How important is mash temperature, *really*?

[chipwitch]

Yesterday, I brewed my second true AG. I never liked the idea of using plastic for the mash tun. So, I bought a 15 gallon aluminum pot. I realize that pot is just about the worst possible choice for 5 gallon batches, however, it's given me a unique understanding of the physics of heat/heat loss, etc.

First, the rig. It's a nice heavy aluminum pot about 16" around. I have a 12" domed false bottom and a 1/2" SS valve mounted to the side via SS tubing. The ID of the tubing is the limiting factor, 5/16" iirc. There is an aluminum lid.

The first AG I did with this rig was with a crappy (read: useless) science lab mercury thermometer. I tossed it and bought a thermapen (love it). It is so accurate and quick, you have full confidence in your readings.

Here's what I did to mash. Since aluminum transfers heat so quickly, you need a substantial insulation layer or you need to add heat. I chose the latter as previous experiments with reflectix were a fail. The method was what I'll call GFRIMS (Gravity Fed RIMS). By setting the flame on the lowest setting and controlling flow with the valve, I could heat the mash continuously to account for loss, effectively controlling the temperature. A super fast read thermometer like the thermapen makes this possible. Collecting the wort into a SS pitcher, it could be easily returned to the top of the mash. I held the temperature between 154F and 156F.

For kicks, I tested the mash from above, rather than the stream out of the spigot. What I found is that the mash was 148F. I expected there to be some stratification and the heat would mostly be absorbed beneath the grain bed, but I didn't expect ab 8 degree differential.

So, that got me thinking about all the talk about the temp you mash at. People talk about mashing to the degree F, when from what I see, it's virtually impossible to keep a uniform temperature throughout. Here is where I imagine the plastic cooler excels, but I'm betting there is still some stratified temperature differential.

So, my question is, "Is the importance of mash temperature, to the 1.0 degree Fahrenheit, overstated?

<edit:> I should mention, I got great conversion. I used braukaiser's spreadsheet for simulating batch sparging. I exceeded the estimated SG's at every step (3 sparge) by about a point.

 

[atom]

i don't find a few degrees to matter much...

http://brulosophy.com/2015/10/12/the-mash-high-vs-low-temperature-exbeeriment-results/

 

[GrogNerd]

to the degree of "you won't make beer unless" than, yes... very overstated

to the degree of how much fermentability do you want in your wort or how accurately you want to predict your FG... maybe

to the degree of how badly you want to repeat that same brew next time, no.... not in the least overstated

this hobby is all about degrees of tolerance and how much you're willing to accept. an ounce of grain here, a fraction of an ounce of hops there, a degree in your mash, a minute of boil time, doesn't make a whole lot of difference if you don't want it to

 

[b-boy]

I'm sure it's important if I'm trying to reproduce a beer that tastes exactly the same every batch. Professionals probably rely on exact mash temperatures when they brew.

It's also critical to avoid denaturing enzymes (if it's way too high).

From a home brew perspective, I don't sweat 1-2 degrees. There are so many variables that will impact my final product, that I doubt I'll ever be able to reproduce an exact copy of a beer I've brewed before. I may get close though.

That being said, I'd rather be a little higher, and let the temperature drop over my mash time than go in lower than my target.

 

[iijakii]

Not too drastic to me. My old HERMS rig and my new basic BIAB with significant temp loss both produce the same results. My FGs are pretty much always where predicted.

 

[blizz81]

So, that got me thinking about all the talk about the temp you mash at. People talk about mashing to the degree F, when from what I see, it's virtually impossible to keep a uniform temperature throughout.

In my insulated keggle RIMS, I can poke around to my heart's content in the mash after a little bit and the temp varies at maximum 0.5* according to my Thermoworks lengthy (12" or 18", I forget) probe. That's uniform enough for me.


As to how important it is, really? Given the gradual nature of alpha and beta amylase both in terms of denaturing and activity, I'd say some stratification to a certain X delta of degrees is going to impact you fairly minimally. Now, if you had my roommate's old almost-$300 "made for homebrewing" MiniBrew mash tun that lost 10-15 degrees over the course of an hour of mashing, it made quite a bit of difference. We had to take pretty extreme grist measures to keep beers of all styles from fermenting out below about 1.008 .

