Splitting brew day

[Adrian Gresores]

I'm going to brew this weekend, but, on both days, I will be busy for about half the day. I use BIAB, and I was wondering about getting through the 60 minute mash, pulling the grain, covering the kettle tightly, and continuing with the boil the following day. I have read some concern about the growth of bacteria in the sweet wort in the 120 - 140F range, but I wonder if this is a real-life problem.

Does anyone have any experience or advice in this situation?

Thanks.

 

[White Haus Brews]

I did an overnight BIAB mash a few months ago. I mashed in, insulated the kettle with some reflective and covered with an old sleeping bag in my garage. Didn't get back to it to mash out until 15 hours later the next day and it had only lost 14deg F and absolutely no problem with bacteria or off flavors. I would not hesishes to do it again. Cheers!

 

[GFHomebrew]

Good ideah id pause before boil that way if any bacteria got a foot hold youd boil em out in 60 mins- if lacto well call it a semi sour. Ive walked away from a mash for 5 hours and came back and recomenced brew day. Go for it i say!

 

[okoncentrerad]

I've been doing split brew days for my last 10 or so brews. I haven't noticed any issues yet. Sometimes I've brought the wort up to a short pasteurization rest after mash, but not on all... can't explain why recently I've left the kettle (I mash in kettle) on stove afterward but I've also put the kettle in a cold water bath until next morning.

 

[Ozarks Mountain Brewery]

it really depends on the humidity, wont work in my area 70% is common here and 90% happens all the time, I absolutely hate it

 

[ChicoBrewer]

Not saying it would happen but I had a brew day one Saturday where I thought I had yeast but no yeast. Lhb was closed and didn't open until Tuesday. By the time I got to pitch the yeast I already had a layer of bubbles on top. Turned out sour. My son said it tasted like a saison but I think it tasted like smelly socks. He wouldn't take it so I tossed it.

I'm sure you will be fine since your going to boil.

 

[Nosybear]

Chill the wort below about 80 degrees and do not aerate and you should be fine. It's Lactobacillus that likes it warm and aerobic. The bacteria that work at cooler temps are aerobes, so as long as you don't aerate and keep it cool, you should be golden.

 

[White Haus Brews]

Another thing to keep in mind when creating your recipe for this if you leave it overnight with the grains in you'll likely get a small boost in efficiency. I went from an average of 70-75 up to a little over 80% the brew I did this with and I've heard it's very typical with other people too.

 

[The Brew Mentor]

Can you do it and will it make beer? Sure. Now, is it beer you like and or are trying to produce, that's debatable.
In the waiting time, thing are happening and in the end make a different beer even if it's not an astounding difference.
If I had to wait for a longer period of time, I'd likely bring it to pasteurization temperature, then cool it quickly to sub 40° without aerating ( as Nosy said) and hold it there until you are ready to finish. This really is counter productive though.
Whatever you do, take notes and share with us your results.
Good Luck,
Brian

 

[White Haus Brews]

Here's an experiment that was run on a side by side batch one that was mashed overnight and one mashed normally. In the end the people that they had taste test couldn't tell which was which
http://brulosophy.com/2018/01/08/mash-length-overnight-vs-60-minutes-exbeeriment-results/

There are also many more anecdotal reports in the comments below. You can make just as good of beer and you don't need to go to any extreme measures to avoid contamination. Happy brewing!