Acceptable drop in mash temp?

[petrolSpice]

My first question is, what is an acceptable drop in mash temp? Without adding heat I'd expect to lose some heat, but how much can be lost before I should think about heating it back up?

And for the second question, lets use this scenario... Let's say the desired mash temp is 152F. And then let's assume that without adding heat I will lose 4F degrees over 60 minutes. Should I aim to start the mash at 152F (end at 148F), end the mash at 152F (start at 156F), or average at 152F (start at 154F, end at 150F)?

I will be mashing in my 44qt kettle around which I will wrap some of that Reflectix insulation. I use a propane camp stove for heat and I am weary of trying to use it to maintain a constant mash temp, it may not operate at that low of a setting. Instead I'm considering getting a hot plate hooked to an STC-1000 to help maintain the mash temp.

Thanks!

 

[RM-MN]

This is a complex question as there are several variables. For starters, how well is your grain milled? Coarse milled grains take much longer to complete conversion that finely milled grains because it takes longer to get the center of the particles wet. Until they get wet through your temperature determines how fermentable your wort will become and if you lose heat during this time, your wort becomes more fermentable. Very finely milled grain can comvert in less than 3 minutes according to experimentation I have done.

The second part of this is mash pH because the enzymes work at different rates with different pH readings. I haven't experimented with this.

Assuming that you milled your grains fine and that your mash pH was in the acceptable range, you could be done with mashing in 20 to 30 minutes which leaves little time for the mash to cool, especially with BIAB with it higher water to grain ratio. Indoors where I don't have to deal with cold wind, and doing a very short mash (10 minutes) I lose about 0.3 degrees F. With that, I don't even think of adding heat. I've tried adding heat before I learned about the short mash but unless I was stirring constantly and vigorously, I got hot spots in the mash.

 

[wilserbrewer]

This is a complex question as there are several variables.

Exclamation point!

I tend to see a 3-4 degree drop over a 60 minute mash, and will try and anticipate that by mashing a couple degrees high and letting it fall. I would not attempt to start a mash at 149, but would rather start a mash at 152 - 156, so even with the anticipated temp loss I am still at a reasonable mash temp.

I guess I just mash within a temperature range, rather than a specific temperature. I also feel that it is not all that critical. Somewhere I remember reading a post that mash temp may not be all that influential on wort characteristics.

FWIW, I have also done overnight long duration mashes in a cooler where the mash temp was in the 130's the following morning, and all worked out fine in the finished product.

Maybe the best and simplest advice would be to RDWHAHB cheers!

 

[dobe12]

Somewhere I remember reading a post that mash temp may not be all that influential on wort characteristics.

This goes against everything I've ever read, heard, seen, experienced, etc with all grain brewing. Mash temp most certainly is influential on wort characteristics. More specifically the fermentability of the wort.

I must have missed what your point/meaning was here.

 

[RM-MN]

Exclamation point!

I tend to see a 3-4 degree drop over a 60 minute mash, and will try and anticipate that by mashing a couple degrees high and letting it fall. I would not attempt to start a mash at 149, but would rather start a mash at 152 - 156, so even with the anticipated temp loss I am still at a reasonable mash temp.

I guess I just mash within a temperature range, rather than a specific temperature. I also feel that it is not all that critical. Somewhere I remember reading a post that mash temp may not be all that influential on wort characteristics.

FWIW, I have also done overnight long duration mashes in a cooler where the mash temp was in the 130's the following morning, and all worked out fine in the finished product.

Maybe the best and simplest advice would be to RDWHAHB cheers!

I wonder if that works out because all the conversion is done and the enzymes already denatured before you went to sleep? If the enzymes were still working you should have ended up with a super fermentable wort as the beta amylase kept shortening up the long chain sugars.

 

[dobe12]

To the OP, I use reflective insulation around my mash pot (BIAB'er) and you won't lose much heat over an hour. On a cold winter day, I may lose 3-4 degrees over an hour. If you start at the correct mash temp or maybe a degree above, you'll be fine. In the summer, I've seen temps anywhere from not losing a degree to losing maybe 1-2 degrees over an hour. Again, nothing at all to worry about.

