Confused on Mash duration/ End point

[scogan]

I was reading someone’s recipe the other day where they were hitting their figures on a 30 min mash , which I think they arrived at using the iodine test .I have heard folk say that they sometimes see a further rise in sg during mashing even after the iodine test points to the end point .I am further confused because since we only typically get 75 % efficiency does that mean a lot of starch is never converted and if so, how do we manage to get a change on the iodine test ?

 

[tracer bullet]

I stopped using the iodine test, and use the iodine now for sanitization. I knew full well that if I had grains in hot water for a while it would simply show conversion. I can't imagine ever failing it.

I have seen a change to efficiency when mashing at 30, 60, and 90 minutes. Not a boat load but numbers something like high 60% at 30min, low 70% at an hour, and maybe 75% at an hour and a half. Those aren't exact numbers but are in the ballpark. I do see a change, but diminishing returns, and after about an hour and a half I doubt I'd get any more.

I'd be interested in what numbers others get.

 

[RM-MN]

Converting starch to sugars requires that first the starch is gelatinized. The larger the grain particles, the longer it takes to get the mash water to the starch to gelatinize. Once gelatinized the enzymes can convert. Then you need to get the sugars that are trapped in the grain particles back out into the wort.

When you start making the grain particles smaller you will eventually run into problems getting the wort out of the mash. If you make the grains particles too small they will plug up the filter.

To increase your efficiency (brewhouse?) you can mash longer so there is more time to gelatinize the starch, convert it, and extract the sugar. The problem with that is that unless you add heat, before all the conversion is done the mash has cooled so conversion stops. Adding heat has a tendency to denature the enzymes needed for conversion so you can lose that way too. Milling finer can help and adding something for a filter that doesn't plug so easily will help. People add rice hulls (cheap! add a handful) or...they use a different filter like a bag. That is where BIAB works well as you can mill the grains very fine and still not get a stuck mash as the bag has a huge filter area.

It may have been me that mentioned the 30 minute mash as I have used iodine to see if there is unconverted starch in the grain particles and I have used my refractometer to verify that the amount of sugar in the wort has quit going up.

If you have iodine, try an experiment with water and flour (not going to mill finer than that) Heat a small amount of water to 155F. and stir in a bit of flour. Remove a tiny bit of the flour and add a drop of iodine, starting at 5 minutes and continuing the experiment at 5 minute intervals until the iodine no longer changes color. Give a report back on what you find.

 

[scogan]

Converting starch to sugars requires that first the starch is gelatinized. The larger the grain particles, the longer it takes to get the mash water to the starch to gelatinize. Once gelatinized the enzymes can convert. Then you need to get the sugars that are trapped in the grain particles back out into the wort.

When you start making the grain particles smaller you will eventually run into problems getting the wort out of the mash. If you make the grains particles too small they will plug up the filter.

To increase your efficiency (brewhouse?) you can mash longer so there is more time to gelatinize the starch, convert it, and extract the sugar. The problem with that is that unless you add heat, before all the conversion is done the mash has cooled so conversion stops. Adding heat has a tendency to denature the enzymes needed for conversion so you can lose that way too. Milling finer can help and adding something for a filter that doesn't plug so easily will help. People add rice hulls (cheap! add a handful) or...they use a different filter like a bag. That is where BIAB works well as you can mill the grains very fine and still not get a stuck mash as the bag has a huge filter area.

It may have been me that mentioned the 30 minute mash as I have used iodine to see if there is unconverted starch in the grain particles and I have used my refractometer to verify that the amount of sugar in the wort has quit going up.

If you have iodine, try an experiment with water and flour (not going to mill finer than that) Heat a small amount of water to 155F. and stir in a bit of flour. Remove a tiny bit of the flour and add a drop of iodine, starting at 5 minutes and continuing the experiment at 5 minute intervals until the iodine no longer changes color. Give a report back on what you find.

Call me mean , but haven`t shelled out the $10 for iodine yet , as I suspect I will be persuaded to just continue 60 min mashes.
I suppose I could just take hydrometer readings till they are static.Can`t see the need to temperature adjust the reading at this stage (obviously assuming constant mash temp) as just looking for stasis.Here is a YT video of a guy doing that.

