of clear golden liquid from which to take gravity readings.

Approaches like yours of why you're not checking pH, nor recording starting and finishing gravities is only making your task more difficult to troubleshoot.

[shadylane]

My latest recipe is 8 lbs of milled corn from Tractor Supply, 1 2/3 lbs of flaked rye, and 3 1/3 lb of 2-row barley, in 2 gallons of backset and 3 gallons of well water.

40% backset, that's way too much.

[Deplorable]

If your well water is already 6.5 and 40% of your strike water is backset, and you arent checking the pH of your total strike water, how do you know if you are working within the optimal pH range for your malts diastatic enzymes?
I agree with TB, you're creating a hostile work environment for your malts. Too thick, too acidic, and likely too hot.

My tap water is a pretty consistent 7.0, and I don't need to use any backset to drop the pH to around 5.5 to 5.8 other than add grain. Usually, the process of gelling the corn gets me to around 6 to 6.3, and by the time I've reached full conversion (usually 90 minutes after adding malts) I'm sitting around pH of 5.5 and there is about a 4 to 6 inch layer of clear amber liquid to pull a sample from for testing pH, OG, an iodine test, and feed my yeast starter while I use a wort chiller to crash to pitching temps and aerate the mash.

My standard process for gelling corn in large batches is to add boiling water to corn meal at 2#/G, wrap and rest for 3 to 4 hours stirring every 45 minutes or so with a mortar mixer, add Alpha Amylase at the recommended temperature and stir it into the top 3 inches and let rip its way through, continuing to stir every 40 minutes or so for a couple more hours.
Add cool water to bring the temp down to strike temperature and add my malts. Stirring them in to prevent dough balls. Wrap and rest for 90 minutes. Then I verify conversion, add any remaining water to bring the mash to the target volume or OG, chill, and pitch yeast.

[shadylane]

Here's how I'd do your recipe.

I'd mix SEBSTAR HTL in 4 gallons of water.
Put the 8lbs of milled corn in your pan and mix the water into the corn.
Set the oven temp to around 180f and put the pan in the oven.
Wait and stir.

After a couple hours, turn off the oven and add a quart of frozen backset and a gallon of cold water.
When the temp is under 150, add the rye, malt and SEBAMYL GL
Leave the pan in the oven while the mash is cooling to yeast temp.

[BlueSasquatch]

I used to be a big fan of Iodine test but have shifted more into running a Home-Brewer's Calculator on the content of the mash, to give me a target SG to hit, and then take readings during the mashing process to get a better gauge of where I am at. After a long rest at temp, things have settled enough that you can do a light stir of the middle liquid, without disturbing the solids, and then pull a sample jar. The home-brewers calcs also tend to push that 75% conversion is good, and shooting for "100% conversion" is a losing battle.

For mashing, look no further than beer gurus, they have it down. (Ignore their bit about a post-boil)


Poor conversion for my all-grains always comes back to: Not enough rest time at temp. - Better insulation and left alone for longer.

[still_stirrin]

… The home-brewers calcs also tend to push that 75% conversion is good, and shooting for "100% conversion" is a losing battle…

Good point, Sasquatch.

I run the calcs using a 75% mash efficiency, which includes losses due to lautering (which I do). The calculator gets me close to my target OG at runoff, but factors can influence my extract, such as: runoff speed, saccarification rest time and temperature, and even the water to grain ratio (liquid or a “stiff” mash). All those considerations are a “part of the art” we (homebrewers) use to create our signature beers.

… Poor conversion for my all-grains always comes back to: Not enough rest time at temp. - Better insulation and left alone for longer.

One thing that will help conversion too, is gentle agitation. If you stir periodically, that helps. But a constant, low rate agitation, ala RIMS (recirculation infusion mash) will keep the enzymatic activity vigorous as the starches are converted. Nobody said brewing was easy, right?
ss

[StillerBoy]

Poor conversion for my all-grains always comes back to: Not enough rest time at temp. - Better insulation and left alone for longer.

That has also been my experience, as my process takes about 6 -8 hrs to go from 185 to 140*F, at which time gluco is added and allowed to cool over night to pitching temp.. I also do stir every 30 - 45 min for the first 2.5 hrs, and also every 30 min between 120 - 140.. and all my mashes by pitching time have been very liquidy, as the gluco does increase/improve the liquidy of the mash,but does required time.. most beginners rush the process, and have also notice that using a wort cooler, wanting to cool it to fast especially the gluco phrase, has reduced the liqiudy effect..

Mars

[Steve Broady]

I have to say, you guys are awesome. I appreciate the comments, advice, and especially anyone pointing out where I'm going wrong.

Regarding backset, I've seen a number of recipes that call for 25-50%. I arrived at 40% because it's somewhere in between those numbers, and because this is only gen 3 of the recipe. When I've made UJSSM, I slowly tapered off the percentage as the generations increased, down to about 20-25% after gen 6 or 7, and was getting great results. But, I was also getting great results at 40% with gen 3 back then as well. Granted, I didn't account for the effect of the grain itself. I didn't really think about it being acidic on its own.

