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General Category => All Grain Brewing => Topic started by: jtoots on August 25, 2014, 05:34:44 PM

Title: mash rest
Post by: jtoots on August 25, 2014, 05:34:44 PM
do you stir during the mash rest?  i haven't been, and i've noticed the following in a couple recent batches:

i'm using a cylindrical cooler for my mash tun.

-i hit my mash temp before closing the lid dead on.
-at the end of the mash i lift the lid and take temp readings in the middle and around the edges.
-around the edges the temp has gone down slightly, as expected (a degree or so).
-in the middle the temp has actually gone UP a couple degrees, as if the heat has migrated into the center of the tun.

any thoughts?  should i adjust my starting temp to account for this?  should i stir once during the rest?  all good, proceed as i have been?

thanks all!
Title: Re: mash rest
Post by: HoosierBrew on August 25, 2014, 05:41:37 PM
I stir thoroughly, until I get a pretty uniform temp throughout the cooler, then close the lid and leave it alone - the lid doesn't open until it's time to sparge.

EDIT - During the course of the mash, there would likely be some temp stratification throughout the cooler/tun, and temps usually drop a degree F or two, but no worries. A lot of good beer has been made in this fashion by a lot of brewers.
Title: Re: mash rest
Post by: erockrph on August 25, 2014, 05:58:13 PM
I tried stirring a few times. When I stirred I ended up losing about 5 degrees over the course of the mash. No stirring gives me about a 2 degree loss. Needless to say, I stopped stirring.
Title: Re: mash rest
Post by: jtoots on August 25, 2014, 06:14:18 PM
Thanks for the replies, gents.  Do you notice the same trend, heat gain in the center of the tun?

I'm thinking that, for example, if I'm aiming for a rest temp of 153, and the center of the tun is at 155-156 by the end of the hour, maybe I should start at 152 to account for this gain.  That said, the edges of the tun drop down to about 151, so the average temp is probably right where I want it and I shouldn't change anything.
Title: Re: mash rest
Post by: HoosierBrew on August 25, 2014, 06:58:30 PM
..... so the average temp is probably right where I want it and I shouldn't change anything.

That's always been my thought. Don't over think it. Good luck !
Title: Re: mash rest
Post by: davidgzach on August 25, 2014, 07:39:05 PM
Thanks for the replies, gents.  Do you notice the same trend, heat gain in the center of the tun?

I'm thinking that, for example, if I'm aiming for a rest temp of 153, and the center of the tun is at 155-156 by the end of the hour, maybe I should start at 152 to account for this gain.  That said, the edges of the tun drop down to about 151, so the average temp is probably right where I want it and I shouldn't change anything.

I've never had heat gain in the middle of the tun.  Are you sure you are mixing thoroughly to start?
Title: Re: mash rest
Post by: jtoots on August 25, 2014, 07:51:13 PM
Are you sure you are mixing thoroughly to start?

Yep, I'm sure, and didn't believe it the first batch I saw this.  Strange, right?  I'll be brewing this weekend, looking for it again. 
Title: Re: mash rest
Post by: denny on August 25, 2014, 08:29:18 PM
Thanks for the replies, gents.  Do you notice the same trend, heat gain in the center of the tun?

I'm thinking that, for example, if I'm aiming for a rest temp of 153, and the center of the tun is at 155-156 by the end of the hour, maybe I should start at 152 to account for this gain.  That said, the edges of the tun drop down to about 151, so the average temp is probably right where I want it and I shouldn't change anything.

How long do you stir when you mash in?
Title: Re: mash rest
Post by: jtoots on August 26, 2014, 12:21:14 PM
How long do you stir when you mash in?

I add water first, then add grains a couple pounds at a time, stirring after each addition.  Once all the grain is in and no clumps exist, I use my digital thermometer to get readings in a few locations while stirring to get temp down a couple/few degrees to my target temp.  The flaw I recognize here is that the thermometer isn't reaching down to the bottom of the tun... however, with all this stirring, I don't think stratification would be a major factor (and presumably the top would be the hotter region, and the vertical distance isn't all that significant especially for a 5 gallon batch).  I'd say all in all this takes 5 minutes plus although I've never actually timed myself.  I'll use a timer this weekend.
Title: Re: mash rest
Post by: denny on August 26, 2014, 02:42:25 PM
How long do you stir when you mash in?

I add water first, then add grains a couple pounds at a time, stirring after each addition.  Once all the grain is in and no clumps exist, I use my digital thermometer to get readings in a few locations while stirring to get temp down a couple/few degrees to my target temp.  The flaw I recognize here is that the thermometer isn't reaching down to the bottom of the tun... however, with all this stirring, I don't think stratification would be a major factor (and presumably the top would be the hotter region, and the vertical distance isn't all that significant especially for a 5 gallon batch).  I'd say all in all this takes 5 minutes plus although I've never actually timed myself.  I'll use a timer this weekend.