 

[chipwitch]

Not too drastic to me. My old HERMS rig and my new basic BIAB with significant temp loss both produce the same results. My FGs are pretty much always where predicted.

I'm assuming you're saying the temperatures between the two rigs varies considerably, but you can detect no difference? Mouth feel either?

 

[iijakii]

That's been my experiences, yes. I don't worry about to-the-degree accuracy anymore.

 

[chipwitch]

In my insulated keggle RIMS, I can poke around to my heart's content in the mash after a little bit and the temp varies at maximum 0.5* according to my Thermoworks lengthy (12" or 18", I forget) probe. That's uniform enough for me.


As to how important it is, really? Given the gradual nature of alpha and beta amylase both in terms of denaturing and activity, I'd say some stratification to a certain X delta of degrees is going to impact you fairly minimally. Now, if you had my roommate's old almost-$300 "made for homebrewing" MiniBrew mash tun that lost 10-15 degrees over the course of an hour of mashing, it made quite a bit of difference. We had to take pretty extreme grist measures to keep beers of all styles from fermenting out below about 1.008 .

Sounds like an aluminum pot? Mine is about the same 15 degrees an hour... easily. I would expect a good RIMS with plenty of flow would be about as uniform as you could get. .5 degrees is respectable.

I've been asked by members here trying to help me troubleshoot batches ask me my mash temp. I just didn't realize how arbitrary that question is as I've seen others talk similarly. Like, "Oh, there's the problem, you mashed at 152 instead of 155. First, even thermapen is only accurate to within +/- 1 degree, so two members with the exact same rigs could be off by two degrees. I've learned the lesson that you must keep your rig constant, use the same thermometer, at the same location in order to get a reading. If you do that, then you may expect similar batches from batch to batch. But to ask someone on a forum what temp they mash at can only be vaguely useful. I'm not faulting members who've done that... I'm only saying that, from that, I got the distinct impression that maintaining a uniform temperature within one degree was expected. After this last batch, I realize how silly THAT notion was

 

[chipwitch]

Thanks guys, all your responses helped clear me up on that.

Cheers!

 

[blizz81]

Sounds like an aluminum pot? Mine is about the same 15 degrees an hour... easily.

It was actually a GOTT-style plastic thing. What a fail for the price. It looks like a cooler, yet is a solid piece of plastic - not jacketed like a cooler.

http://minibrew.com/product/deluxe-mash-lauter-tun/

I've been asked by members here trying to help me troubleshoot batches ask me my mash temp. I just didn't realize how arbitrary that question is as I've seen others talk similarly. Like, "Oh, there's the problem, you mashed at 152 instead of 155. First, even thermapen is only accurate to within +/- 1 degree, so two members with the exact same rigs could be off by two degrees. I've learned the lesson that you must keep your rig constant, use the same thermometer, at the same location in order to get a reading. If you do that, then you may expect similar batches from batch to batch. But to ask someone on a forum what temp they mash at can only be vaguely useful. I'm not faulting members who've done that... I'm only saying that, from that, I got the distinct impression that maintaining a uniform temperature within one degree was expected. After this last batch, I realize how silly THAT notion was

Even that, I think more brewers on here than not are probably using a combination of the following: cheap-ish thermometer, static thermometer / measuring one place in the mash, thermometer not quite calibrated for mash temp ranges. Kind of lending more to the credence that it may not be worth worrying much over.


I got a little carried away with it (building the RIMS mash tun, giving Thermoworks like $120 of my hard-earned money) only as a result of losing so much temp and fighting to brew sweeter beers to style. If I'd have had a cooler, I'd probably still be happily using it. It was a fun build though, and it's nice to have a good thermometer / good probes.

