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.

maida7 said:

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?

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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.

RM-MN said:

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

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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.

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.

troub said:

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.

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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?

JesseL said:

so the boil on the following day should kill off any hitchhikers.

I'd rather find a way to accommodate AG brewing than go back to extract.

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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.

I've done it before (mash on day 1, boil on day 2) without any issues. Although maybe I just got lucky because it's possible that any wild yeast, etc., can sour the wort overnight.

maida7 said:

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

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Now THAT is an inspiration! My hat is off.

I have set up the mash tun at 9:00 or 10:00 at night and let the mash sit overnight. I am up by 7:00am to get the party started and have never had any issues. i don't do this every time but I would say 30 times over the last 4 years. I have never had any issues with efficiency or sour taste in the beer. I have purposely brewed beers that I am very familiar with the check those issues. For me at times it is the only way I can brew. I travel 17 weeks a year - married with 3 kids - busy house

BillyBeer said:

I have set up the mash tun at 9:00 or 10:00 at night and let the mash sit overnight. I am up by 7:00am to get the party started and have never had any issues. i don't do this every time but I would say 30 times over the last 4 years. I have never had any issues with efficiency or sour taste in the beer. I have purposely brewed beers that I am very familiar with the check those issues. For me at times it is the only way I can brew. I travel 17 weeks a year - married with 3 kids - busy house

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I know this thread is very old, but hopefully someone will respond. So in the quote above am I right in that you basically dough in at 10pm and let the mash do it's thing for about 9-10 hours?

In other words, if your target mash temp is 153F, you mash in to temp and close the lid and go to bed. Then in the morning you drain and sparge. Then you boil?

For everyone else who is saying that your beer will sour, how is what the quote above any different than mashing, sparging and putting the wort aside until the next evening? Thanks for helping me out!

bizarrojosh said:

For everyone else who is saying that your beer will sour, how is what the quote above any different than mashing, sparging and putting the wort aside until the next evening? Thanks for helping me out!

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If you sparge on the first day, you can pasteurize the wort by heating to to 170F on the stove before going to bed.

I have in the past mashed, sparged and collected pre boil volume at night then finished of the process in the morning before the kids get up, works fine, just covered the kettle in blankets to retain some heat.

I have left my wort in the boil kettle for close to 12 hours BEFORE the boil. I didn't want to by any means but emergencies happen that you can't control. So I just leave the lid on it and put it in my keggerator tell I could get to it. I finished the beer and I didn't get any off flavors or sourness. In fact the beer is one of my best according to friends and family. I am by no means saying to do this every time do to bacteria, but you never know tell you try it. Do a SMASH brew and see how it works out. There is only one grain and one hop in them so it would be like $12.00 to find out.

Here's an update, in case anyone's interested. I just opened my first beer from this batch where I mashed and lautered the night before. I was done around 9:00 p.m., left the kettle on the stove, and started up for the boil about 7:00 a.m. the next morning. No off flavors, no souring, just a really good beer. Seeing as I have twins, a full-time job, and a freelance job, I'm going to be doing it this way from now on.

By the way, I've heard lots of people say that souring could happen. Is there anyone out there who has a first-hand account of sour beer from a full kettle left overnight pre-boil?