Quantcast

How Important is length of Mash?

HomeBrewTalk.com - Beer, Wine, Mead, & Cider Brewing Discussion Community.

Help Support Homebrew Talk:

Schumed

Well-Known Member
Joined
Feb 26, 2011
Messages
1,112
Reaction score
92
Location
Kansas City
Been wondering and haven't found a whole lot of good research but how much time is really need for conversion for a typical Mash....my Mash tun recently has really been dramatically dropping temps after 30 minutes going from 150 to 140 very quickly...but haven't notice any change in efficiency and final product has been great

What I want to know is there research on how much time you really need to convert at optimal temps?
 
OP
Schumed

Schumed

Well-Known Member
Joined
Feb 26, 2011
Messages
1,112
Reaction score
92
Location
Kansas City
I use an insulated keggle with a false bottom for reference
 

RM-MN

Supporting Member
HBT Supporter
Joined
Nov 26, 2010
Messages
14,369
Reaction score
5,094
Location
Solway
You can use iodine to tell if you have any starch left. Just collect a sample (a drop or 2) of your wort, put it on something like a white plate so you can see color changes and add a drop of iodine next to it. Use a toothpick to mix the two. If it turns blue, there is still starch. If the iodine stays reddish, there is no starch left.

Your enzymes work over a range of temperatures so you get conversion from alpha amylase and beta amylase as it cools. Starting at 150 would get you a pretty dry beer and as the temperature goes down, the beta amylase has more effect and will make the wort more fermentable. If you start at a higher temperature the wort will be less fermentable because beta amylase is denatured at the higher temperatures. Your efficiency won't change but the fermentability of the wort will.

I'd read that the enzymes work quickly but I couldn't find a definitive number of minutes or hours so I experimented by starting a batch with the intent of taking an immediate sample and then one every 5 minutes until I got no change in color with my iodine. I BIAB so my grains were ground fine. At mash in the sample turned dark blue, so there definitely was starch. I missed the 5 minute mark and grabbed the sample at 7 minutes. No change in color, so the enzymes reacted in less than 7 minutes.

With a coarser crush, you need to get the water to the center of the particles to get the conversion since the dry grain won't convert. That's where the 60 minute mash becomes necessary as you wait for the grains to get wet and leach the sugars back out.
 
Joined
Apr 18, 2010
Messages
293
Reaction score
5
Location
Houston
I have heard people mention conversion times of as low as 15 to 20 minutes, but I always go with 60 just to be safe. At lower temps (e.g. 148-149) it can take longer.
 
OP
Schumed

Schumed

Well-Known Member
Joined
Feb 26, 2011
Messages
1,112
Reaction score
92
Location
Kansas City
RM-MN said:
You can use iodine to tell if you have any starch left. Just collect a sample (a drop or 2) of your wort, put it on something like a white plate so you can see color changes and add a drop of iodine next to it. Use a toothpick to mix the two. If it turns blue, there is still starch. If the iodine stays reddish, there is no starch left.

Your enzymes work over a range of temperatures so you get conversion from alpha amylase and beta amylase as it cools. Starting at 150 would get you a pretty dry beer and as the temperature goes down, the beta amylase has more effect and will make the wort more fermentable. If you start at a higher temperature the wort will be less fermentable because beta amylase is denatured at the higher temperatures. Your efficiency won't change but the fermentability of the wort will.

I'd read that the enzymes work quickly but I couldn't find a definitive number of minutes or hours so I experimented by starting a batch with the intent of taking an immediate sample and then one every 5 minutes until I got no change in color with my iodine. I BIAB so my grains were ground fine. At mash in the sample turned dark blue, so there definitely was starch. I missed the 5 minute mark and grabbed the sample at 7 minutes. No change in color, so the enzymes reacted in less than 7 minutes.

With a coarser crush, you need to get the water to the center of the particles to get the conversion since the dry grain won't convert. That's where the 60 minute mash becomes necessary as you wait for the grains to get wet and leach the sugars back out.
I'll have to try the iodine test and do some experimenting thanks for the info
 

wobdee

Junior Member
Joined
Dec 1, 2012
Messages
1,064
Reaction score
100
Location
Lake Wissota
I do BIAB and go 45 minutes for mash then turn up the heat for mash out. With my fine crush I think I could probably cut that time down to 30 min or less if I checked with iodine but I wonder how accurate the iodine test really is?
 
OP
Schumed

Schumed

Well-Known Member
Joined
Feb 26, 2011
Messages
1,112
Reaction score
92
Location
Kansas City
bumstigedy said:
I have heard people mention conversion times of as low as 15 to 20 minutes, but I always go with 60 just to be safe. At lower temps (e.g. 148-149) it can take longer.
That its kind of what I've seen in my research but no real numbers to back that up though....my theory is 20 minutes is enough time but ill have to test and report back...going to see if anyone in my brew club wants to try to test too to get a larger sample
 

nicklepickles

Well-Known Member
Joined
Mar 2, 2012
Messages
235
Reaction score
29
Havent tried iodine tests, but ive heard they only check for if conversion has started yet, but not the extent of how much conversion has actually taken place. So you potentially have an iodine test say conversion has started, but you could still have some unconverted starches in there. Any truth to this?
 

billl

Well-Known Member
Joined
May 25, 2012
Messages
2,381
Reaction score
421
Location
Raleigh
Iodine is testing for starch in suspension. It's doesn't tell you if you got all the starch out of the grains in the first place.
 

ajf

Senior Member
Lifetime Supporter
Joined
Oct 29, 2005
Messages
4,648
Reaction score
119
Location
Long Island
I have read that mashing at lower temperatures takes longer for conversion (Dave Miller). I've also read that poorly crushed grain takes longer to convert (on this forum). I have also read that the color change with iodine indicate the degree of conversion (Greg Noonan).
I cannot quantify these statements, but when I started mashing at 150F, I did do an iodine test at 60 minutes and 90 minutes. The 60 minute sample turned blue (indicating starch), but the 90 minute test turned yellow (with a faint reddish tint) indicating complete conversion. I cannot even guarantee that the 60 minute test was accurate. There may have been some husk material in the wort sample which could give a false reading.
For me however, this is all academic as it takes me 90 minutes to heat my sparge water for most brews, so I have to sparge for 90 minutes, which works well for me.

-a.
 

reinstone

Well-Known Member
Joined
Sep 1, 2011
Messages
1,242
Reaction score
118
A starch test shows positive for starch or not positive. It does not show how.....far the starch is broken down.....it is an indicator that conversion is complete.....not that the sugar profile is where you want it to be, depending. Remember John palmers mashing allegory...maybe only one process has taken place......if I'm correct sugars are further degraded by specific enzymes from longer chain sugars, temp and time affect on how far they are degraded. Thus a longer mash...,further degradation and better attenuation....more simple sugars. So yes conversion can be complete......but the degree of the sugar profile in the wort is dependent beyond that.


Remember enzymes are active over an overlapping range......so you time will be more dependent on temps....and your wort profile will be dependent as well......but more so at lower temps.
 
Joined
Apr 23, 2009
Messages
34,111
Reaction score
13,124
Location
☀️ Clearwater, FL ☀️
I have read that mashing at lower temperatures takes longer for conversion (Dave Miller). I've also read that poorly crushed grain takes longer to convert (on this forum). I have also read that the color change with iodine indicate the degree of conversion (Greg Noonan).
I cannot quantify these statements, but when I started mashing at 150F, I did do an iodine test at 60 minutes and 90 minutes. The 60 minute sample turned blue (indicating starch), but the 90 minute test turned yellow (with a faint reddish tint) indicating complete conversion. I cannot even guarantee that the 60 minute test was accurate. There may have been some husk material in the wort sample which could give a false reading.
For me however, this is all academic as it takes me 90 minutes to heat my sparge water for most brews, so I have to sparge for 90 minutes, which works well for me.

-a.
Regarding the crush, I read a very compelling report with pictures by Breiss that indicated the crush is not important AT ALL with respect to extraction of sugars. In fact, they recorded fair extraction without crushing at all. This is the opposite of what is stated here repeatedly. See this post and the related links: https://www.homebrewtalk.com/f36/any-real-science-effect-crush-extract-yield-326573/#post4061244

I bought iodine when I first started brewing. It would register conversion in about 20 minutes. I haven't used it in years since it always converted.
 

RM-MN

Supporting Member
HBT Supporter
Joined
Nov 26, 2010
Messages
14,369
Reaction score
5,094
Location
Solway
Kai Troester has the answers. That guy is great. For those averse to reading the data, 2 additional hours of mash time will earn you about 4% more attenuation in the beer.

http://braukaiser.com/wiki/index.php?title=Mash_Time_Dependency_of_Wort_Fermentability
An interesting read but I'm not convinced that his conclusions are valid for BIAB. His sample tested negative for starch at 40 minutes. Mine tested negative at 7 minutes. Quite a difference.

He does show a gain of fermentability with more time but such a small gain for the extra time that I'd wonder if nearly all of the conversion including the breakdown of the longer chain sugars happened much earlier than the 2 hours and just a difference in the yeast gave those results.

The software I've been using assumes a 75% attenuation with a 60 minute mash. I've been doing a 30 minute mash and getting higher attenuation than that, probably nearer to 80 to 85% attenuation. Shouldn't I be getting less attenuation with that short mash?
 
Joined
Apr 23, 2009
Messages
34,111
Reaction score
13,124
Location
☀️ Clearwater, FL ☀️
An interesting read but I'm not convinced that his conclusions are valid for BIAB. His sample tested negative for starch at 40 minutes. Mine tested negative at 7 minutes. Quite a difference.

He does show a gain of fermentability with more time but such a small gain for the extra time that I'd wonder if nearly all of the conversion including the breakdown of the longer chain sugars happened much earlier than the 2 hours and just a difference in the yeast gave those results.

The software I've been using assumes a 75% attenuation with a 60 minute mash. I've been doing a 30 minute mash and getting higher attenuation than that, probably nearer to 80 to 85% attenuation. Shouldn't I be getting less attenuation with that short mash?
I've got no answers. Honestly, I don't care, either. I use a refractometer to make sure my OG into the ferementor is exactly what I want. But of course I don't want to pass on bad info, so I do appreciate you posting your experience here.
 

neosapien

Well-Known Member
Joined
Mar 18, 2012
Messages
709
Reaction score
143
Location
Dallas
There's a thread buried on here somewhere with experiments showing conversion in around (as little as) 10 minutes. I'm not sure if Kai's method actually included tests for <40 minutes or not based on his wording. All in all, it seems like a fairly conclusive scientific method he used. How do you think BIAB conclusions would be different?
 

RM-MN

Supporting Member
HBT Supporter
Joined
Nov 26, 2010
Messages
14,369
Reaction score
5,094
Location
Solway
Regarding the crush, I read a very compelling report with pictures by Breiss that indicated the crush is not important AT ALL with respect to extraction of sugars. In fact, they recorded fair extraction without crushing at all. This is the opposite of what is stated here repeatedly.

I bought iodine when I first started brewing. It would register conversion in about 20 minutes. I haven't used it in years since it always converted.
I wonder about the report that crush is not important as when people have poor efficiency, we tell them to crush better and their efficiency goes up. Why such differences in the results? Why is the definitive extract potential measured in a congress mash where the grains are ground to flour instead of left whole? Things are not adding up.

Some day I may have to try that, mashing some uncrushed grain and then cutting open a kernel after the end of the mash to see if it got wet to the center, if it has any starch left in that kernel, and if the kernel is sweet, indicating that the sugars were not extracted.

I may have to try the iodine test again too just to see how quickly the conversion occurs. Since my test said I had conversion in 7 minutes, where do I have partial conversion.
 

RM-MN

Supporting Member
HBT Supporter
Joined
Nov 26, 2010
Messages
14,369
Reaction score
5,094
Location
Solway
There's a thread buried on here somewhere with experiments showing conversion in around (as little as) 10 minutes. I'm not sure if Kai's method actually included tests for <40 minutes or not based on his wording. All in all, it seems like a fairly conclusive scientific method he used. How do you think BIAB conclusions would be different?
To get conversion from starch to malt sugar you need to get the grain particles wet to the center. Any part of the kernel that doesn't get wet doesn't convert but you don't extract either starch or sugar from it either. With my BIAB, I grind the grains quite fine. I'm pretty sure that helps the particles wet. My measured efficiency says so too. Maybe more of us need to experiment with this and use different crush/grind to see how it changes.
 