 

[chipwitch]

It was actually a GOTT-style plastic thing. What a fail for the price. It looks like a cooler, yet is a solid piece of plastic - not jacketed like a cooler.

http://minibrew.com/product/deluxe-mash-lauter-tun/





Even that, I think more brewers on here than not are probably using a combination of the following: cheap-ish thermometer, static thermometer / measuring one place in the mash, thermometer not quite calibrated for mash temp ranges. Kind of lending more to the credence that it may not be worth worrying much over.


I got a little carried away with it (building the RIMS mash tun, giving Thermoworks like $120 of my hard-earned money) only as a result of losing so much temp and fighting to brew sweeter beers to style. If I'd have had a cooler, I'd probably still be happily using it. It was a fun build though, and it's nice to have a good thermometer / good probes.

The story of going to RIMS and back again to BIAB sounds familiar. Did you write a blog about it?

 

[masaba]

It makes a difference in gravities, but does it actually matter as far as taste...maybe not.

http://brulosophy.com/2015/10/12/the-mash-high-vs-low-temperature-exbeeriment-results/

 

[tsl346]

Y
For kicks, I tested the mash from above, rather than the stream out of the spigot. What I found is that the mash was 148F. I expected there to be some stratification and the heat would mostly be absorbed beneath the grain bed, but I didn't expect ab 8 degree differential.

So, that got me thinking about all the talk about the temp you mash at. People talk about mashing to the degree F, when from what I see, it's virtually impossible to keep a uniform temperature throughout. Here is where I imagine the plastic cooler excels, but I'm betting there is still some stratified temperature differential.

So, my question is, "Is the importance of mash temperature, to the 1.0 degree Fahrenheit, overstated?

What I normally see if I have a temperature gradient at all is the water is normally hotter than the grains by about 3-4 degrees. I stir stir stir for a couple of minutes and after 5-10 minutes of mash it equalizes. This is in a cooler, though, not an aluminum pot. Definitely where the cooler excels.

 

[Pappers_]

It seems people are talking about two different things here: does mash temp matter and does a difference of a degree matter? Two very different questions, in my opinion.

Mash temps matter a lot. But its not a matter of a degree more or less. In my brewing, if I'm aiming for a very light, crisp, dry, easy to drink beer and my mash ends up at 154F, well, I won't get what I was aiming for. Also, if I want a big thick beer and end up at 152F, I'm going to be disappointed as well. Maybe its helpful to think of it in ranges - low (148-150), medium (152-154) and high (156-158). If I'm aiming for one of the ranges and end up in another, I notice it in the finished the beer.

 

[ericbw]

No one seems to be saying 1-2 degrees matter, but maybe 2-3? And 3-5?

I have the same concern, not even stratification. Stick the thermometer in 5 different spots on top of the mash, and you get 5 different temps.

I aim for the average. And try to get close.

Like pappers, I think of low or high. (

 

[cantrell00]

Only at the extremes relative to style does it matter in my opinion.

You generally don't want to mash a DIPA @ 155 or a porter @ 147 as an extreme example.

 

[Jhu1321]

I use aluminum and I just stir the mash every 15 minutes or so to even out the temperature. I also use a layer of reflectix and cut around the thermometer and spigot and added velcro to assure a snug fit. I'm usually within a degree or two of where I want to be but If I fall lower I'll fire up the burner on low for 5 minutes (no more than that) and stir afterwards. The wort transfers the heat really slowly so it's easy to go too far.....

 

[blizz81]

The story of going to RIMS and back again to BIAB sounds familiar. Did you write a blog about it?

I'm still on RIMS / never did BIAB. Maybe iijakii ?

 

[charliehorse]

It seems that we're going to have to call on SCIENCE! to answer this question. Inside each kernel of barley (and other grains to a lessor extent) is an enzyme called Amylase. As homebrewers, we know this and we accept it. It actually goes a little deeper than that. Amylase is actually more than one enzyme. Think of a carbohydrate molecule as something similar to a mop. There are Alpha Amylase and Beta Amylase, which are activated at 154-162 and 131-150 (respectively) degrees Fahrenheit. They have similar sounding names, but do different things. Beta Amylase produces Maltose, which is a disaccharide (2 sugar molecules), and is easily eaten by yeast (think of this as cutting each string into shorter pieces). Alpha Amylase breaks apart where the long strands are joins (think of this as cutting the part of the mop head that is attached to the handle). This is why you see folks using a step mash.

In general, to get the most fermentables out of your grain, you'll want to keep your mash temperature between 148 and 152 (and there is a noticeable difference between the two extremes). Remember, even if you're batch sparging in a cooler like a lot of use do, you can start with your mash temperature in the 145 range and add hotter water to increase the temperature. Once you get above an enzyme's happy zone (by too much), those enzymes will start to die, so it's far better to start at the lower end of the scale and work your way up.

 

[blizz81]

It seems that we're going to have to call on SCIENCE! to answer this question. Inside each kernel of barley (and other grains to a lessor extent) is an enzyme called Amylase. As homebrewers, we know this and we accept it. It actually goes a little deeper than that. Amylase is actually more than one enzyme. Think of a carbohydrate molecule as something similar to a mop. There are Alpha Amylase and Beta Amylase, which are activated at 154-162 and 131-150 (respectively) degrees Fahrenheit. They have similar sounding names, but do different things. Beta Amylase produces Maltose, which is a disaccharide (2 sugar molecules), and is easily eaten by yeast (think of this as cutting each string into shorter pieces). Alpha Amylase breaks apart where the long strands are joins (think of this as cutting the part of the mop head that is attached to the handle). This is why you see folks using a step mash.

In general, to get the most fermentables out of your grain, you'll want to keep your mash temperature between 148 and 152 (and there is a noticeable difference between the two extremes).

I think that's kind of the argument here. That there is or isn't a "noticeable" difference between the two extremes, if we're calling "extremes" 148 and 152, and what is "noticeable".


Sidebar: "get the most fermentables out of your grain" - really if you wanted to get the "most fermentables" out of your grain (presumably most fermentables = least non-fermentable sugars), you could / would go lower to the land where alpha is nil and beta is still working. You can get extraction for a ways lower than 148, though it might take longer, and then you potentially have a super-fermentable wort! Of course, other things are in play here - grist, yeast potential, yeast health / happiness, etc.


General comment: our old friend the Palmer graph:

 

[Rev2010]

Obviously we all know about the fermentability of the wort and how temperature affects it. Will a degree or so matter, not drastically but a few degrees will, especially if you want exact repeatability. I wanted to address one thing here though since you mentioned temp loss. Keep in mind a number of experiments have shown that mash conversion is mostly complete in a short span of time, say around 15 minutes, so a temperature drift of a few degrees over an hour long mash might not have such a noticeable impact since most conversion has already taken place.


Rev.

 

[charliehorse]

Will a degree or so matter, not drastically but a few degrees will, especially if you want exact repeatability.Rev.

The answer to that is the same as they answer to the question "how long is a piece of string?" It depends. It depends on where the temperature is before the drift. Think of it like being in a boat. If my motor quits and I start to drift, how much danger am I in? That depends on where you are when you start to drift. If you're 20 feet from a rock jetty, you're in a lot more danger than if you're 10 miles from the nearest obstacle.

Likewise, if your temperature is 150 and you drift a couple of degrees, the world isn't coming to an end but if you start at 145 and you loose 15 degrees, you might not like the result.

 

[Rev2010]

Likewise, if your temperature is 150 and you drift a couple of degrees, the world isn't coming to an end but if you start at 145 and you loose 15 degrees, you might not like the result.

Not sure what your analogies have to do with my post that you quoted. Of course how much a drift matters, that's fairly common sense I'd say. Dropping 15 degrees would be tremendous. But as I mentioned though time also matters. Is a drop of 5 degrees over an hour going to matter tremendously? Probably not all that much if conversion does indeed complete mostly in the first 10-15 minutes as some recent tests have shown. 5 degrees, if the decline is steady, would equate to a 1 degree drop over 12 minutes. So for all intents and purposes let round up and say that would equate to a 1.5 degree drop during the majority, or all, of the mash conversion - ie. not uber dramatic.

Regardless, I think controlling mash temp is important and that yes it obviously does have an affect. We all know this already though so I don't see any need to elaborate further on that. But the point is mainly - if you want to reproduce the beer exactly it's best to hit and maintain temps. But, if you drift a degree or two it's not going to make a suddenly strikingly different beer.


Rev.

 

[chipwitch]

I use aluminum and I just stir the mash every 15 minutes or so to even out the temperature. I also use a layer of reflectix and cut around the thermometer and spigot and added velcro to assure a snug fit. I'm usually within a degree or two of where I want to be but If I fall lower I'll fire up the burner on low for 5 minutes (no more than that) and stir afterwards. The wort transfers the heat really slowly so it's easy to go too far.....

Does your mash tun have a false bottom?

 

[chipwitch]

It seems that we're going to have to call on SCIENCE! to answer this question. Inside each kernel of barley (and other grains to a lessor extent) is an enzyme called Amylase. As homebrewers, we know this and we accept it. It actually goes a little deeper than that. Amylase is actually more than one enzyme. Think of a carbohydrate molecule as something similar to a mop. There are Alpha Amylase and Beta Amylase, which are activated at 154-162 and 131-150 (respectively) degrees Fahrenheit. They have similar sounding names, but do different things. Beta Amylase produces Maltose, which is a disaccharide (2 sugar molecules), and is easily eaten by yeast (think of this as cutting each string into shorter pieces). Alpha Amylase breaks apart where the long strands are joins (think of this as cutting the part of the mop head that is attached to the handle). This is why you see folks using a step mash.

In general, to get the most fermentables out of your grain, you'll want to keep your mash temperature between 148 and 152 (and there is a noticeable difference between the two extremes). Remember, even if you're batch sparging in a cooler like a lot of use do, you can start with your mash temperature in the 145 range and add hotter water to increase the temperature. Once you get above an enzyme's happy zone (by too much), those enzymes will start to die, so it's far better to start at the lower end of the scale and work your way up.

I get the concept of alpha and beta amylase having optimum temperatures. Kudos to science. But it seems to me, that "getting the most" out of them and maybe even ten degrees off means only a slight hit in efficiency (converting starch in x minutes). Denaturing is an obvious exception to my point, but even at denaturing temps, it will take some amount of time to denature the amylases and I've seen no one specify that time using science. Maybe 15 minutes before you end up with porridge?

I'm not suggesting the science is wrong. I'm just saying based on the realization that even the most precise thermometers (below NASA grade) are inaccurate by as much as 20 percent of the accepted mash range. As if that weren't enough, mash's susceptibility of mash to inconsistent temperature gradients compounds that problem further. I initially had temp readings of 168 in my last mash at the beginning. Being below the false bottom, I could not stir it away. I had to drain some. It took almost 5 minutes to get the temp down to my target. Still, I got great conversion.

 

[chipwitch]

I think that's kind of the argument here. That there is or isn't a "noticeable" difference between the two extremes, if we're calling "extremes" 148 and 152, and what is "noticeable".


Sidebar: "get the most fermentables out of your grain" - really if you wanted to get the "most fermentables" out of your grain (presumably most fermentables = least non-fermentable sugars), you could / would go lower to the land where alpha is nil and beta is still working. You can get extraction for a ways lower than 148, though it might take longer, and then you potentially have a super-fermentable wort! Of course, other things are in play here - grist, yeast potential, yeast health / happiness, etc.


General comment: our old friend the Palmer graph:

Thanks for the chart. I've never seen it before.

Just to be clear, I should rephrase my op... I'm not arguing the science. The properties of the amylases are well documented.

I am arguing the importance of the + readings + we get and discuss at length on this and other sites. When someone suggests that the 152F is the cause of a particular problem as if to disregard the far more difficult task of measuring the mash accurately (hot spots, thermometer/method error etc). The potential for reading error is great for most home brewers. Even larger mash tuns of commercial brewers would be even MORE difficult in regards to hot spots. I'm guessing they all use a RIMS or HERMS? Continuous heavy recirculation or stirring I would think is a MUST to avoid hot spots and ensure consistency?

