Author Topic: When is the Mash Complete?  (Read 2929 times)

KellerBrauer

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When is the Mash Complete?
« on: December 22, 2017, 08:24:05 AM »
Greetings All - I have read many articles on this subject, and the more I read the more confused I get.  The simple question is:  How do you know when a mash is complete and all the starches have been converted?  Some recipes call for a 60 minute mash while others call for a 70, 80 or even a 90 minute mash.  I have read that many brewers use iodine as a test method. So how do you know when it?s complete and how does iodine help determine this?  Am I trying to over think this or should I just go with the flow?

Offline GigaFemto

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Re: When is the Mash Complete?
« Reply #1 on: December 22, 2017, 10:29:33 AM »
It depends on your definition of complete. The iodine test will tell you when all the starches have been converted to sugars, but it doesn't tell you which sugars. My understanding is that although the starch test might indicate "completion" within 20 minutes, continuing the mash will allow various processes to continue, including breaking down of larger sugars into smaller ones, delivering a different wort and higher fermentability. If you have highly modified malt and are in a hurry you can probably get by with a 20-30 minute mash, but you will not get the same beer that you will if you mash for longer. I no longer use the iodine test and just mash for an hour in all cases.

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Offline Kevin58

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Re: When is the Mash Complete?
« Reply #2 on: December 22, 2017, 11:10:59 AM »
Use a white plate or dish. Put some of your wort on the dish.... try to avoid grain bits, you only want the liquid. Put a drop of iodine on the wort and if starches are present the color will be black. As the starch is converted to sugar the color will become a golden brown or amber color.
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KellerBrauer

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Re: When is the Mash Complete?
« Reply #3 on: December 22, 2017, 01:05:08 PM »
Greetings Kevin & Giga - very interesting information, thank you for your response.  So, if I understand, I?m covered with a 60 minute mash and if I choose to use iodine, the iodine tells me if all the starches are converted.  So, theoretically, after a 60 minute mash, the iodine will turn brown/amber if all the starches are converted.  If the iodine is still black, I should leave the mash longer?

I have been accustomed to doing a 60 minute mash (possibly a bit longer if my strike water isn?t ready) and I?m trying to figure out if I?m actually converting as much starch as possible in an attempt to possibly increase my efficiency.

Great answers!  Thanks for your help!!!

Offline Ck27

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Re: When is the Mash Complete?
« Reply #4 on: December 22, 2017, 01:15:08 PM »
Greetings Kevin & Giga - very interesting information, thank you for your response.  So, if I understand, I?m covered with a 60 minute mash and if I choose to use iodine, the iodine tells me if all the starches are converted.  So, theoretically, after a 60 minute mash, the iodine will turn brown/amber if all the starches are converted.  If the iodine is still black, I should leave the mash longer?

I have been accustomed to doing a 60 minute mash (possibly a bit longer if my strike water isn?t ready) and I?m trying to figure out if I?m actually converting as much starch as possible in an attempt to possibly increase my efficiency.

Great answers!  Thanks for your help!!!

Length of mash counts, but so does crush and temperature of the water.

What temperature are you targeting usually? How fine is your grain crush?

Offline GigaFemto

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Re: When is the Mash Complete?
« Reply #5 on: December 22, 2017, 02:43:17 PM »
I think an hour should cover it in terms of conversion of starches in essentially all cases. You can do an iodine test if you want. It is cheap and easy, and will give you something to do while you wait.

Some malts that have fewer enzymes in them (i.e. lower diastatic power) may benefit from longer mashes. For example, Great Western Premium 2-row has a diastatic power of 140 Lintner, and will probably convert pretty fast, while Munich only has a distatic power of 40 Lintner. If you use all Munich, plus kilned or roasted malts that have no enzymes, it will take longer for the reduced enzyme concentration to fully convert the mash. A recent article in BYO magazine (https://byo.com/article/brewing-by-ratio/ ) says that the average diastatic power of your gran bill (weighted average of individual malts in the mix)  should not be lower than 40, so a mash like the one I just described should be avoided. Adding a bit of high diastatic power 2-row would be helpful.

Temperature also makes a difference, but not in a simple way. Chemical reactions go faster at higher temperatures, so conversion happens faster, but the enzymes also get denatured faster so their lifetime is shorter at high temperatures. If you have plenty of enzymes, then the shorter lifetime is not a problem, but if  you are low on diastatic power in the first place you may find that a higher temperature does not give you faster conversion.

The bottom line for me is that patience is a virtue and I shouldn't try to rush the mashing process. I always calculate the diastatic power of my grain bill and try to keep it high enough that an hour mash should be plenty of time.

--GF

KellerBrauer

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Re: When is the Mash Complete?
« Reply #6 on: December 23, 2017, 05:33:18 AM »
I think an hour should cover it in terms of conversion of starches in essentially all cases. You can do an iodine test if you want. It is cheap and easy, and will give you something to do while you wait.

