BIAB - measuring mash temp

Temp drops from your strike water temp to the resting temp of your mash. You're adding colder grains (room temp) to hotter water than you want. They balance each other out. I would say that you want to start with strike water about 13 or 14F higher than your target mash temp. Have ice cubes on hand. I'd rather be a few degrees hot at first and try to cool than too cold and have to try to heat.

I also preheat the mash container. I go about 18F over my target temp and let it cool down a few minutes until I'm at that +13 +14 range.

I'd recommend stirring for the first 5 minutes. Don't measure temp. Just stir. It takes a few minutes for everything to balance out and the water to fully soak into the grains. This is the time you should be breaking up dough balls anyway. After that 5 minutes try to dial it in if you need to.

 

This always works well for me: http://www.brewheads.com/strike.php

 

The one BIAB batch I did (since ordered a cooler/ball valve), I overshot the temp by 12F, added the grain, stirred like crazy, tossed in a few ice cubes and wrapped it in a heavy blanket. I stirred twice during the 60 minute mash as well. When I took the temp, I stuck the probe in the middle of the grain, since, at least to me, that's where it's likely to matter most.

In terms of variation, I would attribute that largely to mass and surface area. If you're doing BIAB, I think the liquid itself would hold the heat longer than the bag of grain, but the closer you are to the sides of the kettle, to cooler it would be. But really all I know about thermodynamics is how to spell it...

 

Stir that shit, aim low and heat slightly to temp (if mashing in your kettle). I love BIAB.

 

I've noticed the same thing, very annoying to think you are perfectly on temp only to find out half of your mash is like 6 degrees hotter. Last night I stirred the hell out of it every 10-15 minutes and things went much better, most successful brew day yet!

 

I can't speak for all types of BIAB, but mash temps have a bigger potential for thermal loss with "No Sparge BIAB" mainly due to the increased water to grist ratio that comes along with it. The thinner the mash, the less you retain heat. As for general MLT stratification, I think it happens regardless of the mash type and that RIMS or HERMS is the typical solution (although that's usually in a non-BIAB application). Stirring helps (to a degree) to evenly mix the mash kettle temp, but also can lower the overall temperature.

 

Oh yeah and you can make an insulated mash jacket, but most of the building materials can't handle direct flame so you have to take it off if and when you need to raise the temperature. That minor inconvenience aside, they do help you to reduce the amount of heat lost over the course of the mash.

 

The thinner you mash the more water you have with the grist. Water retains heat like a ************. A thin mash makes it possible to stir your grains without doughballs. As for taking to a newbie brewer about HERMS and RIMS. Shame on you.

 

My thoughts were that water conducts heat better than grain, so a thinner mash might help to eliminate stratification (for the op, stratification = different temperatures in different sections of the mash tun), but I assumed that a thicker mash does a better job insulating against heat loss than a thinner mash would, no?

My past experience with BIAB doing mashes at 2.0 quarts per pound or higher vs. my present experience with 3 kettle brewing and mashing closer to 1.2 - 1.5 quarts per pound seems to support this notion. But that's only based on a casual observation, not science I must admit!

Let me also say that my reply wasn't in regards to hitting initial strike temps. It was only to maintaining them after they have been hit. It does make sense that, since the water is the heat source, the more water in the kettle = the more heat in the kettle. So perhaps that outweighs my assumption that the grains insulate better than water does?


This BYO article doesn't explain why, but does seem to briefly support your take. Again though, I'm not sure if the reference to mash thickness and temperature difference is about hitting initial strike temps or maintaining temp over the course of the mash.....


http://byo.com/mashing/item/1130-mashing-variables-techniques
Temperature differences

Everyone knows that temperature is important in mashing. However, one temperature-related aspect of mashing is usually left for the homebrewer to figure out on his own — temperature consistency and stability.

It’s fairly easy to end up with temperature differences in your mash. Variables that increase the potential for temperature differences include: direct heating of the mash, thicker mashes, less stirring of the mash, large initial temperature differences between your grains and strike water and large temperature differences between your target mash temperature and your mash tun.

 

Been doing a few more internet searches and found some additional forum posts (nothing I'd call reputable though) claiming that grist has less heat capacity (as well as heat conductivity) than water, so that would also support the idea that a thinner mash would lead to less temperature swing. So signs are initially pointing to inchrisin's advice being sound and mine being the opposite!

OK just found one by John Palmer....there goes the not reputable card!!!!

"The grist/water ratio is another factor influencing the performance of the mash. A thinner mash of >2 quarts of water per pound of grain dilutes the relative concentration of the enzymes, slowing the conversion, but ultimately leads to a more fermentable mash because the enzymes are not inhibited by a high concentration of sugars. A stiff mash of <1.25 quarts of water per pound is better for protein breakdown, and results in a faster overall starch conversion, but the resultant sugars are less fermentable and will result in a sweeter, maltier beer. A thicker mash is more gentle to the enzymes because of the lower heat capacity of grain compared to water. A thick mash is better for multi-rest mashes because the enzymes are not denatured as quickly by a rise in temperature."

 

Good digs. I think you've thoroughly redeemed yourself.