Oversteeping grains in the mash?

[rinhaak]

I'm still learning the ropes of all grain brewing having just brewed my second AG last night (with a depressing 46% efficiency; but that's not the topic here!)

I'm curious what would happen if I let my grains steep at 155° (or whatever my chosen temperature) for longer than an hour. Say I let it rest for three or four hours? I'm using a water cooler, so after four hours it would be reasonable to assume that my temp would have gone down a little, but I can't imagine by much.

And supposing I don't stir it during that time. What chemical process would I be stopping or creating?

 

[usfmikeb]

I'd imagine that would leach tannin from the husks, and wouldn't advocate doing it. You'll improve on efficiency with practice. What kind of thermometer are you using, and how accurate is it? Also, 155 is a bit high...

 

[rinhaak]

I'd imagine that would leach tannin from the husks, and wouldn't advocate doing it. You'll improve on efficiency with practice. What kind of thermometer are you using, and how accurate is it? Also, 155 is a bit high...

155° was really a random number. The beer I made last night was a Hefe and I rested at 117° (supposed to be 111° but I overshot and didn't have any ice; another rookie mistake) for 30 min, and 153° for 75 minutes. The thermometer is pretty accurate as I've tested it against others and it's always pretty spot on. Don't recall the brand name off the top of my head, but it came with my first brew kit way back when.

 

[El_Exorcisto]

You can mash for as long as you want. As long as you keep it below 170 and your mash pH isn't too high the risk of leeching tanins is no-existent. You just don't gain anything once you have complete conversion.

 

[mcaple1]

I'd imagine that would leach tannin from the husks, and wouldn't advocate doing it. You'll improve on efficiency with practice. What kind of thermometer are you using, and how accurate is it? Also, 155 is a bit high...

155 is a bit high....in what brewing world would 155 be high??? Dooood......yes, you can mash for that long, but the conversion has undoubtedly already completed within 90 minutes at that temp....faster at lower temps. Mashing for 3 hours is just a waste of time and an insult to the beer gods.

 

[mabrungard]

155F is high only if the thermometer reading it is inaccurate. 158F to 160F is getting on up there. 155F is just closer to the edge.

The extended mashing time improves the fermentability of the wort. Sometimes that is not desirable if you're looking for more sweetness and mouthfeel in the finished beer.

Things to consider with respect to efficiency. Are you sure the accuracy of the measurements are good? Water volume, malt weight, gravity readings? Any of those items can make it look like your efficiency is off. Is the grist ground too coarsely? That affects efficiency. And don't assume that those other thermometers are reading properly if they are not calibrated properly. PS: you can't assume that a thermometer is calibrated in the typical mash temp range if you checked it at freezing and boiling. If you can compare to a NIST-calibrated mercury or alcohol thermometer in the mash temp range, that would be much better.

The other thing that really affects efficiency is the speed at which the wort is run out of the mash. Slower is always better if you're fly-sparging. It should take at least a half hour and an hour is better yet.

 

[rinhaak]

The other thing that really affects efficiency is the speed at which the wort is run out of the mash. Slower is always better if you're fly-sparging. It should take at least a half hour and an hour is better yet.

This I didn't know. This is helpful.

I've mainly been interested in potentially mashing and letting it sit to help optimize my own daily schedule. For example, I don't often have a full 5 hours or whatever in the evening to brew. If I could set up the mash in the afternoon, leave for work, then return in the evening and start brewing, I could have many more brew days available to me.

Seems as though the general consensus is that that would be OK.

 

[Yooper]

155 is a bit high....in what brewing world would 155 be high??? Dooood......yes, you can mash for that long, but the conversion has undoubtedly already completed within 90 minutes at that temp....faster at lower temps. Mashing for 3 hours is just a waste of time and an insult to the beer gods.

155 isn't really that high, depending on what you're making. I mash many, many beers at 154.

I've mainly been interested in potentially mashing and letting it sit to help optimize my own daily schedule. For example, I don't often have a full 5 hours or whatever in the evening to brew. If I could set up the mash in the afternoon, leave for work, then return in the evening and start brewing, I could have many more brew days available to me.

Seems as though the general consensus is that that would be OK.

Several guys have posted about an overnight mash. That would work best if you preheated your MLT and had an MLT that held heat very well, like a cooler. I've never tried it, but if time is precious to you, you could try that. Mash in at bedtime, batch sparge in the AM and start your boil.

 

[barshnizza]

I second the sparge speed thing. I jumped 10% in efficiency when I slowed it down. Milling my own grain has increased it even more

 

[Ryush806]

Several guys have posted about an overnight mash. That would work best if you preheated your MLT and had an MLT that held heat very well, like a cooler. I've never tried it, but if time is precious to you, you could try that. Mash in at bedtime, batch sparge in the AM and start your boil.

Joe Formanek (in side blurb in Gordon Strong's book Brew Better Beer) talks about doing an overnight mash in an oven. Just set your oven to 150-whatever, hit your mash temperature and pop it in there. Keeps your mash nice and warm for you to sparge in the morning.

 

[mcaple1]

155 isn't really that high, depending on what you're making. I mash many, many beers at 154.

Im confused....are you agreeing with me Yoop? that was my point exactly

 

[usfmikeb]

Perhaps other is the difference in what others are brewing, but I cannot recall the last time I mashed above 152...

 

[rinhaak]

Joe Formanek (in side blurb in Gordon Strong's book Brew Better Beer) talks about doing an overnight mash in an oven. Just set your oven to 150-whatever, hit your mash temperature and pop it in there. Keeps your mash nice and warm for you to sparge in the morning.

what are you mashing in that you could put it in the oven? I've got a water cooler, but I don't know that I have any pot big enough. And how do you drain the wort from a pan?

i'm confused...

But I do think I'll try the long rest for the next beer.

 

[usfmikeb]

Perhaps other is the difference in what others are brewing, but I cannot recall the last time I mashed above 152...

Murphy's Law kicking in here. Brewing a batch of my wife's porter today, and the mash temp is 154. LOL!

 

[Ryush806]

what are you mashing in that you could put it in the oven? I've got a water cooler, but I don't know that I have any pot big enough. And how do you drain the wort from a pan?

i'm confused...

But I do think I'll try the long rest for the next beer.

I don't actually do this. If I wanted to though I imagine I would use my 10 gal boil kettle BIAB style.

 

[DrLongshot]

For the overnight brewing process, I just wanted to clarify that I do not hold the mash overnight in the oven.
I use an 8 gal ceramic stockpot for my mash tun. This size fits perfectly in an oven with only the bottom rack in place. I then allow for conversion at whichever temp that I am using for the particular brew, then take the kettle out, heat it up for mash out, then lauter and sparge. It is this wort that I then keep on the stovetop for boiling the next morning.
I would highly suggest against keeping you mash going all night before mash out and lauter.
Cheers!
Joe