Mixing or Stirring the Mash

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Eric_Duel

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I'm in the design stages of my 3-vessel brewing system. I have my three half-barrel kegs and I am trying to decide between the various techniques.

My question is more specific than the various construction techniques though:

Should the mash be stirred or mixed?

My thinking is that it would be ok as long as no aeration takes place. However, I was reading Dennis Collins' website (the HERMIT brewing system) and he states:

2. Stirring the mash after initial dough-in is bad. If you have a recirculating system, you don't have to stir the mash. In fact, if you stir, you undo 33% of the benefits of a recirculating system. I've tried it both ways, never stirring and stirring about every 15 minutes or so and there wasn't any difference in efficiency or any other measurable parameter. The only thing that happened was that the wort that recirculated for 1 hour was noticeably clearer than wort that recirculated for only 15 minutes. DON'T STIR THE MASH!
Click to expand...

Why?

So I read farther and found articles from BT about building motorized mash mixers.
ex. http://brewingtechniques.com/library/backissues/issue2.6/put.html

What is the reason for not stirring or what should I be careful for/aware of?
 
I have found that you dont need to stir the mash often. I will stir it 2-3 times after i get all the grains in. But only in the first 15 minutes. After that I know Im getting good circulation by watching the wort in the hoses. If you agitate it to much you cal plug your pump, or your false bottom drain with grains. After about 15 minutes I will just circulate the wort to get my temps, then hold them. The grain will compact slightly and form a filter bed. When you sparge in on top of the grain bed you will get an even "rinse" through to the false bottom to help you drain wort to the boil kettle with little or no grains in it. If you continually stir you will will never get the filtering effect.
 
i stir the mash once i get all the grain in to make sure there are no dough balls formed, then i let it set for the saccharification rest . it kind of defeats the purpose of the infusion mash, because if you stir the mash during the rest, it releases the air it needs to "float".
 
Eric_Duel said:
I'm in the design stages of my 3-vessel brewing system. I have my three half-barrel kegs and I am trying to decide between the various techniques.

My question is more specific than the various construction techniques though:

Should the mash be stirred or mixed?

My thinking is that it would be ok as long as no aeration takes place. However, I was reading Dennis Collins' website (the HERMIT brewing system) and he states:



Why?

So I read farther and found articles from BT about building motorized mash mixers.
ex. http://brewingtechniques.com/library/backissues/issue2.6/put.html

What is the reason for not stirring or what should I be careful for/aware of?
Click to expand...

That quote was slightly out of context. I was referring to a recirculating mashing system (RMS) where wort is constantly being recirculated. If you are doing a standard mash, manual mixing is fine and might even boost your efficiency a bit. Mostly, it eliminates temperature gradients in the mash bed that tend to form as the mash progresses. But be careful, every time you open the lid and stir, you will lose some heat.

In a RMS system, no stirring is necessary and should be avoided. The clarity that you achieve after recirculating for an hour is completely undone if you disturb the grain bed.
 
not arguing w/ Dennis, but just another side of it. :~) i quote Gregory Noonan in his book "New Brewing Lager Beer":
"The greatest challenge in an infusion mash is to achieve and maintain a reasonably even saccharification temperature. Unless the mash can be raked during sparging, an infusion mash can't be stirred to disperse temperature evenly, because stirring deaerates the mash, and the lauter will set. Entrained air keeps an infusion mash from settling until late in the sparge cycle.
Temperature variation within the mash, then, is almost inevitable, and within limits is considered acceptable. So long as variations do not exceed +/- 2 degrees F of the target saccharification rest temperature, attenuation consistency will be acceptable".
Greg Noonan is owner and brewmaster at the Vermont Pub and Brewery, founder of the Seven Barrell Brewery, author of Scotch Ale inthe Classic Beer Style series, and a decoction mashing specialist. this is a real good book for the nut's and bolts of brewing.
 
DeRoux's Broux said:
not arguing w/ Dennis, but just another side of it. :~) i quote Gregory Noonan in his book "New Brewing Lager Beer":
"The greatest challenge in an infusion mash is to achieve and maintain a reasonably even saccharification temperature. Unless the mash can be raked during sparging, an infusion mash can't be stirred to disperse temperature evenly, because stirring deaerates the mash, and the lauter will set. Entrained air keeps an infusion mash from settling until late in the sparge cycle.
Temperature variation within the mash, then, is almost inevitable, and within limits is considered acceptable. So long as variations do not exceed +/- 2 degrees F of the target saccharification rest temperature, attenuation consistency will be acceptable".
Greg Noonan is owner and brewmaster at the Vermont Pub and Brewery, founder of the Seven Barrell Brewery, author of Scotch Ale inthe Classic Beer Style series, and a decoction mashing specialist. this is a real good book for the nut's and bolts of brewing.
Click to expand...
Interesting. This doesn't jive with my experience in a RMS. With constant recirculation, I would assume my mash would deaerate as he describes, but I don't have a problem with the mash sticking. Perhaps this an issue of scale, where a large mash with a deep grain bed might be prone to sticking if deaearated, such as the difference between a commercial batch and a homebrew batch? Is he basically saying that you shouldn't stir the mash?
 
It seems like as long as the wort is returned to the mash below the top of the mash you wouldn't have any oxygen at all in the system (at least after the initial purge), hence no deaeration. But I've never even seen a recirculating system in person.
 
tnlandsailor said:
Perhaps this an issue of scale, where a large mash with a deep grain bed might be prone to sticking if deaearated, such as the difference between a commercial batch and a homebrew batch? Is he basically saying that you shouldn't stir the mash?
Click to expand...
that's what i got out of it (not to stir the mash). the book is geared towards small scale brewing, as are the recipes. and i think he means once you get the saccharification temp your looking for, to basicaly let it ride for the rest.

like i sid, not arguing, just my experience and what i've read about infusion brewing. this guy's pretty sharp, and i dig his books. ;)
 
Thanks for the replies guys.

And Dennis, thanks for the clarification. Though it wasn't expressed, I didn't mean to say your statement applied to everything.

I have a better idea about the methods and when each might be used. I do plan on building a two-tiered system equipped with a pump, so it would make sense to me to have a recirculating system. I wasn't quite up on the entrained air in the mash. That's a helpful point.
 
Nothing like reviving a 10 year old thread!

Did anyone consider a potential issue with not stirring around the question of grain expansion? It seems to me if nothing is stirred after doughing-in until sparging then during this time the malts will (broadly speaking) first settle and then expand as the grains swell. If the proportions of the tun mean a relatively taller bed, you could have a lot of pressure at the bottom of the bed to lift up the rest upwards, which could lead to a much more compacted lower bed. If the mash is stirred at least once after the majority of expansion this is avoided.

I'd guess the narrower the tun the more resistance this upward push is going to
meet, so this may be an issue for smaller/taller tuns of the ~22L cool-box variety.

Does that seem fairly reasonable?
 

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