Re-circulation Wort vs Mash temp K-rims

[Mastert1]

I have been searching around and others have talked about this question but I never seem to find a concrete answer.

I have a K-rims 2 vessel electric re-circulation system. Basically a Breweasy clone.

The question is: During re-circ mashing, which temp matters more for conversion and avoiding denaturing, Wort temp in the kettle or Grain bed temp?

My theory is that it's a sliding scale. As the gravity in the kettle increases the concentration of enzymes moves from grain bed to kettle.

Practically speaking, as long as I nail the dough in temp I should only be off by the loss in my system, about 3 deg. But, during temperature ramp up, you need to raise the temp of the kettle significantly to get a decent rise in the mash tun. People using the Breweasy have said that they way overshoot the temp in the kettle during ramp up. Wouldn't this denature the enzymes in the kettle?

Wouldn't a rims system also denature the enzymes in the tube during ramp up? Maybe I'm wrong and most of the enzyme activity takes place in the grain bed. Which makes more sense anecdotally.

 

[Weezy]

Imho....

1. There is a surplus of needed enzymes in modern barley malt,

2. Conversion of proteins is almost momentary. The trick (time) of mashing is extracting the proteins from the grain and making them available to the enzymes.

This is all evident by very fine milling in biab seeing conversion in just a few minutes.

That said, my geuss is the temp at the grain bed is the critical issue. That's where the enzymes and proteins are generated.

 

[RTL]

I think you mean conversion of starches, unless you are referring to a protein rest, which most of us never do.

If you are worried about denaturing your temp probe should be wherever you are adding heat. The enzymes will denature fairly quickly once heated to the denaturation point. Your hottest point will be where heat is added, which is likely not the grain bed. Though a second probe in the grain bed is good to ensure you are actually getting it to your desired temp.

I don't have a rims but I imagine if they are overshooting for a brief period they are killing a good chunk of enzymes (mostly beta), but not all of them or they would see very little conversion. Weezy is right that there is quite a large surplus of enzymes in moderm barleys. Alpha works very quickly at cleaving starches basically in half. Beta works about 1/3 the speed of alpha at cutting starches down from the ends making more fermentable sugars. So you should mainly be concerned when you are making a big beer or are trying to make a dry beer. For instance when I make imperial IPAs I overnight mash starting at 150, which finishes about 140 in the morning and I can get 90% ADF.