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How long can I leave mash in mash tun?

I was planning on brewing a pale ale Sunday morning. After my todays basketball gamesI now have a conflict. Between my son and daughter, games will start at 9:00am and will not end until 4:00pm at the earliest on Sunday. If I were to start mashing at 8:00am and let it sit until 6:00pm, what problems would I encounter? I am a batch sparge brewer.

i’ve never done it. but ive read about people doing a ‘overnight mash’ (the hours you would be absent would resemble a ‘overnight’ scenario). you can probably search this forum for info, or maybe google.

i found this. might have some answers ... t-mashing/

Longer mash and lower mash temperatures both contribute to a lower FG and thus a drier beer. Depending on what you are brewing, that could be either a good or a bad thing.

One process-related item you might encounter is a slower run off due to the lower temperature and thus higher viscosity of the wort. If your grind is very fine, or if you have substantial amounts of wheat, rye or adjuncts present, that could be enough to push you into a stuck sparge situation, though you would probably need to be right on the edge of that to begin with to have the long mash make a difference.

I have mashed in my cooler overnight. It worked fine. I would leave it at 155 and in the morning it would be at 150.

Another Idea,
Could I run my wort off into my boil kettle at 10:00 am and leave it until 8:00 pm for the boil?

Yes. Just keep the kettle covered and you’ll be fine.

Sure, but I’d leave it in the tun instead. Assuming your tun is insulated, you’ll lose less heat that way.

If you don’t want to worry about changing the fermentability of the wort, you could run it into the kettle, bring it to a boil, then kill the burner and resume the boil later. That would have the added benefit of pasteurizing the wort.

I am probably going to end up doing one of these methods on Friday night/Saturday morning. I am brewing up a Schwarzbier and due to plans on Saturday and Sunday, I need to get a jumpstart on it Friday night. Are there any pros and cons that support one method over the other?

I don’t know about pro’s and con’s…I do know, however, from personal experience that doing the run off one day and doing the boil the next works with no apparent problems. I’ve even gone three days between the run off and the boil without any noticable problems…not that I’d recommend it but just to note that it can be done.

Take reasonable precautions to make sure that the container you’re storing the wort in (i.e. boil kettle, carboy, bucket) is clean and covered and you’ll be fine.

I know that some folks recommend bringing the wort to a boil before storing it, but I never have done this and had no problems. The temperatures and lenght of time of a normal mash “pasteurizes” the wort (google “Low-Temperature-Long-Time pasteurization”) so the pre-storage boil is unnecessary.

Unless you do a mashout, the wort left in the MT overnight will be very attenuative, which can be either a pro or a con depending on what beer you’re making. If you want to lock in a fermentability profile or would like a shorter brewday, then draining and boiling and covering overnight is the way to go. I’ve done it both ways and just use the one that’s the best fit for the beer and/or the schedule.

I am brewing a schwarzbier. I think I am going to mash and sparge and then let the wort sit in the kettle overnight. With 2 small kids I am usually up early anyway and most of the time go to bed late because I try to get things done after we put them down for the night. The wort would probably only be in the kettle for 6 hours or so before I get the boil started.

I’ve done this exact same thing twice, for the exact same reason (two kids, bedtimes, etc.). No noticeable difference between the “split” and “normal” brewdays with regards to the quality of the finished product.

Sadly…I still have not brewed the Schwarzbier. I have the grains and hops ready to go and the yeast from the Maibock has been harvested and is waiting for a starter to get it going. The holidays snuck up on me and I am now in Oklahoma for another day or so. Headed back to Dallas for a day or two before heading home Saturday. Have a “Stoutapalooza” of sorts planned for Friday evening in Dallas with a couple of homebrew buddies. I have about 8 or 9 different imperial stouts including The Abyss, St Arnolds Pumpkinator, Jester King Black Metal and Dark Truth that we plan on opening and sampling that night. Should be fun. I hope to get to that Schwarzbier sometime next week.

If you know you’re going to mash for a long time, you can do a few things to counter the attenuative situation. One is to use more crystal, another is to start the mash at a fairly high temp like 158F. The crystal will contribute more sweetness and somewhat more unfermentable sugars, and the high initial mash temp will kill some of the beta amylase and maybe give you a beer with a higher FG.

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