All grain home brewing

can't you do step-mashing in a cooler by removing some of the wort, heating it, and pitching it back into the cooler? i've never tried it before, but I asked the guy at my local hbs about this exact question and that's the answer i got.

 

That is how you do a decoction mash - but not at step temperatures. If you are doing a protein rest at 125 and then need to raise the temperature to a 150 scarification, you would be decocting unconverted mash, raising its temperature well above the point where it denatures the alph and beta amylase in that decocted portion of the mash. That is going to effect the mashes ability to convert. It might work if you had no other option, but you'd probably be better off using well modified malt instead of doing the step mash

 

Yes. That's known as a 'thin decoction' (in contrast to a 'normal' decoction in which you're removing and boiling grains along with some wort). I wouldn't do this with a grain bill where the diastatic power is borderline, for reasons WickedSluggy mentioned.

 

ah. makes sense.

 

If you want to step mash in a cooler you will have to add more heat. You can thin the mash by adding hot water, you can build a RIMS/HERMS type of deal and exchange the heat into the mash, or you can transfer to another - heatable - vessel to heat for each step. Just transfer back to the cooler for the rests if you want. If you are worried about HSA, Dr. Bamforth seems to poopoo the idea. He's has written one or two books about brewing so you may want to take that with a grain of salt . Or take the above answers about how to do a step in a cooler. Oh wait.