I routinely mash to the exact temp I'm trying to hit or at the most I may shoot for 1 degree over. A 1 - 4 degree drop over an hour is nothing to worry about. You're mash will still be in the expected range for the majority time that conversion is actually happening.

RDWHAHB!

 

[wilserbrewer]

I wonder if that works out because all the conversion is done and the enzymes already denatured before you went to sleep? If the enzymes were still working you should have ended up with a super fermentable wort as the beta amylase kept shortening up the long chain sugars.

Maybe, maybe, maybe, I don't really know. Perhaps conversion continued and the crystal malt and other non fermentables were enough to balance the beer???

I don't really have any data besides the beer was consumed and enjoyed...

 

[helibrewer]

"Conversion complete" is specific to temperature (assuming pH is constant). At a constant 156F you will get to a point where conversion activity has progressed as far as it can given the environment. If you drop the temperature to 150, additional conversion can/will occur as the temperature becomes optimized for the beta amylase. By additional conversion I mean the breaking of the alpha amylase products into maltose and maltotiose.

So you really cannot say that conversion is "complete" at say 156 then let the mash cool and assume that no further conversion is going to take place...unless you mash out at a high enough temperature to denature the enzymes first.

 

[stpug]

I like to keep my mash within a 2 degree variance if possible (±1°F). This is easily accomplished by reserving 1 quart of your strike water, heating it to boiling, and adding it at the halfway point - plus you get to give your mash a stir and check temp at midway. I ended up settling on this method due to significant temperature drops during the mash (4-8 degrees) which was resulting in overly dry beers (and overly bitter beers due to dryness). FWIW

 

[RM-MN]

I found this article in "Brew Your Own" that seems to answer the question I posed to Wilserbrewer about whether further amylase action occurred overnight. https://byo.com/porter/item/1543-understanding-enzymes-homebrew-science

This section seems to answer that question with a resounding "NO".

Beta amylase is active between 131° and 149° F. But like all enzymes, its activity reaches a peak, declines, and then drops precipitously as temperature increases. The rate is also dependent on the amount of enzyme present. It takes time for all of the enzyme to be destroyed, but what is still intact works very quickly. So as the mash temperature approaches 149° F, beta amylase is operating at its fastest rate but it is also being denatured.

This may seem trivial, but at these higher temperatures the denaturation is so rapid that the enzyme is mostly gone in less than 5 minutes. Also, in a homebrewer’s mash tun, where the grain may be poured into very hot water, the exposure to very high heat for the few seconds before the mixture becomes homogenous may work to destroy the fragile enzymes.

 

[ericbw]

This is a complex question as there are several variables. For starters, how well is your grain milled? Coarse milled grains take much longer to complete conversion that finely milled grains because it takes longer to get the center of the particles wet. Until they get wet through your temperature determines how fermentable your wort will become and if you lose heat during this time, your wort becomes more fermentable. Very finely milled grain can comvert in less than 3 minutes according to experimentation I have done.

The second part of this is mash pH because the enzymes work at different rates with different pH readings. I haven't experimented with this.

Assuming that you milled your grains fine and that your mash pH was in the acceptable range, you could be done with mashing in 20 to 30 minutes which leaves little time for the mash to cool, especially with BIAB with it higher water to grain ratio. Indoors where I don't have to deal with cold wind, and doing a very short mash (10 minutes) I lose about 0.3 degrees F. With that, I don't even think of adding heat. I've tried adding heat before I learned about the short mash but unless I was stirring constantly and vigorously, I got hot spots in the mash.

Every time you post, your mash times get shorter. By next week, you'll be posting that you get full conversion before the grain is even milled; you bottle during the mash; and by the time the boil is done, you're already drinking the *next* batch.

 

[ericbw]

"Conversion complete" is specific to temperature (assuming pH is constant). At a constant 156F you will get to a point where conversion activity has progressed as far as it can given the environment. If you drop the temperature to 150, additional conversion can/will occur as the temperature becomes optimized for the beta amylase. By additional conversion I mean the breaking of the alpha amylase products into maltose and maltotiose.

So you really cannot say that conversion is "complete" at say 156 then let the mash cool and assume that no further conversion is going to take place...unless you mash out at a high enough temperature to denature the enzymes first.

