Separate Mash Day & Boil Day?
 

I'm a recent and total convert to AG, but as a father of 3-year old twins with a full-time job (and a one hour commute each way) I'm having a hard time finding the 5-6 consecutive hours in my schedule for a brew day. I'm considering breaking up the process, ie. conducting the mash, sparge, and lauter the night before and doing the boil the next day. Is there any reason why I can't let the fresh wort sit overnight?

I think you'd need to bring it to a boil to stop conversion and also kill any lactic bacteria. Why not just do an extract brew?

The reasons I can think of are wild yeast, mold and bacteria.

A clarification: I'm thinking of making the wort on day 1, and then boiling on day 2. The wort will sit overnight pre-boil, so the boil on the following day should kill off any hitchhikers.

I considered this, but what I love about all-grain is the greater control over the final product, the reduction in cost, and the deeper involvement in the entire brewing process. It also opens up a whole new realm of brewing geekitude that isn't available with extract brewing. For these reasons, I'd rather find a way to accommodate AG brewing than go back to extract.

I did that the other day as it was too cold to get a boil going. So, I covered the wort in the kettle and continued on with the boil on the next day when it was warmer. That brew is currently fermenting so I can't tell you how it turned out, but i'll update when I find out. FWIW, the hydro sample tasted pretty normal.

This is true, but the idea is that those would be taken care of in the boil. The big problem, I think, is that it might start to sour or take other unpleasant or unpredictable characteristics overnight. The grain in the mash is going to be COVERED in lactobacillus at the least, so it's not an issue of "if I seal it up nothing can get in to infect it." It's already there, from the grain itself. Actually, I've heard that people sometimes let the mash sit overnight on purpose when they want to take a "shortcut" of sorts to making a sour beer. The mash will sour overnight, then the beer will have a sour tang immediately after a normal brewing and fermentation, rather than the typically longer and maybe riskier aging/souring process from pitching the bugs into a "healthy" wort/beer (if you're souring the mash, once it gets about where you want it via pH or taste measurement, the boil stops all further souring).

Anyway, don't do it unless you like sours.

EDIT: by "let the mash sit overnight", I'm not sure if they actually leave it in the tun all night, or if they go ahead an sparge and let the wort sour, or if it matters. I assume they let it sit in the tun, to maximize contact between the wort and the bacteria, but even if you sparged it out into a kettle you're rinsing some bacteria into there along with the sugar, so while the effect might be less, it's still a huge unpredictable factor.

Right- the problem isn't that the nasties are killed in the boil the next day, it's that you will have a sour mash before the next day. Boiling it will keep it from getting more sour, but not counteracting the sourness from sitting out overnight (or even in the fridge as it would take a long long time to go from mash temp to fridge temps).

Have you considered an overnight mash? If you use a cooler for an MLT, that would probably work pretty well. Maybe mash in at 10 PM and sparge in the morning and then boil. I know a few others have done it and like it.

Why not?
 

I can't see what would be wrong with it. It's safer than boiling THEN letting your wort sit, which is pretty common practice. You can take advantage of the time to get a yeast starter ready. It's hard to imagine wild yeast/bacteria doing damage that would survive boiling and hopping after only 24 hours.

Ah, I wasn't aware of that. I found a thread on a related topic that mentioned bringing the wort to 200 before letting it sit overnight, as that would kill off the lactobacillus and reduce the souring. What do you think?

The "hitchhikers" would make your wort sour overnight. Best to bring it to a boil before you let it sit overnight.

Extract ain't that bad. Great beer is made in fermentation. IMHO making wort is not as big a deal as everybody makes it out to be. But it's your hobby so do whacha want.

FYI, I'm a single dad with 3 kids, full time job, etc... I brew 10 gallon batches to save time. :mug: