Inside out with John Gant

Between pours at the Clover demonstration, I chatted with Gimme's roaster John Gant.

He is fascinating and fun to talk to, although this may not be apparent in most of the pictures I have of him. He usually looks very serious, as in this one where he poses with his heirloom Sivetz sample roaster:


(I think you can still buy one of these roasters direct from Sivetz for about $1000. :-) On the other hand, sometimes luck shines upon me and I capture John smiling in a photograph:

Anyway, at the demo I asked John about the statement George Sabados had made in Barista magazine: that the updose technique didn't seem to work with "two dimensional" coffees. Hmm...what's a two-dimensional coffee, you may ask? George says, "In the U.S., coffee is often roasted two-dimensionally, where the outside bean color does not vary greatly from the degree of color in the grind. This narrows the band of resistance to temperature and pressure, and therefore, my method of dosing is not recommended."

Gee, I said to John, I thought the idea WAS to roast more-or-less two dimensionally, at least for espresso. If the inside of the bean is a lot lighter than the outside, it tends to make a sour espresso. John got some roasted beans and a knife, and we cut open some beans. There were different shades of brown inside, because the bean doesn't have a uniform internal structure. Some parts necessarily roast differently than others. But still, the overall impression was that the inside was almost the same color as the outside.

Then I said to John that it seemed to me that the inside would ALWAYS be at least a wee bit lighter than the outside, because the roasting process necessarily heated the bean from the outside in.

Here's where he said something interesting that I hadn't thought of, and it's sort of the whole point of this post: John said that the beans DIDN'T heat solely from the outside in, because of the exothermic reactions that occur late in the roast. These reactions liberate heat and actually produce a heating effect that goes from the inside OUT.

Neat, that had never occurred to me and it alters the way I look at roasting. Those beans become little energy factories, and this exothermy provides heat that can help you roast from the inside out as well as from the outside in. IF you control the process with precision.

I guess this must be obvious to roasting pros, but it was a new concept for me....