​

 

[Bassman2003]

Remember mashing is not just about creating sugar but also about shaping the interaction with yeast to create the beer you desire. Terms like fermentability come into play when you design a mash profile, time and temp play a part in how much fermentable sugars are created vs non-fermentable sugars. You can mash for 1 hour at 160F and get enough sugars to hit a gravity but that beer will have a fair amount of non-fermentable sugars. Mash for 3 hours at 160F and you will eventually break down to the level of getting more fermentable sugars and not wind up with a sugar bomb. Same goes in reverse with say 148F. Bud Light was/is reported to be mashed for five hours in the high 140's. They want to maximize the fermentability of the wort to the nth degree.

While we think of enzymes denaturing within time limits, it has been shown they are still there, just acting slower and slower.

Modern malts have had a lot of processing already baked in making a 30 minute mash possible. But I still would do at least a 60 minute mash or more depending on the style.

 

[DonT]

I use my refractometer to determine when the mash is complete. Depending on your mash thickness, where it ends up. This page has a good rundown on efficiency, in particular this chart. I typically use a 1.44 qt/lb mash thickness and at the end ~60min I'll be at 1.082 which is ~96% eff.
My usual process is the take my first reading at 30min and give it a good stir. Then I'll take a reading every 10min or so until it's done.

 

[hotbeer]

Iodine test only tells you if the starch rinsed out of the malts has converted into sugars. It's not going to tell you if you've separated as much of the potential sugar from the grains to have any particular Specific Gravity or not.

 

[doug293cz]

Call me mean , but haven`t shelled out the $10 for iodine yet , as I suspect I will be persuaded to just continue 60 min mashes.
I suppose I could just take hydrometer readings till they are static.Can`t see the need to temperature adjust the reading at this stage (obviously assuming constant mash temp) as just looking for stasis.Here is a YT video of a guy doing that.

​

Much easier to use a refractometer for this, rather than a hydrometer.

Brew on

 

[Bobby_M]

I mash until:
1. The gravity stops rising as measured every 10 minutes.
2. My calculated preboil gravity is reached (full volume mashing has an advantage that the mash gravity is the preboil so it's very easy to measure)
Whichever comes first.

 

[scogan]

I mash until:
1. The gravity stops rising as measured every 10 minutes.
2. My calculated preboil gravity is reached (full volume mashing has an advantage that the mash gravity is the preboil so it's very easy to measure)
Whichever comes first.

Are you using a refractometer ?
And do you find then that you often mash for less than an hour ?

 

[doug293cz]

2. My calculated preboil gravity is reached (full volume mashing has an advantage that the mash gravity is the preboil so it's very easy to measure)

Even if you don't do a full volume mash, the max possible mash wort SG can be calculated, and the mash terminated when that SG is reached (or terminated when the SG stops increasing.) Here is a table of max mash SG vs. mash thickness (in qt/lb) for a grain bill with a weighted average dry basis extract potential of 1.037 (80%) - which is pretty typical for most grain bills.

Brew on

 

[Bobby_M]

Are you using a refractometer ?
And do you find then that you often mash for less than an hour ?

To be precise, I use an Anton Paar Easydens, but a refractometer would work fine and is way more economical. The speed at which conversion happens is based on crush and mash temperature. Finer particals and higher mash temps are faster. Don't mistake that for a reason to raise mash temps because that's a whole other discussion, but if your mash temp is destined to be high then the conversion is usually faster than 60 minutes. On the contrary, a 148-150F mash might take 90-100 minutes.

 

[Bobby_M]

Even if you don't do a full volume mash, the max possible mash wort SG can be calculated, and the mash terminated when that SG is reached (or terminated when the SG stops increasing.) Here is a table of max mash SG vs. mash thickness (in qt/lb) for a grain bill with a weighted average dry basis extract potential of 1.037 (80%) - which is pretty typical for most grain bills.

View attachment 820401

Brew on

Right, I didn't mean to imply that full volume mashing was the only way. It's just often more convenient because brewing software tends to focus on preboil gravity targets. Brewfather has an experimental feature turned on now that shows the estimated mash gravity.

 

[scogan]

Even if you don't do a full volume mash, the max possible mash wort SG can be calculated, and the mash terminated when that SG is reached (or terminated when the SG stops increasing.) Here is a table of max mash SG vs. mash thickness (in qt/lb) for a grain bill with a weighted average dry basis extract potential of 1.037 (80%) - which is pretty typical for most grain bills.

View attachment 820401

Brew on

Do you include any oats in the mash thickness as I think they don`t contribute much fermentable sugar?

 

[day_trippr]

fwiw, oats, whether flaked or malted, can contribute virtually the same "points per gallon" as malted barley, typically running around 36-37 ppg...

http://beersmith.com/Grains/Grains/GrainList.htm

Cheers!