mgrayson wrote:The inlet profile came out fairly dark at RoastVision 13. The exhaust profile fairly light at 24. This was Yemen Mokha Hajjah, 75g on a Pro100. I roast for espresso, but I've been surprised by roasts of all light/dark levels. I'll report back after I try them.

Did you keep a record of the roasting session for the inlet profile? I'm curious how it translated to the ET readings...

Indeed. Long development, but tastes good so far.

Thanks for posting the data!

In case anyone else was wondering (measured from the screen cap image):

Inlet / ET / drop
149 / 97 / 52
199 / 144 / 55
224 / 172 / 52
238 / 191 / 47
243 / 203 / 40
255 / 219 / 36
260 / 228 / 32

The drop between inlet and ET was 37C when you marked FC. Also see the RoR slope tilt downward around the 7-minute mark, perhaps as a portend of second crack. You didn't mark second crack, but I imagine it got really close - or was silent.

So, largely linearly-declining RoR to first crack, then steady for the rest of the roast. I suppose that allows the user to listen for FC, then decide when to push the drop button per their desired roast level - or let it ride to a Full City/City+ (presuming you're getting light oil spots on the beans). The linear temperature ramp after FC maximizes the separation between the increasing roast levels, making it easier to get the timing right.

In case any drum roaster pilots are watching: what are the tasting notes when the RoR flattens out during development?

p.s. I'm really jealous of how noise-free the RoR curves are in the Pro app.

Regardless of roaster, if BT ROR flattens for too long during development you'll get baked coffee. It'll be dull, maybe papery, lacking sweetness and acidity, etc. If the time isn't too extended, you would have a mellowing of acidity and some more caramelization. With flat ROR in development, you can lose some of the distinct flavors.

Not sure how many of you are roasting on the lighter side, but this profile has been working exceptionally well for me, who has never roasted before...


Here's a link to the profile:
Stretched Filter Light +


This is a modified version of the Buie Bora Filter Light + profile from the "Around the World Starter Pack" that comes with the Ikawa Home Roaster System.

The goal with the changes to this profile were to pump a bit more heat into the beans at the beginning with a higher 45s starting temperature of 240C, followed by a profile that stretches the original milestones progressively and looks a bit like Gary McCormick's ROR profile. I added then point and adjusted the points on either side of the new point to take the resulting aggressive slope change out of the curve.

The goal is an evenly roasted bean with high solubility and aroma with minimal roast characteristics imparted. I'm using 65g charges, so I'd expect a 100g roast to yield slightly more development at the same overall roast time.

This measures 117 on the DIY Roast meter with 40s development time and was dropped at 5:10 (13% dev and 9.7% loss). With this bean, FC starts a bit earlier on the curve than the ROR profiles thanks to the heat added earlier in the roast.

If you like light roasts, I'd consider giving this a try. So far only one bean has needed close to the full 6 minute roast time when shooting for 40s development time (5:52 drop, 11% dev and 15.5% loss). So far I haven't found any baked flavors present with the slight decline on temperature at the end.

Bear in mind with roasts this light, they will need 2-3 weeks rest to really come alive, so don't be alarmed if you get some initial grassy flavors. Once rested, I'm finding these roasts to deliver incredible depth of flavor and aroma with my crummy pour over skills using 64MP burrs and a Melitta dripper, as well is wonderful single shots on the Micra. My preference is juicy acidity with ample sweetness to balance it. Chocolate, caramels and nuts are going to be playing second fiddle to florals and fruits roasting this light, so it isn't for every green out there.

Cheers!

- Jake

drgary wrote:Regardless of roaster, if BT ROR flattens for too long during development you'll get baked coffee. It'll be dull, maybe papery, lacking sweetness and acidity, etc. If the time isn't too extended, you would have a mellowing of acidity and some more caramelization. With flat ROR in development, you can lose some of the distinct flavors.

I can understand baked-ness from zero RoR (stalled?) roast - like an oven. But flat RoR is still increasing BT - and increasing faster than a declining RoR. This may be one of those "it's empirically verified - don't try to understand it" things, but a LOT of the supplied exhaust profiles for the IkawaPro have straight temperature profiles with maybe one bend after FC, so only TWO values of RoR for the whole roast.

I could have the whole "roast flavor" thing wrong and it stems from a too cooked outside of the bean and too undercooked inside, which would argue FOR declining RoR. I'm really trying to understand. I have yet to see a "why declining RoR" that didn't amount to "we asked a bunch of good roasters what they do and that's what they do." This is not a criticism! I'll take expert practice over molecular gastronomy any day. Is the goal a more evenly cooked bean?

Jonk wrote:I do. If someone with a BT reading would like to post what Jake's profile looks like with an example roast I'll try to make a Kaffelogic profile from that.

I made this with input from the Kaffelogic users Discord.

When I wrote about BT ROR flattening during development, I cautioned against that being for "too long." We're not measuring BT ROR, or course. Gary referenced wanting feedback from people with drum roasters, so I was partially addressing that, too, when describing results in terms of BT.

I think a key part of dialing in your use of any roasting machine is tasting your results and doing that over different beans and roast levels within your range of preference.

Sometimes I want to stretch the roast a bit with flat BT ROR to mellow out sharp tastes. So it depends.

Here is a Kafelogic roast profile that is getting similar results to the Ikawa I posted: