Pros & Cons of the mashout - Fact or Fiction?

Ok, so when I'm doing a flay sparge and if I start pre-heating the runoff as it falls into the keggle, by the time (60mins?) the runoff is complete I could very well be close or at boiling temp. If I wanted to get my pre-boil gravity, how much will the value be off if its already boiling? I know its not really all that important, as my #'s are pretty consistent unless I've upgraded the brew machine like I did recently and everything needed re-established in Promash. Its just a "feel good" value. OG/FG are the real #'s to watch I guess. On top of that I guess my ATC Refractometer will read a "pretty close" number to make sure I'm on tract.

Snafu said:

Ok, so when I'm doing a flay sparge and if I start pre-heating the runoff as it falls into the keggle, by the time (60mins?) the runoff is complete I could very well be close or at boiling temp. If I wanted to get my pre-boil gravity, how much will the value be off if its already boiling? I know its not really all that important, as my #'s are pretty consistent unless I've upgraded the brew machine like I did recently and everything needed re-established in Promash. Its just a "feel good" value. OG/FG are the real #'s to watch I guess. On top of that I guess my ATC Refractometer will read a "pretty close" number to make sure I'm on tract.

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All hydrometer samples must be cooled to under 90 degrees or so- and then the temperature conversion tables can give you a good estimate. I just stick my hydrometer sample jar in a pitcher of ice water, and it cools quickly enough. You could stick it in the freezer if you have a freezer handy where you are brewing. A refractometer is nice for this- as a drop of wort cools quickly so no cooling is needed.

Once you know your preboil OG and volume, you can easily calculate your post boil OG.

Snafu said:

Ok, so when I'm doing a flay sparge and if I start pre-heating the runoff as it falls into the keggle, by the time (60mins?) the runoff is complete I could very well be close or at boiling temp. If I wanted to get my pre-boil gravity, how much will the value be off if its already boiling? I know its not really all that important, as my #'s are pretty consistent unless I've upgraded the brew machine like I did recently and everything needed re-established in Promash. Its just a "feel good" value. OG/FG are the real #'s to watch I guess. On top of that I guess my ATC Refractometer will read a "pretty close" number to make sure I'm on tract.

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I'm not sure I understand your question. Your asking how much your gravity will be off by? Off of what?

Snafu said:

...If I wanted to get my pre-boil gravity, how much will the value be off if its already boiling? On top of that I guess my ATC Refractometer will read a "pretty close" number to make sure I'm on tract.

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Trust your refract...exactly what it's for. As Yoop said your hydrometer reading will be WAY off unless you cool it & correct for temp. (think hot maple syrup vs cold maple syrup...very different viscosity).

And correct your volume measurement for temp too...reduce by roughly 4% at boiling.

This is a great thread, btw.

Ok, let me back up. I'm looking at the pros and cons of a mashout. My system is pretty much dialed in and very consistent on OG/FG and hitting targets. One my last batch I opted to not do a mashout in order to gain additional volume for the mash to help control pH. That being said, I was commenting that the #'s didn't really change for me, comparing the readings from prior batches where I did do a mashout. While the whole mash-out/no mash-out question seems to be a matter of personal choice as my #'s didn't change, what I did learn was that the lag time in getting the boil off could change the beers profile as the enzymes continue to break down starches well after the mash was done and the best way to stop that was the mash-out. To "lock" in the profile.

The whole mash/no mash (for me) will depend on the pH I need to control (esp with alot of crystal malts), that being said, and turning focus on the runoff, I currently allow the kettle to fill 100% before I light the burners for the boil. The only reason for this was for me to get a pre-boil gravity reading. If I change my process, to start heating the runoff before the sparge is complete, there is a chance the runoff will be at or very near boiling temp as the fly sparge takes about an hour.

Now to bring in my above mentioned question, since the runoff will already be at or near boiling temp once the sparge is done and I go to take my "pre-boil" gravity reading, how will the fact that I'm at or near boiling change those readings compared to a batch thats been sitting there cooling down while the sparge finishes.

I'm not concerned with the fact its boiling, I have a ATC Refract so its fine. I'm just curious will there be a difference?

