Ok to mash up to 3 hours?

[Wooden]

Is it Ok to mash up to 3 hours?

I use an IGLOO 5 Gal tun, it will be pretty full.
Reason I ask is I want to brew but have an appointment come up from 1-3.

Thinking I would start the mash-in around 12:30, go to the appt. and then get home and start lautering by 3:30.

The beer I have in mind is a clone of a commercial pale/session ale. My plan is to hit a target mash temp of 152 and place the tun inside while I am out so it doesn't lose heat.

Any drawbacks to this? Should I just bite the bullet and start mashing after I get back? There is not really a possibility of me being gone for more than 3 hours.

Thanks,

Wooden

 

[LLBeanJ]

You will most likely get some very highly fermentable wort that will result in lower than expected FG.

 

[kombat]

I've mashed overnight before (8+ hours) and not had any problems. The key is to keep the mash temperature as stable as possible. In my case, I wrapped the boundary of the cooler lid with cling-wrap to minimize air exchange, then wrapped the whole cooler in a sleeping bag. I only lost about 8 degrees overnight (dropping from 154 to 146° F), and the resulting beer was delicious.

I've heard that below 140° F is the "danger zone" where you can start to get undesirable contaminants that will sour your mash, so it's best to keep the temperature comfortably above that threshold, if at all possible.

 

[RM-MN]

I've mashed overnight before (8+ hours) and not had any problems. The key is to keep the mash temperature as stable as possible. In my case, I wrapped the boundary of the cooler lid with cling-wrap to minimize air exchange, then wrapped the whole cooler in a sleeping bag. I only lost about 8 degrees overnight (dropping from 154 to 146° F), and the resulting beer was delicious.

I've heard that below 140° F is the "danger zone" where you can start to get undesirable contaminants that will sour your mash, so it's best to keep the temperature comfortably above that threshold, if at all possible.

Since your mash should be starting above the pasteurization temperature your mash shouldn't sour if you don't get additional bacteria in. Just keep the lid on and the bacterial will have a hard time getting in.

Is it Ok to mash up to 3 hours?

The enzymes that do the conversion are denatured at mash temps and should be all done before your mash has a chance to cool enough to make your wort more fermentable than desired. They just can't take the heat for very long.