[akr71]

It seems that conventional wisdom is to let the mash sit for 60 minutes.  Why?

A pro-brewer friend of mine insisted to me & others in my brew club that conversion is complete in 15 minutes, unless you are using a large percentage of adjuncts.  He says that is what he was taught in brewing school.  So why waste your time with a longer mash?  

I did an oatmeal stout today with a 30 minute mash and came pretty close to my anticipated OG.  It was the first time with a new (to me) mill, so I'm pretty sure the crush was a bigger issue than mash time for the lower pre-boil OG.  The only reason the mash sat that long was to get the sparge water heated and get some yard work done.

I might let a big beer mash longer, but I can't see me wasting time with a 60 minute mash again.

[euge]

I used to go for 90 but now no longer than 60. I do thinner mashes 1.6 qts per pound and 45 minutes is fine. 

Think I'll try 30 next time and see. Good question.

[bluesman]

The way to be sure is to estimate your theoretical conversion and measure the gravity or sugar concentration.
I use a refractometer for this measurement.  Check the mash at 15, 20, 30, 60 and 90 min.
I have seen data to support the result of a 30 min mash as the cutoff for diminishing returns.
In fact our very own Kia T. has the data on   http://braukaiser.com/wiki/index.php/Starch_Conversion

[timmyr]

Iodine test will tell as well. I had the opportunity to hang out during a brew session with a local pro-brewer and their mash ran just less than 60 min with recirculation to clarify.  I think it is system dependent, but if you get the results you like and can repeat them, then let it ride.

Cheers,

Timmy

[dmtaylor]

I have played around a lot with mash time to try to find out the minimum time I could get away with and still make awesome beer.  The short answer?  40 minutes.  The problem is not conversion -- the bulk of conversion is done in the first few minutes.  But what is greatly impacted is the attenuability of the wort.  You can mash a beer for as little as 15 or 20 minutes, and you can still get decent mash efficiency, but your 1.060 beer might finish fermenting as high as frickin' 1.025 and just stop right there, and no amount of rousing or pitching more yeast will help.  A 30-minute mash time is better, and will attenuate okay about 50% of the time, in my experience.  But 40 minutes, well then it attenuates just fine every time, and you just saved yourself 20 minutes of waiting time per brew day.  If you do wait for a full 60 minutes, you'll only get another gravity point or two of attenuation, so I think the 40-minute mash time is the better way to go, being that it is a great time-saver, with no significant drawbacks.  So that's how I've been making most of my beers, unless I want to eek out every point of attenuation possible, which for some styles is appropriate as well.  So, it all depends on what you want out of your beer.  But attenuation is the effect that you need to look at, not conversion.

[euge]

That is a really great point. So how do you feel about thinning the wort to increase fermentability in combination with this shortened time technique?

[dmtaylor]

I have recently read in multiple sources that the thinner mash = thinner beer theory is an old Papazianism that doesn't hold water.  You can thin your mash as much as you want, and it doesn't make a whole lot of difference, if any.  Now, I wouldn't know that from personal experience as I have still been mashing at my usual ~1.3 qts/lb, but you can try it to see if it makes any difference for you and your system.

[denny]

I agree completely with Dave.  I've mashed from 1 qt./lb. to 2 qt./lb. and haven't found it to make a difference in fermentability.  But I have found mash time to make a difference.  I never go for less than 60 min. and if I'm looking for a really fermentable wort I go 90-120 min.  One thing that's often overlooked when commercial brewers talk about shorter mash times is their lautering time.  It can take an hour or more to sparge and lauter a commercial batch and all that time you're still at mash temp.  So, what would seem to be a 20-30 min. mash actually might go for 90 min. or more.

[akr71]

Thanks for the responses!  I was hoping some people had experimented with mash times.  Sparge temperature and conversion while draining the mash tun were also part of the conversation.

[Thirsty_Monk]

As Bluesman mention one way to experiment with it would be to measure your mash OG at different time.
When your gravity does not go up anymore you are converted.
Also your mash speed depends on Mashing temp.
Higher temp faster conversion.

All that said we should mash our grain to get certian fermentable profile instead of how fast it converts.
This should also apply to commercial brewers.   
Just saying. 

[denny]

Yep, there's a difference between just conversion and wort fermentability profile.

[uthristy]

APA/IPA = 75min mash
Belgian beers = 90-120min mash
works for me

[tom]

Kai has an experiment posted on his site:  http://braukaiser.com/wiki/index.php/Mash_Time_Dependency_of_Wort_Fermentability
Although the fermentability improved, he felt that is wasn't all that much. His experiment was done at 158F.

I have tried shorter mashes with pale ale malt and it required at least a 40 min mash for complete conversion. Lighter-colored base malts may convert more quickly.

[anthayes]

Here is a useful article on shorter mashing times, "To Mash or not to Mash Kurz / Hoch"

http://www.draymans.com/articles/arts/14.html

[bluesman]

Kai has an experiment posted on his site:  http://braukaiser.com/wiki/index.php/Mash_Time_Dependency_of_Wort_Fermentability
Although the fermentability improved, he felt that is wasn't all that much. His experiment was done at 158F.

I have tried shorter mashes with pale ale malt and it required at least a 40 min mash for complete conversion. Lighter-colored base malts may convert more quickly.

From his data it looks like there's a max of 4% increase in fermentability when mashed for 2hrs.
That's not a significant increase AFAIAC.

...but if you have the time and need that additional bump, why not go for it.