MalFet said:

Keep in mind though that the rate of enzymatic activity in wort decays quite substantially as time goes on. The difference between, say, 90 minutes at mash temps and 120 minutes at mash temps isn't going to be dramatic. It's something, and thus perhaps worth doing if you're really trying to rein in your process, but it's not as though you'll be looking at completely different beers.

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As a completely new question, what time frames would the changes be noticeable to the final outcome of the beer?

Snafu said:

Ok, let me back up. I'm looking at the pros and cons of a mashout. My system is pretty much dialed in and very consistent on OG/FG and hitting targets. One my last batch I opted to not do a mashout in order to gain additional volume for the mash to help control pH. That being said, I was commenting that the #'s didn't really change for me, comparing the readings from prior batches where I did do a mashout. While the whole mash-out/no mash-out question seems to be a matter of personal choice as my #'s didn't change, what I did learn was that the lag time in getting the boil off could change the beers profile as the enzymes continue to break down starches well after the mash was done and the best way to stop that was the mash-out. To "lock" in the profile.

The whole mash/no mash (for me) will depend on the pH I need to control (esp with alot of crystal malts), that being said, and turning focus on the runoff, I currently allow the kettle to fill 100% before I light the burners for the boil. The only reason for this was for me to get a pre-boil gravity reading. If I change my process, to start heating the runoff before the sparge is complete, there is a chance the runoff will be at or very near boiling temp as the fly sparge takes about an hour.

Now to bring in my above mentioned question, since the runoff will already be at or near boiling temp once the sparge is done and I go to take my "pre-boil" gravity reading, how will the fact that I'm at or near boiling change those readings compared to a batch thats been sitting there cooling down while the sparge finishes.

I'm not concerned with the fact its boiling, I have a ATC Refract so its fine. I'm just curious will there be a difference?

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You shouldn't see a significant difference in gravity, and if you do you might want to make sure that you're not cutting your mash short before you've got complete conversion. The difference will not be in gravity, but rather in fermentability. The earlier run-off will presumably be slightly less fermentable than the later wort, though of course it will all mix together and produce something half-way in between. This is related to your next question:

As a completely new question, what time frames would the changes be noticeable to the final outcome of the beer?

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There's an analysis of that question here, though unfortunately it's not based on a ton of data: http://braukaiser.com/wiki/index.php?title=Mash_Time_Dependency_of_Wort_Fermentability

In short, it's not a huge difference: about 4% increase in fermentability over two additional hours. The important thing is not so much being quick or slow, but rather being consistent. This is why I like doing a mashout. Sometimes my kid wants to go to the park, and sometimes four hours will pass between my mash and my boil. Sometimes it won't, and I can't really predict it. If you're more consistent than that, I wouldn't particularly worry about it. If you've got a process in which roughly the same amount of time passes between the end of your mash and the start of your boil (regardless of how long that actually is), you'll get consistent results. From there, you can tweak fermentability to suit your recipes by adjusting mash temperature. That's a much easier parameter to adjust, and it achieves the same ends.

shlap said:

Ive found that when I dont mash out, I get a drier beer with a lower FG than expected.

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Same here as well, Building a Herms setup so I can mash out.

Brew-boy said:

Same here as well, Building a Herms setup so I can mash out.

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If you keep getting lower FG than you expect, maybe you're expectations are the problem

I love Googling a question – inevitably find HBT thread from like 2007 – thread title is exact question I had – a bunch of cats being herded, then someone comes up with the perfect paragraph that clarifies and resolves the question in a way that’s hard to imagine could be better. This is that paragraph.

MalFet said:

In short, it's not a huge difference: about 4% increase in fermentability over two additional hours. The important thing is not so much being quick or slow, but rather being consistent. This is why I like doing a mashout. Sometimes my kid wants to go to the park, and sometimes four hours will pass between my mash and my boil. Sometimes it won't, and I can't really predict it. If you're more consistent than that, I wouldn't particularly worry about it. If you've got a process in which roughly the same amount of time passes between the end of your mash and the start of your boil (regardless of how long that actually is), you'll get consistent results. From there, you can tweak fermentability to suit your recipes by adjusting mash temperature. That's a much easier parameter to adjust, and it achieves the same ends.