Wouldn't one set of enzymes be denatured at 156, so if you drop to 150, they are already denatured and not active?

 

[dobe12]

Wouldn't one set of enzymes be denatured at 156, so if you drop to 150, they are already denatured and not active?

I was under this impression too. So you can mash in the upper 140's to get highly fermentable sugars then raise the temp to the mid/upper 150's to get less fermentable sugars and add body.

BUT, this doesn't work in reverse. You can't start in the upper 150's, hold for bit, then drop down to the upper 140's to get a more ferementable wort. Once you hold in the upper 150's you are denaturing the enzymes needed lower temp conversion.

 

[RM-MN]

Every time you post, your mash times get shorter. By next week, you'll be posting that you get full conversion before the grain is even milled; you bottle during the mash; and by the time the boil is done, you're already drinking the *next* batch.

And you're still mashing for 90 minutes because that's what you've always done?:cross:

 

[ericbw]

And you're still mashing for 90 minutes because that's what you've always done?:cross:

Mashing is so old school. I go straight from the field to the fermenter.

I'm not saying you can't get conversion in less than the "normal" mash times. I'm saying that your posts often include shorter and shorter and shorter mash times. Here you're saying conversion is complete in 3 minutes.

 

[Ilan34]

Every time you post, your mash times get shorter. By next week, you'll be posting that you get full conversion before the grain is even milled; you bottle during the mash; and by the time the boil is done, you're already drinking the *next* batch.

I chuckled.

Sent from my SCH-I545 using Home Brew mobile app

 

[ericbw]

I chuckled.

Sent from my SCH-I545 using Home Brew mobile app

Finally!

 

[RM-MN]

Mashing is so old school. I go straight from the field to the fermenter.

I'm not saying you can't get conversion in less than the "normal" mash times. I'm saying that your posts often include shorter and shorter and shorter mash times. Here you're saying conversion is complete in 3 minutes.

That's what my tests with iodine are showing. If you read the excerpt from BYO magazine, at temperatures over 149, beta amylase is denatured in less than 5 minutes. Why would I mash for longer times than that if all my fermentables are already created.

Longer mash times are needed when your grain particles are larger because the amylase enzyme do not become active and are not denatured (apparently, since pale malt is kilned at about 210 degrees) until they become wet. With the crush you have to have in a conventional mash tun due to the lack of other filtering, you need the larger particles. With BIAB you don't because you aren't depending on the grain to form its own filter but use a fine mesh bag to keep the grain particles out of the boiling kettle.

 

[stpug]

From what I'm reading, hearing, gathering, the iodine test is not an accurate way of showing that conversion is complete. This is coming from the folks at BYO and Kai Troester. The summary is that at the point that an iodine test indicates that conversion is complete, the gravity of the wort will continue to increase for a fair amount of time afterwards. I *think* a hydrometer should work to show this change over time, but I know that a refractometer will work due to the simple experiment of gravity checking a solution of starch (hydro incorrectly reads gravity while a refract correctly does not).

I do not doubt that conversion can take place much quicker in a finer grist, AND that conversion can truly be complete much sooner than the ~60min standard for normal-crush grists. However, I do think that finer grist mashes and conversion completion need more experiments from more than one source - not that I don't believe RM-MN but that multiple sources should be able to show the same result (or close to the same result).

How this all relates to an acceptable drop in mash temp, I don't really know, but I do know that conversion can be hampered by too much drop in mash temp

Source: http://braukaiser.com/blog/blog/2011/03/04/basic-brewing-radio-on-mash-conversion-and-iodine-test/
Source: http://media.libsyn.com/media/basicbrewing/bbr03-03-11iodine.mp3 (emphasis on the ~22:00-30:00 section)
Source: http://www.braukaiser.com/wiki/index.php/Iodine_Test

 

[RM-MN]

From what I'm reading, hearing, gathering, the iodine test is not an accurate way of showing that conversion is complete. This is coming from the folks at BYO and Kai Troester. The summary is that at the point that an iodine test indicates that conversion is complete, the gravity of the wort will continue to increase for a fair amount of time afterwards. I *think* a hydrometer should work to show this change over time, but I know that a refractometer will work due to the simple experiment of gravity checking a solution of starch (hydro incorrectly reads gravity while a refract correctly does not).

