70 replies to this topic

[Genesee Ted]

I am interested in hearing some ideas about when a mash is "done" so to speak. There is the camp that says to mash until the iodine test says you are fully converted and then proceed. Seems to make some sense. We are trying to make sugars from starches, and once they are done, run it. Contrary to this, much of the brewing literature I consume emphasize mashing for 45 minutes, an hour, or sometimes even more. What do you all think from your experiences and research? Is there any benefit (measurable and/or perceivable) to keeping with the traditional longer mash times? I suspect that this set of questions treads dangerously close to the classic decoction debates, but I do think that they are important issues on the hot side

[MtnBrewer]

The mash is done when you've reached the dextrin profile that you want for the beer you're trying to make. So if you're trying to make a really dry beer, passing an iodine test might not be enough. People tend to oversimplify the mash as a binary process when it's really a continuum. In other words, people think in terms of done or not done instead of how done is it? Also, most reactions go faster at higher temperatures so a cooler mash will likely take longer than a higher temperature one.

[SchwanzBrewer]

The mash is done when you've reached the dextrin profile that you want for the beer you're trying to make. So if you're trying to make a really dry beer, passing an iodine test might not be enough. People tend to oversimplify the mash as a binary process when it's really a continuum. In other words, people think in terms of done or not done instead of how done is it? Also, most reactions go faster at higher temperatures so a cooler mash will likely take longer than a higher temperature one.

This. Passing the iodine test does not mean the mash is done. That just means the starches have been converted to long chain dextrins. Those dextrins still need breaking down into maltose and maltotriose and like mtn said, only time and right temp can do that. The best we have is to make the beer and find the OG/FG, go back to our notes, and try to figure out how our system works for the variables we can control.

[Genesee Ted]

Pretty much how I have always looked at it. I just keep getting noise from the fringes about not worrying about it and it got me to wondering about whether or not this was just superstition.

[Brauer]

An iodine test isn't very valuable for determining if a mash has actually completely converted. I find that a much more useful number is the expected gravity at 100% conversion, for you grist weight and mash volume.

[denny]

An iodine test isn't very valuable for determining if a mash has actually completely converted. I find that a much more useful number is the expected gravity at 100% conversion, for you grist weight and mash volume.

Yep. I use Kai's conversion efficiency chart.

[Clintama]

Mash overnight and you'll never have to worry.

[davelew]

There was a lot of talk 5 to 10 years ago about kurz-hoch mashing methods, which only mash for 15 minutes. I'd say that mash length is just one of the many variables that can be used to alter a beer, there are commercial beers brewed with anywhere from a 15 minute (Drayman's) to a many hour (some Belgians) long mash

[denny]

Mash overnight and you'll never have to worry.

Maybe so, but that almost never works with my schedule.

[denny]

There was a lot of talk 5 to 10 years ago about kurz-hoch mashing methods, which only mash for 15 minutes. I'd say that mash length is just one of the many variables that can be used to alter a beer, there are commercial beers brewed with anywhere from a 15 minute (Drayman's) to a many hour (some Belgians) long mash

One thing that seems to be often overlooked when talking about commercial brewers short mash times are the mash in and lauter times. They might only hold a rest for 15 min., but between mash in and lautering they're at mash temps for a much longer time. Hours usually.

[SchwanzBrewer]

One thing that seems to be often overlooked when talking about commercial brewers short mash times are the mash in and lauter times. They might only hold a rest for 15 min., but between mash in and lautering they're at mash temps for a much longer time. Hours usually.

This.

[MtnBrewer]

Mash overnight and you'll never have to worry.

I don't worry now.

[Clintama]

I don't worry now.

Neither do I.

[Genesee Ted]

One thing that seems to be often overlooked when talking about commercial brewers short mash times are the mash in and lauter times. They might only hold a rest for 15 min., but between mash in and lautering they're at mash temps for a much longer time. Hours usually.

I have thought of this of course, but even when I read published recipes and techniques to brew them, it still seems like I see a 45 to 60 min saccharification rest. Is it that they start timing the rests differently?

[Brauer]

There was a lot of talk 5 to 10 years ago about kurz-hoch mashing methods, which only mash for 15 minutes. I'd say that mash length is just one of the many variables that can be used to alter a beer, there are commercial beers brewed with anywhere from a 15 minute (Drayman's) to a many hour (some Belgians) long mash

I typically use a Hochkurz mash. What I think the 'short' usually refers to is the short beta amylase rest. A common schedule is a 30-40 minute beta rest followed by a 20-30 minute alpha amylase rest at a higher temperature (hoch). I think that a 1 hour total mash is still considered short (kurz) by German breweries.

[djinkc]

I don't worry now.

Neither do I.

If tempted to worry I have a beer........

An iodine test isn't very valuable for determining if a mash has actually completely converted. I find that a much more useful number is the expected gravity at 100% conversion, for you grist weight and mash volume.

What am I missing? Iodine says there is no starch, or not much anyway. Does gravity change when longer sugars break down to shorter chains? I would think a dextrinous wort and all maltose wort would have the same or very close gravities. I agree you may not have the profile you want when the starch is converted but once you have dissolved sugars I don't see why the gravity would change.

Edited by djinkc, 20 February 2013 - 05:43 PM.

[Genesee Ted]

What am I missing? Iodine says there is no starch, or not much anyway. Does gravity change when longer sugars break down to shorter chains? I would think a dextinous wort and all maltose wort would have the same or very close gravities. I agree you may not have the profile you want when the starch is converted but once you have dissolved sugars I don't see why the gravity would change.

I am with you here. If conversion is done, gravity won't change, but perhaps the makeup of the carbohydrates will be. I guess what my question is getting at is do you lose a certain amount of control over the composition of your wort by mashing shorter or are we just using unicorn tears?

[Brauer]

What am I missing? Iodine says there is no starch, or not much anyway.

Iodine only tells you that the starch that has been solubilized has been converted. Early in the mash, enzyme is limiting and you'll get a positive starch test. 20-30 minutes in you'll often have converted enough of the starch that was in solution, that starch gelatinization becomes limiting. At that point you can get a negative iodine test but have a significant percentage of ungelatinized starch. Gravity will tell you when you are approaching the point where you have turned 100% of the starch into sugars.

[djinkc]

Iodine only tells you that the starch that has been solubilized has been converted.Early in the mash, enzyme is limiting and you'll get a positive starch test. 20-30 minutes in you'll often have converted enough of the starch that was in solution, that starch gelatinization becomes limiting. At that point you can get a negative iodine test but have a significant percentage of ungelatinized starch. Gravity will tell you when you are approaching the point where you have turned 100% of the starch into sugars.

Makes perfect sense - thanks. Actually, someone has told me this before (and I forgot). I would guess the finer the crush the less this would be a factor.

[Genesee Ted]

Iodine only tells you that the starch that has been solubilized has been converted.Early in the mash, enzyme is limiting and you'll get a positive starch test. 20-30 minutes in you'll often have converted enough of the starch that was in solution, that starch gelatinization becomes limiting. At that point you can get a negative iodine test but have a significant percentage of ungelatinized starch. Gravity will tell you when you are approaching the point where you have turned 100% of the starch into sugars.

How do you know what your gravity should be if you don't know the efficiency of the system? Is it just a calculation based on theoretical values? Serious questions, no snark at all...