Some malts that have fewer enzymes in them (i.e. lower diastatic power) may benefit from longer mashes. For example, Great Western Premium 2-row has a diastatic power of 140 Lintner, and will probably convert pretty fast, while Munich only has a distatic power of 40 Lintner. If you use all Munich, plus kilned or roasted malts that have no enzymes, it will take longer for the reduced enzyme concentration to fully convert the mash. A recent article in BYO magazine (https://byo.com/article/brewing-by-ratio/ ) says that the average diastatic power of your gran bill (weighted average of individual malts in the mix)  should not be lower than 40, so a mash like the one I just described should be avoided. Adding a bit of high diastatic power 2-row would be helpful.

Temperature also makes a difference, but not in a simple way. Chemical reactions go faster at higher temperatures, so conversion happens faster, but the enzymes also get denatured faster so their lifetime is shorter at high temperatures. If you have plenty of enzymes, then the shorter lifetime is not a problem, but if  you are low on diastatic power in the first place you may find that a higher temperature does not give you faster conversion.

The bottom line for me is that patience is a virtue and I shouldn't try to rush the mashing process. I always calculate the diastatic power of my grain bill and try to keep it high enough that an hour mash should be plenty of time.

--GF

Greetings GigaFemto - you must have been reading my mind.  I got to thinking about the information you and Kevin presented yesterday and began wondering why some recipes call for a 70, 80 and sometimes 90 minute mash.  Now I understand why.  And yes, I read the article in BYO about brewing by ratio and that article also added, or contributed to, my confusion.

So, with your detailed and comprehensive answer in mind, would it make sense that the BS2 software did some basic calculations and at least warned or alerted a brewer that the grain bill did not have enough diastatic power to properly convert all the starches; or maybe offer a recommended mash duration?  Or, perhaps it does and I?m not looking at it??
« Last Edit: December 23, 2017, 05:35:50 AM by KellerBrauer »

Online Oginme

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Re: When is the Mash Complete?
« Reply #7 on: December 23, 2017, 06:26:25 AM »

So, with your detailed and comprehensive answer in mind, would it make sense that the BS2 software did some basic calculations and at least warned or alerted a brewer that the grain bill did not have enough diastatic power to properly convert all the starches; or maybe offer a recommended mash duration?  Or, perhaps it does and I?m not looking at it??

KellerBrauer, 

Certainly, the information is available within BeerSmith to calculate for low diastatic power to convert a mash efficiently and throw up an alert.  I think this would be a great addition to the program.


OTOH, so much of the rate of conversion relies on the mash temperature and water to grist ratio (in addition to process variables of grist addition, stirring before and during mash, grind quality of the grist) that I think it might be problematic to "recommend" a mash time based upon a calculation. 

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KellerBrauer

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Re: When is the Mash Complete?
« Reply #8 on: December 23, 2017, 10:30:34 AM »

OTOH, so much of the rate of conversion relies on the mash temperature and water to grist ratio (in addition to process variables of grist addition, stirring before and during mash, grind quality of the grist) that I think it might be problematic to "recommend" a mash time based upon a calculation.

Greetings Oginme - your response makes perfect sense, and thank you.  However, I think all of the information needed to send off a warning (blue, yellow or red balls such as we see now) if the diastatic power of a grain bill is too low.  All that would be needed is a person smarter than myself to figure out the formula.  You?re right, recommending a mash time could be opening pandoras proverbial box.

Thanks for your help!!

Offline brewfun

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Re: When is the Mash Complete?
« Reply #9 on: December 23, 2017, 11:35:09 AM »
It depends on your definition of complete. The iodine test will tell you when all the starches have been converted to sugars, but it doesn't tell you which sugars.

This! Yes!

Quote
My understanding is that although the starch test might indicate "completion" within 20 minutes, continuing the mash will allow various processes to continue, including breaking down of larger sugars into smaller ones, delivering a different wort and higher fermentability.

Exactly. This needs to be reinforced, IMO. The iodine test actually tells you if debranching has finished, breaking long chain starches into various forms of shorter starches and sugars that don't react to iodine.

I prefer to watch the first wort gravity. If it's still rising, then the mash isn't complete, in my book. I can get a clean iodine result when the first wort is only 10 P (about 1.040). I'm looking for 20 to 26 P (about 1.080 to 1.115) before I sparge. You get about half your wort sugar from the first runnings (about 1/3 of your kettle volume) and the other half from the next 2/3. I find that waiting for the first wort gravity to stop rising has a positive effect on overall efficiency.
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Offline GigaFemto

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Re: When is the Mash Complete?
« Reply #10 on: December 23, 2017, 12:30:09 PM »

Greetings Oginme - your response makes perfect sense, and thank you.  However, I think all of the information needed to send off a warning (blue, yellow or red balls such as we see now) if the diastatic power of a grain bill is too low.  All that would be needed is a person smarter than myself to figure out the formula.  You?re right, recommending a mash time could be opening pandoras proverbial box.

Thanks for your help!!

The formula was given in the BYO article about brewing by ratio. Mathematically, it is the same as the SRM calculation, being the weighted average of the different grains but using the diastatic power in Lintner instead of the color in SRM. I have attached an Excel spreadsheet that does the calculation, in case that will help you.

--GF

KellerBrauer

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Re: When is the Mash Complete?
« Reply #11 on: December 23, 2017, 07:37:57 PM »
Greetings All - thank you all for the great information.  I Never expected to learn as much as I did from this post!  And thanks for the spreadsheet.  The calculation seems too easy.

 

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