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…I love it best when that’s the last post. Everyone just knows. Oh well..

Thanks all. A lot of solid hats around here.

Great thread folks. Thanks!

cats? from Cali..... oh geez, you ain't one dem hippies are ya?

I have a RIMS, so performing a mashout is a piece of cake. I consistently see a couple points increase in Brix after ramping the mash temperature up to about 168F. I know its worthwhile in terms of efficiency, but agree if your brewing methods don't allow for an easy mashout temperature step, forget it.

I too mash out each time due to the ease with my e herms setup. i get better efficiency doing this plus it makes the mash more fluid and my fly sparges are faster.

Snafu said:

cats? from Cali..... oh geez, you ain't one dem hippies are ya?

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Nah, politically I’m somewhere to the right of Attila the Hun.

I did go to a Grateful Dead concert back in college though. Halloween night, in the Oakland coliseum. (F’ yeah. They played “Dark Star, “in space” – apparently that’s really rare – fraternity brothers had ROOMS full of tapes….) I’m used to Slayer concerts. I just walked right up to the front of the stage when it felt like it was about to start, around all those blankets “securing” space. (6’5” – 270 – unconcerned) This little Blonde gal (pissed that I was “cheating”, her head reaching about to my nipples.) She wheeled around and – being taught the secret arts of man killing – grabbed my junk and cranked down as hard as she could, grimacing face to match the extreme effort she was giving. BUT, she grabbed my rod, not my balls, so I just kind of looked at her quizzical. Changed her world, not mine. Invincible at 20-something; but who isn’t. Fun stuff.


Thanks for the rockin thread! You made it happen. (And, yes, your avatar is the best I’ve seen on this site – bar none.)

Mashout is not necessary for home brewers at all. It's necessary in commercial environments because the wort takes much longer to transfer before the boil. With home brewing, after mashing for an hour there isn't much if anything left to convert and if it is its 2 points tops. Don't let anyone tell you differently

Well today I pulled the trigger on all the parts needed for a HERMS. I'm not going full-auto with PIDs and such, just a way to heat the wort in the MLT cooler. Should have everything by Tuesday of next week and installed by the weekend. Even if it takes a little longer, the Ferm chamber won't free up for another two weeks anyway so no big deal. This should make it easier for me to mash out and/or control mash temps without the concerns of adding additional water. Plus, I get to do another DIY project. I'll keep ya posted on the progress.

earwig said:

Mashout is not necessary for home brewers at all. It's necessary in commercial environments because the wort takes much longer to transfer before the boil. With home brewing, after mashing for an hour there isn't much if anything left to convert and if it is its 2 points tops. Don't let anyone tell you differently

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I agree that it isn't necessary at home, but it isn't really necessary at the commercial level either and the vast majority of brewers don't bother... at least not in the sense that they intentionally raise the temp of the mash. A similar effect occurs in that heat is typically applied to the kettle during runoff to assure a rapid ramp up to boiling once the runoff has completed, denaturing enzymes in the process as the kettle temp increases. Further, at a certain point through the sparge, the mash will have gained temp into the denaturing range as a result of continued application of sparge water. Most commercial systems don't have a means of doing a traditional "mashout" in the sense of a direct and intentional increase in mash temperature.

As usual, I have an after thought. When you get right down to it, how effective is a HERMS at raising "step" temperatures? I've never done it so I'm only guessing here, but I would think it could take up to 15 mins to raise the temp from low to mid 150's to 170. Is there a down side to raising the temp in the HLT way above the 170 you need in the MLT to shorten the time it takes to reach your target? When you pour in 200 deg water as an infusion, its immediate. With a HERMS it would be prolonged until its stabilized at your target correct?

So, is the only real reasons (benefits) to a HERMS the ability to control (maintain) mash temp's and wort clarity by constant recirculation?

