Very Very long Mashing time?

[The Baron]

I usually do overnight mashing by mashing then wrapping the boiler so that early morning it is still reasonably warm and I can carry on with the rest of the brew day.
Unfortunately work is getting in the way and I am thinking of mashing (with recirculation) for 12 to 15 hours thats is just leaving it at the mash temp alone so that it is still at temp when I get home from work. Has anybody else done this? and what may be the pitfalls?

 

[An Ankoù]

In my experience, overnight is just long enough. As the temperature drops, the lactic acid bacteria begin to take a hold and I often get a bit of a whiff when I take the lid off in the morning. Optimum temperature is around 20-35C and they're serious endangered at around 72C. As I tend to mash around 65C and then let the temperature drop. I have to be careful. if you're keeping the temperature high you might be ok or you might get more tannin extraction.
I'd say, try it and let us know how it works out.

 

[The Baron]

Thanks AA you do more or less exactly what I normally do so as not to get the dreaded Lactobacillus at lower temps.
I think I will try it but its going to be in the region of keeping it warm from the previous night till I get home from work at 2.30pm so I will do it and report back just wonder I would get some burning on the bottom of the All In One, mind you it will clean off as long as it does not taint the wort

 

[peebee]

I've not got into over night mashing, but have begun to do something similar:

First off, you don't have to worry about sugar extraction getting unbalanced. The enzymes can't tolerate the temperatures we mash at for very long and will have packed up early into the night. Alpha amylase keeps going the longest which will just ensure no starch hazes (but I don't believe anyone suffers from these?). The point being it's not essential to hold exact mash temperatures all night.

What I'm doing is completing the mash in the normal time (say 90 minutes), lifting the malt tube (all-in-one systems like Grainfathers make this method really easy), set the temperature to rise to 80°C (pasteurise?) while doing any sparging (I do "full-boil-volume-mashes" in the GF so don't need to bother with late-night sparges), then remove the malt tube and switch off. Recommence with the boil next day.

If this method results in rubbish beer (why should it?) I don't know yet 'cos the brews I've done like this ain't ready yet.

 

[pilgrimhudd]

Some of my overnight mashes have been around the 12 hour mark with no ill affect, I do keep the heat on, generally set at 65 to give it some leeway.

 

[peebee]

... What I'm doing is completing the mash in the normal time (say 90 minutes), lifting the malt tube (all-in-one systems like Grainfathers make this method really easy), set the temperature to rise to 80°C (pasteurise?) ...

Don't be tempted to hit the boil before turning off for the night. That will dump even more break protein into the boiler which might cause a problem getting a boil going next day (burning?). "Pasteurising" should be enough (75°C?).

 

[The Baron]

Thanks PeeBee I never do the boil until the next day. I am thinking of starting my Mash earlier in the evening than I normally do and sparge it pasteurising then leaving until I can boil it the next day or the original plan of a very long mash in fact I may do both to see which gives the best results

 

[The Baron]

Update I have done a 14 hour overnight heated mash last night and it seems to have gone ok. The Efficiency is bang on my recipe writing example of 70% BHE but on a standard overnight I generally get 75 to 80 % so down in real terms which surprised me.
I did a very close to full volume of 25l (I normally have the re-circ pump on but not on this)against a normal of 20l and only sparged with 4l.
Maybe it was just one of those things but also could be because of no recirculation why the expected Eff was down but all seems well with the wort upto now.
I put in more water to combat the lack of re-circ and to try and stop any burning on the bottom as it was on for 14 hours but there wasn't any more than normal the thing is I forgot the Protofloc Doh!

 

[Redgrave_3]

Not really relevant to the discussion about AIO but I did an overnight mash once that ended up being 17hrs (due to a hangover), this was in a cool box which according to my readings only lost about 4 degrees. It was a saison that finished up at .06 and was delicious.