Benefits of letting mash rest for longer than required for conversion?

[Nathan Hassey]

I am trying to shorten my brew day and I hear a lot of people talking about starch conversion. The question I have is, what is the benefit of letting a mash rest for 60-90 min. If starch conversion is complete at 20 min, are there any reasons why I should let it go for a full 60 min? I read a lot about mashes being 60 min in books, articles, forums etc. Are they just assuming the worst case scenario and 60 min guarantees conversion without having to check? I have been mashing in a bag in a cooler to keep my temps for 60 min due to temp loss in the kettle. But if it truly only takes 20 min, I wouldn't have to worry about temps or dirtying up another vessel. Unless there was a benefit of letting it rest longer...Especially with BIAB and a fine grind, the conversion time could be very minimal. Thanks in advance!

Are there benefits to the fermentability of the wort with more time? The starch conversion has happend, but have the sugars broken down to the desired level for the desired body profile.

 

[Gnomebrewer]

A longer mash will generally give a more fermentable wort, as the beta amylase (slower acting) has time to work. Also, beware of these reports of 20 minute conversion - starch in solution converts very quickly, but getting the starch out of the grain takes longer. If these tests at 20 mins were only iodine tests of the liquid portion, they'll show conversion even though there is still starch in the grain. Most mashes are longer because the grains are crushed more coarsely than BIAB so extraction of starch will take longer. Also, just because somebody else might have full extraction and conversion at 20mins doesn't mean you will. So try it for yourself - accurately measure your strike water volume and take a specific gravity (hydrometer) reading at 20 mins, to see if you have full mash efficiency (or close to). If not, it might take 30, or 40 or, like my system, closer to 60 mins for full efficiency.

 

[RM-MN]

A longer mash will generally give a more fermentable wort, as the beta amylase (slower acting) has time to work. Also, beware of these reports of 20 minute conversion - starch in solution converts very quickly, but getting the starch out of the grain takes longer. If these tests at 20 mins were only iodine tests of the liquid portion, they'll show conversion even though there is still starch in the grain. Most mashes are longer because the grains are crushed more coarsely than BIAB so extraction of starch will take longer. Also, just because somebody else might have full extraction and conversion at 20mins doesn't mean you will. So try it for yourself - accurately measure your strike water volume and take a specific gravity (hydrometer) reading at 20 mins, to see if you have full mash efficiency (or close to). If not, it might take 30, or 40 or, like my system, closer to 60 mins for full efficiency.

Lots of information in the highlighted portion. Iodine tests must include and be mostly grain particles to tell you if you have full conversion. You can only get full conversion if the starches are fully gelatinized and for that to happen the grain particles must be small so the starches are exposed to the water. When these starches are exposed and gelatinized the conversion happens very quickly and the enzymes are denatured very quickly too. If this were not so longer mashes such as the overnight mashes some people do would get you wort that would be extremely fermentable but that doesn't happen because the beta amylase is gone, destroyed by the very temperature that it needs to do the conversion.

Long mashes do not ensure complete conversion either. If the particles of grain are too large the starches never fully gelatinize and are not converted, just disposed of with the remains of the mash which is why you see people complain about poor efficiency. Their grains were milled so coarsely that much of the starch stayed dry, locked inside the grain. Some extra efficiency can be achieved by extending the mash to 90 or 120 minutes but with the extra time some of the enzymes are destroyed before they are ever turned on.

Even if your grain is milled to nearly flour consistency I would not suggest you try a mash shorter than 30 minutes even if you have full conversion. It takes a lot more time to extract flavors than to convert starches and very short mashes get you beer with the proper amount of alcohol but little flavor.

 

[Gnomebrewer]

Even if your grain is milled to nearly flour consistency I would not suggest you try a mash shorter than 30 minutes even if you have full conversion. It takes a lot more time to extract flavors than to convert starches and very short mashes get you beer with the proper amount of alcohol but little flavor.

Interesting. I'd never really thought about time affecting flavour extraction. It makes sense though. It would be interesting to compare a minimum time flour mash (30mins?) vs a 60 to 90min mash with the same crush and system.

 

[RM-MN]

Interesting. I'd never really thought about time affecting flavour extraction. It makes sense though. It would be interesting to compare a minimum time flour mash (30mins?) vs a 60 to 90min mash with the same crush and system.

Don't tell anyone I said this but the minimum time for conversion with the grain milled to near flour is....

less than 2 minutes.

 

[Nathan Hassey]

And this is why I was asking the question. It seems like there is mich more to the 60 min .ash than just conversion.

 

[dmtaylor]

Starch is converted quickly to all sorts of complex sugars and dextrins. Most yeast cannot ferment much of that stuff. So the longer mash is indeed for fermentability / attenuation. That is precisely why I mash 40 minutes rather than just 20 or 30. Based on much experimentation I found that I can minimize waste of time on brew day AND still get complete attenuation at 40 min.

