Baking and scorching are two of the most common roast defects. I think it’s pretty apparent when they’re grossly present. If your beans are tipped, you’ll taste it as a burnt, medicinal or cacao nib edge. If your bean temp (BT) rate-of-rise (RoR) equals zero at any point, you’ll taste it as a flat, insipid, unsweet quality. But in between these extremes, it gets a little murkier. And to some extent, I’m not sure if there is a correct balance where absolutely no baking or scorching occurs. I think a lot of American third-wave palates view minor scorching as a non-issue and a lot of Nordic palates view minor baking as a non-issue.

I’ll attempt to delve into this a bit with examples from some roasts over the past few weeks. I won’t offer anything definitive, so I’d love your thoughts.

All roasts are in a Quest M3, 150.0g charge. The red line is maximum environmental temperature (MET) and dark blue is bean temp (BT). Light blue is the rate-of-rise of bean temperature, so degrees F per minute. All roasts are in the Nordic-to-city range, 12.0 to ~13.5% WL (weight loss). I don’t mark first crack (1C) end since my roasts finish either during first crack or right after it ends.

First, let’s look at a profile that’s teetering on the brink of baking but manages to taste absolutely lovely. For reference, all profiles are provided in full-resolution here: http://imgur.com/a/nlYNy

I was working with Sweet Maria’s Gatomboya AA right after receiving it. It was really fresh and moist. I stretched out the drying phase extremely long - 6:18. Then a fast ramp and fast finish. I’ve posted about this roast before, but it was great - insanely sweet with juicy tartaric acidity.

On the other hand, here’s a roast that looked OK to me but fell flat.

This was a roast with a Borboya Yirgacheffe. I mostly hit my targets (4:30-3:15-1:45). And yet it came out tasting flat, papery, and baked. The one thing I do notice is a flattening of RoR during development. The roast never stalled out, but RoR steadied out at a low ~8 F/min. So here we have some conditional support for Rao’s idea that flat RoR / linear profiles exhibit reduced sweetness.

This is a Cauca Colombia microlot from Banexports / Mill City kindly sold to me in a 3 lb. increment by Bodka Coffee. There’s a similar plateau in the development phase and a resulting flatness.

I think it’s interesting to see how in both of these flawed cases, I moved into development with less momentum and had to power through the tail end of first crack. It seems that - #pocketscience warning - perhaps sugar caramelization or some other reaction may have stalled out in first crack.



As a result, I think I’ll be trying to move into 1C with a little more momentum. Rather than going in at 470-480 MET and trying to dial in a steady RoR with Artisan’s HUD feature, I’ll go in a little hotter at 480-485 F MET and then dial back power to cruise in. Because the approach is less linear, Artisan’s HUD functionality will be less useful, but such is life.

I had been thinking that higher moisture coffees are less prone to baking, but I’ve now revised my speculation. Rather, I think that higher moisture coffees encourage the roaster to not bake coffee. So it’s a result of the coffee but not a property of the coffee itself. Since higher moisture coffees release water vapor in first crack and decelerate the roast, they encourage the roaster to go into 1C with lots of momentum and decelerate. Whereas drier coffees offer less resistance and “encourage” you to just maintain a steady RoR in 1C.

I’ll leave you with a couple questions for thought. Here is a profile that tasted lovely as a 21% extraction V60 but flat as an 18% extraction V60.

[ignore the glitch at ~3:30; this is a profile of a Borboya Yirgacheffe]

1) Is a coffee “baked” if it comes across as such only at lower extractions?

And another for you, following somewhat reduced extractions from super-light, longer-dry profiles…

2) If a coffee is less extractable, is it necessarily not fully-developed?

(Rao and company would argue so, but I am not entirely convinced.)