I've got pH test strips. Sounds like some testing is in order. Ad I got into this hobby, I bought a fair bit of the basic testing equipment, but for the most part in the moment I've just been going with it unless I had a problem that I was trying to diagnose. Mainly because in my day (or night) job, I have to be so ridiculously careful to follow every rule to the letter than when I have a rare moment to breathe and think about making something tasty, I just want to relax and let nature take its course. I think maybe I've taken that a bit too far at times.

Moving forward, it seems like I have a few things to consider. One is not to expect perfection, to be honest. Another is to take a little more time, as it sounds like I'm making the process a bit more complicated than it needs to be. And finally, do more testing along the way to better asses whats going on at each step.

[BlueSasquatch]

One thing that will help conversion too, is gentle agitation. If you stir periodically, that helps. But a constant, low rate agitation, ala RIMS (recirculation infusion mash) will keep the enzymatic activity vigorous as the starches are converted. Nobody said brewing was easy, right?
ss

Right, I have in the works, three kegs to convert to mash tuns (and to use as fermentors as well) which I plan to use the 2" ferrule on top, to mount a small agitator, to allow for a slow agitation during the entire rest cycle, while being heavily insulated. Perhaps I'll find it better to only agitate for 2 minutes every 20 or something, but it opens up the option for a number of possibilities, without losing unneeded heat from opening up to paddle-stir. Will be looking at some sort of large insulated Keg condom for lack of a better term. To see how little of a heat loss I can get. My home brewer friend keeps going on and on about his insulated drink cooler being superior.

That has also been my experience, as my process takes about 6 -8 hrs to go from 185 to 140*F, at which time gluco is added and allowed to cool over night to pitching temp.. I also do stir every 30 - 45 min for the first 2.5 hrs, and also every 30 min between 120 - 140.. and all my mashes by pitching time have been very liquidy, as the gluco does increase/improve the liquidy of the mash,but does required time.. most beginners rush the process, and have also notice that using a wort cooler, wanting to cool it to fast especially the gluco phrase, has reduced the liqiudy effect..
Mars

I've been leaning towards no-corn all-grain batches lately, which peak at say 155-160 degrees, I usually shoot for 1-2 hours at rest, once the SG reading is satisfactory, I try to cool it down as quickly as possible. I've waited overnight to pitch but seems like I get a 20% infection odds when I wait overnight. I'm not wanting to remove grain, and immersion chillers just don't float my boat.

[Twisted Brick]

I have to say, you guys are awesome. I appreciate the comments, advice, and especially anyone pointing out where I'm going wrong.

Regarding backset, I've seen a number of recipes that call for 25-50%. I arrived at 40% because it's somewhere in between those numbers, and because this is only gen 3 of the recipe. When I've made UJSSM, I slowly tapered off the percentage as the generations increased, down to about 20-25% after gen 6 or 7, and was getting great results. But, I was also getting great results at 40% with gen 3 back then as well. Granted, I didn't account for the effect of the grain itself. I didn't really think about it being acidic on its own.

Yeah, the legacy recommendations calling for 25% backset are exactly that: old and outdated. Today's distiller has a raft of measuring tools that beg to be utilized to ensure strict quality control. Since every distiller's water is different, measuring variables is a prudent exercise indeed. A started out adding a gallon (12.5gal mash) of backset, but saw diminishing conversion rates over the course of successive batches due to the increasing acidity of re-used backset. Now I store quart jars of fresh backset in a spare fridge, some wheat-based, rye-based and corn-based.

[StillerBoy]

I've been leaning towards no-corn all-grain batches lately, which peak at say 155-160 degrees, I usually shoot for 1-2 hours at rest, once the SG reading is satisfactory, I try to cool it down as quickly as possible. I've waited overnight to pitch but seems like I get a 20% infection odds when I wait overnight.

The mashing method differences in that you mash at lower temp than I do, even if no corn is used.. all my mashing without corn are done at 175 - 180*F, say like raw rye and some other malted gains are all done together, and all my mashing have all been using liquid enzymes, as I never relied on nature conversion due to the infection threads I've read, so I never experience an infection, and I account that to mashing to higher temp.. as to the finished product, they've all turned out well, but there could be differences..

Mars

[BlueSasquatch]

The mashing method differences in that you mash at lower temp than I do, even if no corn is used.. all my mashing without corn are done at 175 - 180*F, say like raw rye and some other malted gains are all done together, and all my mashing have all been using liquid enzymes, as I never relied on nature conversion due to the infection threads I've read, so I never experience an infection, and I account that to mashing to higher temp.. as to the finished product, they've all turned out well, but there could be differences..