 

[RM-MN]

Starch is converted quickly to all sorts of complex sugars and dextrins. Most yeast cannot ferment much of that stuff. So the longer mash is indeed for fermentability / attenuation. That is precisely why I mash 40 minutes rather than just 20 or 30. Based on much experimentation I found that I can minimize waste of time on brew day AND still get complete attenuation at 40 min.

This was not my experience with the grain milled very fine. The 10 minute mash attenuated about the same as the 30 or 60 minute mashes I had done but the flavor was lacking in the very short mashes.

 

[schematix]

A very enlightening test is to test your mash gravity over the course of time.

Each grain has a theoretical 100% extraction and its easily achieved. If you monitor the actual gravity vs max gravity you'll see where your gap is.

I highly recommend reading and really trying to under the information on this page - http://braukaiser.com/wiki/index.php/Understanding_Efficiency#Conversion_efficiency

 

[dmtaylor]

This was not my experience with the grain milled very fine. The 10 minute mash attenuated about the same as the 30 or 60 minute mashes I had done but the flavor was lacking in the very short mashes.

Interesting. I don't mill down to a fine powder, but rather just "normal". My average brewhouse efficiency with a 40-minute mash is 82%. Average attenuation is right where you'd expect, 75%-ish for the average yeast. Flavor is not lacking in any way whatsoever with 40 minutes. I don't do less than that except for rare experimentation.

 

[Nathan Hassey]

Ok, I have to admit I am a little confused now. I thought temperature of the mash determined the fermentabilty of the wort. If i mashed and held a 156F temp, I would have more a fuller bodied beer because of the sugars not being fermentable at that temp. But based on what some of you are saying, if I held 156F for an hour or more, It would lose that full body and start becoming more fermentable? Or are you assuming that with time, comes a lower temp in which case would increase the fermentabilty...I thought if you wanted a dry beer, you hold a lower temp (148-150F) and a fuller bodied beer you raise the temp.

 

[dmtaylor]

Ok, I have to admit I am a little confused now. I thought temperature of the mash determined the fermentabilty of the wort. If i mashed and held a 156F temp, I would have more a fuller bodied beer because of the sugars not being fermentable at that temp. But based on what some of you are saying, if I held 156F for an hour or more, It would lose that full body and start becoming more fermentable? Or are you assuming that with time, comes a lower temp in which case would increase the fermentabilty...I thought if you wanted a dry beer, you hold a lower temp (148-150F) and a fuller bodied beer you raise the temp.

The fact of the matter I think is that we are ALL confused, and it's not our fault. We've been led to believe certain things which really don't matter as much as we've been told. You are correct in spouting conventional wisdom/theory that lower temperatures favor a drier beer and warmer ones kill off the beta amylase quicker and thus should result in a fuller bodied beer. What I'm trying to point out is my belief that temperature matters much less than conventional wisdom has led us all to believe, and total mash TIME matters much more. So then, yes, I think if you mash at 156 F for 90 minutes or longer, you're still going to end up with a reasonably dry beer. I've found that many people ignore the mash time bit and futz around for 90 minutes, or 120 minutes, or more, with rests at several different temperatures, then wonder why they're spending all this time when the beer turns out just as good or better if they'd just do a single infusion for 60 minutes or less. Or even more likely, most people probably don't even think about all this or care and just blindly do whatever rests because someone told them to or because the recipe says so, but haven't experimented to find out what differences it truly makes. I've played around enough to come to my own conclusions, and to anyone interested, I really must suggest that they do the same thing, run experiments and find out, and don't accept anyone's word as truth, because it ain't. I might be wrong about half of what I'm saying and I'm okay with that, I've got my beliefs and everyone else is free to have theirs, but the truth is still out there somewhere in between, and I'm certain THAT is the truth.

 

[Nathan Hassey]

So what I could do is for any given temperature, check to see if 1. Conversion is done and 2. See if the gravity is what is desired?

Say I mash at 156F and i really do want a full bodied beer, then check at 20 min increments and if both conversion and gravity is at goal, start running off. It makes sense. Higher temp means harder to convert sugars which means takes longer. If you stop it at the desired time, then the enzymes wont have time to convert those leaving more behind (fuller body). So really, for a full bodied beer, mash times shouldn't be as long as a dryer beer. If this is what you are saying, I had a huge epiphany today!

 

[El Nino]

Doing a 90 minute mash on average raised my mash efficiency by close to 10% (was getting 60-65% efficiency just double crushing). Hit 70-75% consistently now.

 

[Nathan Hassey]

From what I'm gathering it will because kts giving more time to convert. But if someone wanted a fuller body beer you wouldnt want 100% conversion...unless I'm way off base.