Well, it sounds OK, but without being able to read the temp all the way to the bottom I guess you can't know for sure.  Based on what's happened to me before, I'd guess that you don't have heat distributed well enough to begin with.  But that's just a guess.
Title: Re: mash rest
Post by: Plmac on August 30, 2014, 04:30:16 PM
Are you preheating your mash tun? How hot?  I don't worry about the end temp as much as getting my starting temp stabilized.  Conversion is usually done within 30 minutes and yes I let it sit for 60 minutes just in case.
Title: Re: mash rest
Post by: denny on August 30, 2014, 05:34:40 PM
Are you preheating your mash tun? How hot?  I don't worry about the end temp as much as getting my starting temp stabilized.  Conversion is usually done within 30 minutes and yes I let it sit for 60 minutes just in case.

I spent several years preheating the tun, then had a revelation...if I just tracked how far off I was without preheating for a few batches, I could come up with how much hotter I needed to make the water.  Works great and I haven't preheated in years.
Title: Re: mash rest
Post by: hopfenundmalz on August 30, 2014, 05:49:55 PM
Are you preheating your mash tun? How hot?  I don't worry about the end temp as much as getting my starting temp stabilized.  Conversion is usually done within 30 minutes and yes I let it sit for 60 minutes just in case.

I spent several years preheating the tun, then had a revelation...if I just tracked how far off I was without preheating for a few batches, I could come up with how much hotter I needed to make the water.  Works great and I haven't preheated in years.


Many do it that way. Easy, it is.
Title: Re: mash rest
Post by: Plmac on August 30, 2014, 06:43:58 PM
Are you preheating your mash tun? How hot?  I don't worry about the end temp as much as getting my starting temp stabilized.  Conversion is usually done within 30 minutes and yes I let it sit for 60 minutes just in case.

I spent several years preheating the tun, then had a revelation...if I just tracked how far off I was without preheating for a few batches, I could come up with how much hotter I needed to make the water.  Works great and I haven't preheated in years.


Many do it that way. Easy, it is.

Totally agree, I was just thinking if his mash tun was holding heat like a heat sink it could raise the temp.  I guess the real question, Is your beer coming out the way you expect it to?  To sweet?  Mouth feel? Final Gravity as low as you expected?  Mash temp to High?
Title: Re: mash rest
Post by: klickitat jim on August 30, 2014, 08:07:16 PM
Are you preheating your mash tun? How hot?  I don't worry about the end temp as much as getting my starting temp stabilized.  Conversion is usually done within 30 minutes and yes I let it sit for 60 minutes just in case.

I spent several years preheating the tun, then had a revelation...if I just tracked how far off I was without preheating for a few batches, I could come up with how much hotter I needed to make the water.  Works great and I haven't preheated in years.

If it took me several years to preheat my tun, I would try to find a better way too.
Title: Re: mash rest
Post by: denny on August 30, 2014, 09:33:37 PM
If it took me several years to preheat my tun, I would try to find a better way too.

 ;D
Title: Re: mash rest
Post by: HoosierBrew on August 31, 2014, 12:18:41 AM
Are you preheating your mash tun? How hot?  I don't worry about the end temp as much as getting my starting temp stabilized.  Conversion is usually done within 30 minutes and yes I let it sit for 60 minutes just in case.

I spent several years preheating the tun, then had a revelation...if I just tracked how far off I was without preheating for a few batches, I could come up with how much hotter I needed to make the water.  Works great and I haven't preheated in years.


Many do it that way. Easy, it is.

+1
Title: Re: mash rest
Post by: jtoots on September 02, 2014, 02:35:17 PM
Thanks for all your input everyone!!

So this weekend's batch went well... I didn't see as much heat gain in the middle as I've seen in the past.  My rise time was right at 5 minutes.  I used the ball valve on my kettle to transfer the majority of strike water into the mash tun, then poured the remaining amount on top.  I think there is significant loss doing it this way instead of just dumping, because I came in about 1.5 degrees below my target temp.  So I think I need to go with about 13 degrees above target temp as opposed to the 11ish that BS tells me to strike with.  I fixed this one by adding about 1/2 gallon of 168 degree water to hit temp.  On the other hand, my mashout volume was smaller so I just dumped, rise time more like 2 minutes, and I came in over target so had to do some stirring.

My rest target was 148, which I ended up at.  The rest ended at 147.5 at the perimeter and 148.5 in the center.

About 5 AG batches in now, starting to find my comfort zone and loving it!!  Two of the 5ish have been contenders for my best batches of 50 so far...  Can't wait for an Apple Oatmeal Stout this weekend!!
Title: Re: mash rest
Post by: morticaixavier on September 02, 2014, 02:38:36 PM
you probably don't have to worry about overshooting your mashout temp. unless your alkalinity is too high and the mashout temp was above 170 it's not going to hurt anything to be too hot. you are trying to denature the enzymes at that point.
Title: Re: mash rest
Post by: denny on September 02, 2014, 02:47:34 PM
you probably don't have to worry about overshooting your mashout temp. unless your alkalinity is too high and the mashout temp was above 170 it's not going to hurt anything to be too hot. you are trying to denature the enzymes at that point.