I do not doubt that conversion can take place much quicker in a finer grist, AND that conversion can truly be complete much sooner than the ~60min standard for normal-crush grists. However, I do think that finer grist mashes and conversion completion need more experiments from more than one source - not that I don't believe RM-MN but that multiple sources should be able to show the same result (or close to the same result).

How this all relates to an acceptable drop in mash temp, I don't really know, but I do know that conversion can be hampered by too much drop in mash temp

Source: http://braukaiser.com/blog/blog/2011/03/04/basic-brewing-radio-on-mash-conversion-and-iodine-test/
Source: http://media.libsyn.com/media/basicbrewing/bbr03-03-11iodine.mp3
Source: http://www.braukaiser.com/wiki/index.php/Iodine_Test

I've been trying to get more people to try the shorter mashes, even the 20 to 30 minute mashes, but I don't see any raised hands. If the iodine test doesn't accurately determine when mash is over, how much more time is needed? Another 5 minutes or another 50 minutes? If I consistently get 85% efficiency, how much more will I get if I wait longer? I used to do a 60 minute mash, then a 30, now a 10 and the efficiency seems to stay the same.

 

[The_Glue]

I've been trying to get more people to try the shorter mashes, even the 20 to 30 minute mashes, but I don't see any raised hands. If the iodine test doesn't accurately determine when mash is over, how much more time is needed? Another 5 minutes or another 50 minutes? If I consistently get 85% efficiency, how much more will I get if I wait longer? I used to do a 60 minute mash, then a 30, now a 10 and the efficiency seems to stay the same.

Is mashing for 30 minutes is the same as mashing for 60 minutes but with a properish temp range only for the first 30 minutes (like 152-146F) and then stop caring about the temperature and letting it go as low as it wants?
Because if not then i might should try 30 min mashes from now on, i did the previous thing up to now but i did only 8 or 9 batches so far.

 

[RM-MN]

I listened to the entire podcast (http://braukaiser.com/blog/blog/2011/03/04/basic-brewing-radio-on-mash-conversion-and-iodine-test/) and what I heard (interpreted) was that when you got a negative iodine test there was no more starch in the wort but that there was still conversion and extraction from the larger particles of grain. That should tell people that crush quality affects the efficiency of conversion and extraction (which we tell people who complain about poor efficiency) and that mashing longer is a work around for a poor crush. Since I mill my grains very fine, the time to get conversion is very low. During the podcast they kept referencing testing with iodine every 5 minutes and my conversion with that finely milled grains never takes 5 minutes.

 

[stpug]

I guess I didn't quite interpret the same thing as you, close but slightly different. What I got was that after you obtained the negative iodine test you were left with chains of starches and sugars that were less than meets the requirement for the iodine molecule to fit into, thus no more color change, however starches DO still exist and will be converted to sugar given more time. However, you're absolutely correct that crush "quality" matters and the finer the crush the quicker the processes can take place.

It's all very interesting and intriguing to me. I might find myself playing with a small batch in the short future (like I don't waste ENOUGH time doing beer-related tasks already ).... oops, almost forgot I need to top crop a batch in a couple hours

 

[Jayslay]

Hmm, this is very exciting and curious content. I'm trying to find ways to shorten my brew day. I just got an immersion chiller which saved me 45 minutes. My mash is one item I was hoping I could shorten for some beers, and I do have iodine and a watch plate now for tests, so I may do my own experimentation with this. Even just knocking it down to 40 minutes or so would be nice... But not if it impacts the worts qualities negatively.

 

[dobe12]

I posted my conversion test in another thread. 9.75lbs of grain, fine crush, 151F mash temp. Used a refractometer. A good bit of conversion happens in the first few minutes, but continued up to and past 30 minutes. Iodine tests don't tell the whole story.

 

[stpug]

I posted my conversion test in another thread. 9.75lbs of grain, fine crush, 151F mash temp. Used a refractometer. A good bit of conversion happens in the first few minutes, but continued up to and past 30 minutes. Iodine tests don't tell the whole story.

^That's a very important sentence to take note of. A refractometer is your best friend for watching gravity changes during the mash as it is not affected by unconverted starches.