Mars

I've considered a post-boil to lower infection odds, but seems like a chunk of time and energy to get up there and back down again. Besides, if I never get hot enough to denature, then theoretically, I'll be converting still after pitching.

[Ben]

The only real problem with no boil no chill is if you get a grain that carries clostridium, then you get butyric. Post conversion can be aided with powdered amylase or sebamyl GL if you choose to boil. If you are mashing in the 145°f range and complete starch conversion there shouldn't be much left.

Immersion chilling isn't the only option, counterflow chillers are fast and effective, and can be really inexpensive to build if you have leftover copper coil.

[BlueSasquatch]

The only real problem with no boil no chill is if you get a grain that carries clostridium, then you get butyric. Post conversion can be aided with powdered amylase or sebamyl GL if you choose to boil. If you are mashing in the 145°f range and complete starch conversion there shouldn't be much left.

Immersion chilling isn't the only option, counterflow chillers are fast and effective, and can be really inexpensive to build if you have leftover copper coil.

Right, I get butyric often enough, I figured it could be small scratches in the plastic HDPE fermenting buckets/barrels, another reason I'm switching to kegs to ferment in.

With any of the chillers; Immersion, Plate, Counterflow. You have exposure to your wort and thus require sanitation. Not a huge deal, but working towards less equipment, more things to sanitize, to clean, to store, etc. Now I know if one boils, it sanitizes the immersion coils, so it's not out of the question, just looking to avoid it, if I can. This isn't very cost prohibitive, and I don't think it would transfer heat very well, but had an idea at one point for a cooling jacket, that could also help maintain a mash temp



Saw facebook today selling 50 feet of 1" copper coil, damn $350, but didn't know they even made the coil in that large of diameter.

Anyways my current method of bringing the wort to pitch temp quickly is to mash with 50% water and then add the remaining 50% after conversion. Also enjoy mashing during winter because of this, just setting it outside.

[Ben]

Seems like you would be better off just using a vessel that is one size larger and putting a port in bottom and top, flood with water from the bottom up. You would need to agitate constantly for either to work.

Either one seems like a lot more work and energy than boiling with the immersion chiller. Could be integrated to the keg, then its just part of the keg and not another thing . Other advantage to an integrated immersion chiller is it can double as a HERMS coil.

[BlueSasquatch]

Seems like you would be better off just using a vessel that is one size larger and putting a port in bottom and top, flood with water from the bottom up. You would need to agitate constantly for either to work.

Either one seems like a lot more work and energy than boiling with the immersion chiller. Could be integrated to the keg, then its just part of the keg and not another thing . Other advantage to an integrated immersion chiller is it can double as a HERMS coil.

Right, thousands of people I reckon homebrewers, mash and use these tools, so not much sense in me throwing a tantrum over them, yet I am.

On the long to-do list is a glycol chiller DIY which would require me to embrace one of those immersions or counter-flow, etc. I figure I'll end up with immersion since I'm wanting to ferment and distill On-grain. Which also poses an issue with a post-boil.

But who knows, after my stripper is up and running, maybe I'll not notice a difference between on-off grain, in which case I'd likely pursue a post-boil + immersion glycol chiller.

[Steve Broady]

I just tested the batch that I have fermenting. As near as I can tell using pH test strips, it’s around 5. I’m not experienced enough to get more accurate than that. On the theory that acidity is causing profit me, I added another gallon of warm water and a small handful of oyster shells. Hopefully it doesn’t hurt, at least.

[StillerBoy]

I just tested the batch that I have fermenting. As near as I can tell using pH test strips, it’s around 5. I’m not experienced enough to get more accurate than that. On the theory that acidity is causing profit me, I added another gallon of warm water and a small handful of oyster shells. Hopefully it doesn’t hurt, at least.

Why was extra water and oyster shells with Ph of 5... what was the reasoning behind that action..

Mars

[howie]

I used to be a big fan of Iodine test but have shifted more into running a Home-Brewer's Calculator on the content of the mash, to give me a target SG to hit, and then take readings during the mashing process to get a better gauge of where I am at. After a long rest at temp, things have settled enough that you can do a light stir of the middle liquid, without disturbing the solids, and then pull a sample jar. The home-brewers calcs also tend to push that 75% conversion is good, and shooting for "100% conversion" is a losing battle.

For mashing, look no further than beer gurus, they have it down. (Ignore their bit about a post-boil)


Poor conversion for my all-grains always comes back to: Not enough rest time at temp. - Better insulation and left alone for longer.

i still do iodine test sometimes but obv that only tells you that you have converted the starches you have managed to extract from the grain.
it doesn't tell you if you've left a shitload of starch behind by poor conversion.
the other day i saw a post saying they had 10kg of grain and only got an OG of 1.030 and quote 'the iodine test was ok"
so until someone invents a starchometer, i will rely on beer apps, calculators and hydrometers ( and hopefully good mashing processes) to get a reasonable idea of my expected OG/FG/abv etc.