Overnight mash tips

[dshar]

I was a bit short of time this weekend so decided to try an overnight mash to split up the brew day.
In the end, I only sparged after more an 12 hrs and the temp had dropped from 68 to 55c.

I use a campinggaz cooler and wrap it with a sleeping bag and other layers of fleece material.

How will the long mash and lower temperature affect the beer? (Hopefully it won't be a disaster, my last brew went down the drain due to an infection!)

Also, any tips on better insulation for the mash tun?

Cheers
D

[beersoulman]

I have done the overnight mAsh a few times with no problem. Roughly speaking I believe that as long as temperature is maintained for the initial say 90 minutes after that it is not critical. Recommendation though is to start at a slightly higher temp ... say 70 degrees? Know what you mean about splitting the brewing day ... the other option is to get up at 6am and go back to bed!


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[dshar]

Thanks soul man. Glad to hear that, I was thinking along the same lines that holding the temp for the first hour or two would be critical, but good to have it confirmed. I was also surprised how much the temp dropped!
I quite liked splitting the day up, otherwise it's pretty much a full on day for me, have never managed to get below 5 1/2 hrs, after which I'm too tired to do anything else

[jaroporter]

Non critical might be subjective. If you come back to a mash after 12 hours and the temperature is still at 68c, or has dropped to 60c, or under 50c you'll have one of three quite different beers regardless of that first hour or two. There's a load of threads with peoples experiences about here, some really good info on overnight mashing

[orlando]

The temperature can fall to the point acetobacter wakes up and sours it. Your nose will tell you so give it a good sniff.

[dshar]

Ok, so it's more complicated than I thought. Thanks for the input, I'll search around on the forum for advice. Suppose I just need better insulation...
It's bubbling away nicely now, and smells ok, so fingers crossed!

[orlando]

The temperature can fall to the point acetobacter wakes up and sours it. Your nose will tell you so give it a good sniff.

EDIT: Correction Lacto Bacillus, but amounts to the same thing.

[rpt]

As long as the temperature stays above 50C you should be ok. I have done many brews this way and have not had any sour beers.

[orlando]

As long as the temperature stays above 50C you should be ok. I have done many brews this way and have not had any sour beers.

I've heard of people sticking the MT in their oven overnight.

[dshar]

It stayed above 55c and I think it was something like 14hrs
So it's hopefully not a write-off.
The split day work well for me, I just read the 'using my time effectively' thread and some good tips there too. I might try the mash n sparge the night before variant next time. Seems potential downsides with that method are less (possible slight souring due to bacteria).

[beersoulman]

Just do it. Craft not science!


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[charliemartin]

To reduce heat loss you can cut a piece of Kingspan insulation to fit your mashtun, cover it with tin foil and clingfilm and put it on top of your mash. Helps to reduce heat loss into the headspace in your tun.

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[orlando]

You can go further if you like. When I had an igloo MT I decided to make a Kingspan box. I sat the MT on one piece and built a box to slip over the top.

[andyCo]

The temperature can fall to the point acetobacter wakes up and sours it. Your nose will tell you so give it a good sniff.

EDIT: Correction Lacto Bacillus, but amounts to the same thing.

Butyric acid , you'll know it when smell it's like vomit,Parmesan cheese and all things stinky.
This happened to me and like a fool I boiled the wort thinking I could kill any bacteria @100c.....oh no it stank the brew shed out forever until I sprayed with some form of chemical and had to repaint and seal the inside of the shed.


Andy