Joined
Apr 23, 2009
Messages
34,111
Reaction score
13,124
Location
☀️ Clearwater, FL ☀️

RM-MN

Supporting Member
HBT Supporter
Joined
Nov 26, 2010
Messages
14,369
Reaction score
5,094
Location
Solway
https://www.homebrewtalk.com/f36/any-real-science-effect-crush-extract-yield-326573/#post4061244

I edited and added the link above, but here you go anyway. It's a little hard to understand what the numbers in the table mean, but the point is that they got great efficiency from everything that that was crushed at all.
Nice table. So without crushing at all they got 24% efficiency. Not too unexpected as soaking the grains will wet them eventually and you can leach the sugars out some. The question I have is the length of time that it takes to get 94% efficiency with the coarse milling. That doesn't seem to be available info. Do they do a 30 minute mash, 60 minute, 90 minute, or are they talking 24 hours? I don't want to wait for a long mash, I expect to get my beer brewed and get on to other jobs. I seem to get great efficiency with a fine grind and a 30 minute mash and I get very good attenuation which makes me think I got the right mix of long and short chain sugars too as if all I got were long chain my attenuation would suffer. Lots of questions, hard to find solid answers to many of them.
 

billl

Well-Known Member
Joined
May 25, 2012
Messages
2,381
Reaction score
421
Location
Raleigh
Just a note on that experiment.

Their categories for what is fine vs coarse are using pans of 0.60mm and 0.25mm. That is a much wider range than anyone is setting their grain mills. Unless they are milling with a huge gap, everything in that 0.60mm bin should be husks plus whatever grain happens to get stuck to them. If you mill setting is less than 0.60mm, pretty much everything else should be falling through a 0.60mm screen.
 

ajf

Senior Member
Lifetime Supporter
Joined
Oct 29, 2005
Messages
4,648
Reaction score
119
Location
Long Island
A starch test shows positive for starch or not positive. It does not show how.....far the starch is broken down.....it is an indicator that conversion is complete.....not that the sugar profile is where you want it to be, depending.
But according to Noonan the color of the sample does indicate the sugar profile. I'm not saying he is right, and I'm not saying he is wrong; but that is what he wrote in New Brewing Lager Beer.

-a.
 

globe

Well-Known Member
Joined
Oct 22, 2012
Messages
130
Reaction score
10
Location
Madison
I thought i was losing 10 degrees over an hour until i took temp reading after mixing the mash. My thermometer is on the bottome of my kettle. If yours is the same way the temp can vary a lot. Mix then see, its hard to lose a ton of heat.
 

reinstone

Well-Known Member
Joined
Sep 1, 2011
Messages
1,242
Reaction score
118
But according to Noonan the color of the sample does indicate the sugar profile. I'm not saying he is right, and I'm not saying he is wrong; but that is what he wrote in New Brewing Lager Beer.

-a.
Ah, I think it was bamforth stating this. That starch test does not show how far sugar is degraded. .....maybe.. not sure.
 
Joined
Jun 7, 2011
Messages
4,858
Reaction score
1,473
Location
The Frozen Tundra
Regarding the crush, I read a very compelling report with pictures by Breiss that indicated the crush is not important AT ALL with respect to extraction of sugars. In fact, they recorded fair extraction without crushing at all. This is the opposite of what is stated here repeatedly. See this post and the related links: https://www.homebrewtalk.com/f36/any-real-science-effect-crush-extract-yield-326573/#post4061244

I bought iodine when I first started brewing. It would register conversion in about 20 minutes. I haven't used it in years since it always converted.
I had this happen a few years back.

When I first started doing all grain I used to order my grains crushed because I didn't have a mill. I was pretty new and I got an order where the base malt was completely uncrushed. I was clueless and went ahead and mashed it. I didn't notice until I was done with the mash. My OG was lower than expeceted, but the beer still came out fine.
 
Top