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?
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.
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.
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 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.
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.
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?
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!!
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.