Actually, the mashout could be skipped entirely without any problems.
Title: Re: mash rest
Post by: morticaixavier on September 02, 2014, 02:59:06 PM
you probably don't have to worry about overshooting your mashout temp. unless your alkalinity is too high and the mashout temp was above 170 it's not going to hurt anything to be too hot. you are trying to denature the enzymes at that point.

Actually, the mashout could be skipped entirely without any problems.

also true. I only do one with no sparge and then because i'm adding water anyway, it might as well be 180* water.
Title: Re: mash rest
Post by: klickitat jim on September 02, 2014, 03:56:38 PM
Ok, I just woke up so cut me some slack. If you mash arount 145 you get short chain, highly fermentable sugars, right? 155 you get long chain, less fermentable, right. (I know there's some overlap too) So, let's suppose you mash at 145 long enough to get near 100% conversion. Then raise the temp to 155. Its not going to put the short chains back together is it? At least in my mind it doesn't seem likely, so I quit worrying about mash out. The only time I would mash out is if I were trying to get a wort that was not very fermentable,  like for a lambic. Then the mash out might stop conversion,  if I was using a low DP malt that converts slowly enough to actually pull that off.
Title: Re: mash rest
Post by: morticaixavier on September 02, 2014, 06:03:49 PM
Ok, I just woke up so cut me some slack. If you mash arount 145 you get short chain, highly fermentable sugars, right? 155 you get long chain, less fermentable, right. (I know there's some overlap too) So, let's suppose you mash at 145 long enough to get near 100% conversion. Then raise the temp to 155. Its not going to put the short chains back together is it? At least in my mind it doesn't seem likely, so I quit worrying about mash out. The only time I would mash out is if I were trying to get a wort that was not very fermentable,  like for a lambic. Then the mash out might stop conversion,  if I was using a low DP malt that converts slowly enough to actually pull that off.

the missing piece of the puzzle is that the beta amylase only works on one particular linkage on the sugar. when the alpha amylase goes to work it breaks the chain in a different place that actually makes more linkages available to the beta amylase. so a long 145 rest will allow the beta amylase to cleave everything it can BUT moving to a solid alpha rest will actually make even more sugars available to the beta to cleave.

at least that is my understanding.
Title: Re: mash rest
Post by: klickitat jim on September 02, 2014, 07:53:52 PM
I figured it couldn't be easy
Title: Re: mash rest
Post by: erockrph on September 03, 2014, 02:57:09 AM
Ok, I just woke up so cut me some slack. If you mash arount 145 you get short chain, highly fermentable sugars, right? 155 you get long chain, less fermentable, right. (I know there's some overlap too) So, let's suppose you mash at 145 long enough to get near 100% conversion. Then raise the temp to 155. Its not going to put the short chains back together is it? At least in my mind it doesn't seem likely, so I quit worrying about mash out. The only time I would mash out is if I were trying to get a wort that was not very fermentable,  like for a lambic. Then the mash out might stop conversion,  if I was using a low DP malt that converts slowly enough to actually pull that off.

the missing piece of the puzzle is that the beta amylase only works on one particular linkage on the sugar. when the alpha amylase goes to work it breaks the chain in a different place that actually makes more linkages available to the beta amylase. so a long 145 rest will allow the beta amylase to cleave everything it can BUT moving to a solid alpha rest will actually make even more sugars available to the beta to cleave.

at least that is my understanding.
Right, but I'd add that there is a point of diminishing returns. As you increase the temperature up towards peak Alpha activity you begin to denature the Beta amylase rather quickly. That's why I think a long, low Beta rest works just as well (if not better) than a step mash. Alpha amylase is active at those lower temps, but at a much slower rate. By giving enough time, then alpha slowly gets to chip away and feed more pieces to the beta amylase. Also, at really low beta rests you may get some limit dextrinase activity as well, which can even start to chew some of the dextrins that neither alpha nor beta amylase can digest.
Title: Re: mash rest
Post by: ynotbrusum on September 03, 2014, 11:18:14 AM
Agreed as to the reactions, but at the homebrew level, you can end up with a really dry beer using that longer beta rest (over 90 minutes).  At least that has been my experience.
Title: Re: mash rest
Post by: morticaixavier on September 03, 2014, 02:37:01 PM
one of these days I want to try the overnight mash, start at say 150 and just leave it till morning. see if I can get a big 1.090 saison down below 1.000 with no sugar.
Title: Re: mash rest
Post by: erockrph on September 03, 2014, 03:59:56 PM
one of these days I want to try the overnight mash, start at say 150 and just leave it till morning. see if I can get a big 1.090 saison down below 1.000 with no sugar.
I was pretty happy with the results doing a true step-down mash for my last barleywine. I started with half the grist in a BIAB bag and did a 30 minute rest at 156 to let alpha amylase do its thing. Then I pulled the grain bag and added the remaining grains. I rested at 145 for 2 hours after that. Went from 1.142 to 1.024 with Yorkshire Square yeast at 58F. I can only imagine what you could get out of a solid Saison fermentation using that mash schedule.

Regardless, I'd recommend going closer to 145 or even lower, rather than 150. Limit dextrinase starts to denature around 140F, IIRC. I do think that it plays a small role in super low temp mashes.