Here's another example... say someone gives me a recipe and that recipe calls for mashing at 156. If I try to make that recipe with MY rig, the mash temperature might as well be disregarded given the difference in systems. My system might need to be 160 to duplicate that recipe. It makes temperature arbitrary, to some extent, in that situation. Given that few of us have temperatures consistent throughout the mash to within a half degree F, each amylase globule is exposed to a range of temperatures. It may be at 145 for a while, then at 150... or even 158 or 165. At some point that globule will work really well, others not so well. Some globules may become denatured. That's okay, others will pick up the slack and convert the starch.

Maybe I'm all wet, but that's how I see it. The actual reading gets too much importance, it seems

 

[ericbw]

It seems that we're going to have to call on SCIENCE! to answer this question. Inside each kernel of barley (and other grains to a lessor extent) is an enzyme called Amylase. As homebrewers, we know this and we accept it. It actually goes a little deeper than that. Amylase is actually more than one enzyme. Think of a carbohydrate molecule as something similar to a mop. There are Alpha Amylase and Beta Amylase, which are activated at 154-162 and 131-150 (respectively) degrees Fahrenheit. They have similar sounding names, but do different things. Beta Amylase produces Maltose, which is a disaccharide (2 sugar molecules), and is easily eaten by yeast (think of this as cutting each string into shorter pieces). Alpha Amylase breaks apart where the long strands are joins (think of this as cutting the part of the mop head that is attached to the handle). This is why you see folks using a step mash.



In general, to get the most fermentables out of your grain, you'll want to keep your mash temperature between 148 and 152 (and there is a noticeable difference between the two extremes). Remember, even if you're batch sparging in a cooler like a lot of use do, you can start with your mash temperature in the 145 range and add hotter water to increase the temperature. Once you get above an enzyme's happy zone (by too much), those enzymes will start to die, so it's far better to start at the lower end of the scale and work your way up.

If these enzymes are activated at 154-162 and 131-150, what happens if you mash at 152?

I'm curious how you quantify noticeable difference between the extremes of 148 and 152.

 

[Rev2010]

Here's another example... say someone gives me a recipe and that recipe calls for mashing at 156. If I try to make that recipe with MY rig, the mash temperature might as well be disregarded given the difference in systems. My system might need to be 160 to duplicate that recipe.

In which instance would your system ever require a difference in mashing temp? Temperature is temperature, I can't see in any way why your system would need to mash the beer at 160 instead of 156. That doesn't make much sense. If you're referring to something like temperature drop then that's something you should be fixing and not trying to compensate for by starting with higher mash temps.


Rev.

 

[chipwitch]

Many situations. Depends on the accuracy of your thermometer and placement. It was impractical for me to measure mine anywhere but coming out of the spigot. Heat added at the bottom. But the mash above the false bottom might average 154. The point is, if you ask someone what they mash at, you have to make a whole lot of assumptions to consider it accurate.

 

[Rev2010]

Many situations. Depends on the accuracy of your thermometer and placement. It was impractical for me to measure mine anywhere but coming out of the spigot. Heat added at the bottom. But the mash above the false bottom might average 154. The point is, if you ask someone what they mash at, you have to make a whole lot of assumptions to consider it accurate.

Yeah, but the vast majority of people seem to measure the mash temp using a thermometer stuck into the top of the mash, as do I. I'd imagine the temperature variation would be within a certain degree of variance that isn't so wildly dramatic across similar cooler systems. I better see what you are saying now, but it still leaves a lot of testing and variance compensation as opposed to just speculating one needs to start 4 degrees higher. Again, I don't think a degree or two will make a world of difference, not at all, but several degrees will. I think the more important point is still to make one's mash tun setup stable to hit and maintain Temps. If you don't do that you'll take ages trying to figure out compensation - ie. start and end temp points.


Rev.