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Mashing - How long is too long?

A buddy of mine started his mash at 8 in the morning then went to work. When he got home his mash had been working for 9+ hours and had dropped from 150 to 135. It seems like a foolish thing to mash that long and suffer that great a temp. drop. Are there any side effects from mashing for this long? I’m heard of a 2 hour mash, but 9?
Thoughts anyone?
S

No harm done. Read up on overnight mash. The important thing is the start of the mash. As long as temps are where you want them when you mash-in and there isn’t too much temperature loss over the first hour, it doesn’t really matter what happens after that.

Oh yeah, forgot to mention; the only real drawback to this method is that it’s a bit harder to get your mashout temperature right. It just requires adding slightly more boiling water to bring the temp up, but there are calculators online to help with that.

Interesting, I figured there would be some kind of set back to hold in that long, but if the first hour is the most important, then after that is just extra time. Does as mash out have any more importance when sitting on a mash for this much longer?
S

Mashout temp really has no effect at the homebrew scale. You can sparge with cold water and get the same efficiency. As far as stopping conversion, that happens as you bring your wort to a boil.

Wort will be more attenuative than if he had done just a 60-min mash, so if it’s a recipe with simple sugars added, might want to dial back on them a little (unless a lower FG is a good thing). With that long a mash, there’s no reason to mashout since the enzymes had more than enough time to chew through pretty much everything they could handle.

I’ve smelled the spend grist the next day and would not want any of the those off smells or flavors in my beer. Bacteria are happy to start on the wort sugars and though the wort is sterilized during the brewing some bad flavors will get through. Why chance it?

[quote=“BarryBrews”]I’ve smelled the spend grist the next day and would not want any of the those off smells or flavors in my beer.[/quote]I’ve overnight mashed many times (great way to make a big Belgian beer with low FG) and never had it go sour - as long as the temp stays up in the 130s it won’t have any off aroma or flavor.

Sorry, this might be a stupid question, but does a longer mash equate to a lower FG, because the enzymes have had more time to work?
So the first hour does most of the heavy lifting in terms of conversion, and any additional time would pick up any of the scraps? Is that the (very) basic fact?
S.

[quote=“Gr8abe”]Sorry, this might be a stupid question, but does a longer mash equate to a lower FG, because the enzymes have had more time to work?
So the first hour does most of the heavy lifting in terms of conversion, and any additional time would pick up any of the scraps? Is that the (very) basic fact?
S.[/quote]

Yep, in general all of that is true.

is there any info out there on how much drop off there is in enzyme conversion over time after 1 hour?
is a 75 minute mash significantly more effective than an hour and a half mash?
S.

[quote=“Gr8abe”]is there any info out there on how much drop off there is in enzyme conversion over time after 1 hour?
is a 75 minute mash significantly more effective than an hour and a half mash?
S.[/quote]

Here’s a link with what seems like mostly accurate information. It’s temperature/time dependent. I think at a certain point you don’t get more statistically significant conversion, but that all depends on your starting temp. There are charts and graphs about half-way down the page that help with the explanation:
http://www.braukaiser.com/wiki/index.php?title=The_Theory_of_Mashing

As mentioned above I’ve overnight mashed lots of times. I’ve also done a cold water batch sparge and let the drained wort sit overnight. No issues either way. Beer ends up great. Downside is that it takes extra time to heat the wort to boiling the next day.

Sometimes, with a busy family schedule, it’s that or no beer.

That is a fantastic article! Thanks!

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