Snafu said:

As usual, I have an after thought. When you get right down to it, how effective is a HERMS at raising "step" temperatures? I've never done it so I'm only guessing here, but I would think it could take up to 15 mins to raise the temp from low to mid 150's to 170. Is there a down side to raising the temp in the HLT way above the 170 you need in the MLT to shorten the time it takes to reach your target? When you pour in 200 deg water as an infusion, its immediate. With a HERMS it would be prolonged until its stabilized at your target correct?

So, is the only real reasons (benefits) to a HERMS the ability to control (maintain) mash temp's and wort clarity by constant recirculation?

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Yeah, basically. Those are decent benefits, though.

Think of it like this: in an ideal HERMS configuration, the wort leaving your HERMS coil would be exactly the same temperature as the water in your HLT. You would raise the temperature of your wort to the temperature of your HLT in the amount of time it takes to pump your entire volume of wort through the coil. Most systems aren't ideal, of course, so people tend to leave their HLTs a degree or two higher than their target, but the rest of the math still works out the same.

If you heat your HLT to well above 170ºF, the wort coming out of it will also be well above 170ºF. Whether or not that's a bad thing depends on your opinions on whether tannin extraction is something you should worry about or not. Some say yes, others say no.

Under most circumstances, a HERMS will not step your temperatures quite as quickly as a direct fire will. The upside is that you have pretty much zero chance of scorching, and it is easier to keep steady temperatures than with a manual direct fire RIMS system.

Well right now I'm still controlling the flame by hand, no PID controller. So i will be sneaking up on the mash out temp. Is there a down side to adding additional time while the temp rises. Do most just start earlier like at the 45 minute mark?

Snafu said:

Well right now I'm still controlling the flame by hand, no PID controller. So i will be sneaking up on the mash out temp. Is there a down side to adding additional time while the temp rises. Do most just start earlier like at the 45 minute mark?

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It's still easier to control HERMS (in my opinion at least) because you don't have to worry about heat stratification like you do with a direct fire system. You know, in other words, where your temps are so long as you have even a little bit of agitation to move the water around. Plus, if you overshoot you can always just turn off the pump and bring the HLT back down. It's just another layer of distance between the heat and the wort.

I wouldn't necessarily recommend starting your mahout earlier unless you are absolutely sure you are done with conversion by that point. Most starches should have converted by 45 minutes, but the extra 15 minutes just gives you a little bit of insurance in case your crush is off, etc. The extra time certainly isn't bad, except to the extent that it's an extra fifteen minutes that you have to wait. The main thing is just to be consistent in your process.

Awesome, thats the advice I was looking for. Hopefully i'll has this built in time for the next brew. Thanks!

Well HERMS is complete, hello super clear wort & controlled temp mash's.

Took the new HERMS out for a test drive this past weekend, OMG why I didn't do this sooner is beyond me. Made the mash so easy to control. Stabalizing the mash out temp only took about 10 mins and of course the fly sparge was controlled also. I also tried something new, instead of using my CPVC "H" pattern sparge arm do-ma-thingy, I just used a 2' section of silicone hose and just laid that on top of the grain bed. It dropped my efficiency down (like I wanted) close to 80%. I had been getting efficiency #'s a little higher than I wanted cause it was trowing off my ABV. Yeah, I know I could have scaled back the grain bill, but I'd rather keep it where I designed it. Or, like this past weekend, I wanted to make BM's Centennial Blonde and not make changes to the recipe, and have it still come out at 4%. Anyway, got off topic there, HERMS.... if your thinking of doing one, I absolutely suggest going for it. For me, it was the next logical step after gaining control of my fermentation temps with the chamber.

I do think I need to add a second pump to the system, to circulate the HLT water while I circulate the mash. I think it will be more accurate for the temperature reading on my dial thermometer on the HLT. I did give it several stir's while the mash was going on just in case the HLT water started to cool at the top.

Snafu said:

Well HERMS is complete, hello super clear wort & controlled temp mash's.



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I think robby the robot is starting to get excited by your brew sculpture.

Not so much a "sculpture" as it is controlled chaos. :rockin:

i saw a 10% jump in efficiency when i started mashing out. Probably helped with sugar extraction. We didnt change anything else at the time, we had just changed our crush a few batches before but were still in the 78-82% range, now we are hitting 88-92%.