[noonancm]

Other than not to mash for over 10-12 hours because it would lead to sour beers, I was wondering what would be the effect of mashing for say 3 hours.

The reason I ask is that occasionally like I had to leave the mash tun for about four hours (Today it was church and brunch with the family). I mashed in at 154 and returned to mash out at 150. For what it's worth I am brewing in this case a Blond Ale.

I was just wondering. I had done some searching but came up with no real answers.

[uisgue]

I don't see any problems with that.  You might find it to be somewhat more fermentable than it would be with a shorter mash time.  With a very high OG beer, it can be a good idea to extend the mash time to maximize fermentability so as not to end up with an excessively high final gravity.

[tom]

+1
But dude,  you really have to get your priorities straight!  Church and family?   

[jdvisger123]

I think you will be fine... just wondering how you kept the mash temp that high for that long. I don't think that it will be more fermentable as you did hit the proper mash temp for conversion. Grains are more modified these days and usually convert within  20 to 30 minutes as validated by BYO/ BBR experiments. We usually conduct a one hour mash as a result of habit more than anything else.
Now lets say that your mash temp drooped to 110-120 degrees. Fermentables would start to solidify and your efficiency would suffer greatly. Not sure what the end result would be...
JMTC

[Jimmy K]

Try it! Some decoction mashes take hours to complete, so you're at low risk for doing something wrong I say. Actually, sounds like you've already done the experiment.

[malzig]

Grains are more modified these days and usually convert within  20 to 30 minutes as validated by BYO/ BBR experiments.

I can't find that issue at the moment, but my recollection of the results is different than yours.  Didn't they show that, while an iodine test is generally negative for starch by 20-30 minutes, conversion continues for an hour or more when measured by gravity increase of the wort.

[liquidbrewing]

FWIW,  I wouldn't worry about mashing that long.  I kinda do the same thing you do, mash in then I'll leave for about three hours when I brew on Saturday morning.  Honestly my efficiency went from high 60's to high 70's, by doing this.  So even if I"m not leaving I always mash for at least 90 minutes. 

I'm sure someone else will chime in here, but mashing is not like cooking water.  You can boil water then cool it down, it's still water.  However, I recall someone else on here talking about how mashing is like cooking an egg.  Once it's cooked to a certain temp (over easy, medium, hard)  then that's it, you can't change it.  Once you release those enzymes from the grain they can't be changed.  If I understand it correctly, you can't mash high to get more flavor, sweetness, etc..then let it drop or temper it down to 150 to maximize fermentability. 

I always mash low, no matter what beer I'm brewing.  I prefer dry beers and have mashed as low as 145 on some IPA's, for 90 minutes or more.  Just sayin...

[hopfenundmalz]

I think you will be fine... just wondering how you kept the mash temp that high for that long. I don't think that it will be more fermentable as you did hit the proper mash temp for conversion. Grains are more modified these days and usually convert within  20 to 30 minutes as validated by BYO/ BBR experiments. We usually conduct a one hour mash as a result of habit more than anything else.
Now lets say that your mash temp drooped to 110-120 degrees. Fermentables would start to solidify and your efficiency would suffer greatly. Not sure what the end result would be...
JMTC

Conversion is done in 15-20 minutes.  The iodine test shows the absence of starch.  It does not show the composition of the sugars.  Long chain dextrines are still being converted to simple sugars if you go longer.

IIRC the beers from the shorter mash were judged to be of less quality than the one hour mash.
http://www.basicbrewing.com/index.php?page=radio  March 3 2011 show.

[tomsawyer]

A 15% sugar solution will start to solidify at 110F?  I dont think so, and in any case the sparge would quickly redissolve things.

Also, in a few hours most MLTs will not drop more than 15F.  I can leave mine overnight and it is still 110F+ the next morning.

20min might show OK on an iodine test but the test doesn't show whats happening on a large piece of starchy endosperm.  Its not done converting in 20min.