 

[dmtaylor]

So what I could do is for any given temperature, check to see if 1. Conversion is done and 2. See if the gravity is what is desired?

Say I mash at 156F and i really do want a full bodied beer, then check at 20 min increments and if both conversion and gravity is at goal, start running off. It makes sense. Higher temp means harder to convert sugars which means takes longer. If you stop it at the desired time, then the enzymes wont have time to convert those leaving more behind (fuller body). So really, for a full bodied beer, mash times shouldn't be as long as a dryer beer. If this is what you are saying, I had a huge epiphany today!

That sounds like a plan. Yes, if I wanted a big bodied beer, I might mash hot for just 30 minutes then runoff and bring to the boil as fast as I could. This does assume an excellent crush. If you're getting a crappy crush like from your LHBS, then all bets are off.

 

[Gnomebrewer]

From what I'm gathering it will because kts giving more time to convert. But if someone wanted a fuller body beer you wouldnt want 100% conversion...unless I'm way off base.

You'd still want 100% conversion of starch, but not too long so that dextrins don't get broken down to sugars (at least, that's my understanding based on observing the same as the other Dave (I'm also Dave) that longer mash makes a more fermentable wort, even at higher temperatures). As soon as your conversion, measured by checking the gravity of your mash wort, is complete, raise to mashout temps or runoff to your boil kettle and start to boil if you want a less fermentable beer.

 

[RM-MN]

Doing a 90 minute mash on average raised my mash efficiency by close to 10% (was getting 60-65% efficiency just double crushing). Hit 70-75% consistently now.

Find someone else to get grains from. If you get better conversion with a 90 minute mash than 60 minutes it is because the grain isn't crushed well at all. The extra time allows more starch to gelatinize which is necessary for conversion. I can get better conversion efficiency in 5 minutes than you are at 90 minutes with my grains milled very finely.

 

[dmtaylor]

Find someone else to get grains from. If you get better conversion with a 90 minute mash than 60 minutes it is because the grain isn't crushed well at all. The extra time allows more starch to gelatinize which is necessary for conversion. I can get better conversion efficiency in 5 minutes than you are at 90 minutes with my grains milled very finely.

SO much truth! If any man have ears to hear, let him hear!

 

[schematix]

One thing I haven’t seen mentioned here is gelatinization temps, the temperature at which the starch granules make their starch available to be dissolved.

Plays a big part in efficiency. So while the enzymes do their work fairly quickly, they can only work on what’s been made available.

I usually get about 85% extract in 20 minutes at 145. Another 20 at 148 and it’ll creep up a few more percent. Each time I step my temps up I get more starch into solution and converted. I even get another 1-2% just from performing a mash out, which is at a temp way higher than the standard gelatinization temp.

 

[bleme]

One of the guys in my club did a triangle test at the last meeting. He used the same recipe and mashed one for 15 minutes and the other for an hour.

OG on the 1hr was 1.050, OG on the 15min was 1.044, so slightly better efficiency.

I don't remember the exact FG's, but the 15min was much higher as it was less fermentable.

Nearly everyone could taste the difference.

 

[El Nino]

Find someone else to get grains from. If you get better conversion with a 90 minute mash than 60 minutes it is because the grain isn't crushed well at all. The extra time allows more starch to gelatinize which is necessary for conversion. I can get better conversion efficiency in 5 minutes than you are at 90 minutes with my grains milled very finely.

There's nobody else to get grains from where I'm at, so I'm pretty much stuck. I could get a grain mill which I know would improve efficiency but I sorta already have my method down and I'm comfortable with it. 90 mins gives me time to take care of other stuff around the house or play video games lol

 

[Silver_Is_Money]

Demand a double crush. Ask your LHBS to pass it through their grinder a second time.

 

[bracconiere]

I hit 95% efficiency with a step mash? 30min at 150f, then another 30min at 162f....repeatable also....

i add gluco to all my beers so not sure how fermentable it would have been....

 

[Silver_Is_Money]

I hit 95% efficiency with a step mash? 30min at 150f, then another 30min at 162f....repeatable also....

Do you pulverize your grist?

 

[LittleRiver]

There's nobody else to get grains from where I'm at, so I'm pretty much stuck. ...

Anything that even remotely resembles whining from the man who lives in paradise will not be tolerated.

Seriously now, you should get a grain mill. You will not regret it.

 

[bracconiere]

Do you pulverize your grist?

i have a JSP Malt Mill, set to a credit card....or 32 which ever is smaller....before when i just did single step mash at 150-155f i would get 83% efficiency...

i have to do the two step, or now it seems 3 step, protein rest, beta, alpha, with my home malt. But i bought a bag of store bought and did it with it also and got 95%, both batches....