The Smells of Heaven

If you know me, you might know that I’m a bit of a coffee nut. We have a fairly nice espresso machine and grinder at home (Rancilio Silvia and Rocky) and I build at least two cappas most mornings. I think I’m pretty decent at it, to the point where we like the drinks we make at home much more than any of the local coffee houses.

I’d been re-reading a fun online novelette called Espresso! My Espresso! by Randy Glass which chronicles his journey learning to make really great espresso. His experiences were one of the deciding factors in going with the Silvia for our home machine, though Randy went one step further than I did; he started home roasting. When we picked up Silvia, we were not sure this whole thing would work out and didn’t really want to go all in right off the bat. Silvia has a great resale value and I figured if we hated it, I wouldn’t be out too much money.

Nearly a year and a half later, I no longer have any concerns about selling Silvia. In the intervening time, I’ve spent countless hours studying proper technique, trying out new ideas, reading alt.coffee, installed a PID to better control temperature, purchased a better grinder (the Rocky), bought a high-precision scale to measure bean weigh down to the tenth of a gram and spent a fair bit of time trying to put my old thermo class to work. It’s a very enjoyable hobby and it produces a rather tasty beverage each morning. After started to re-read Randy’s story, my interest in home roasting perked up a bit. There are some financial advantages to it too; green beans cost around 50 to 75% of what roasted beans do and they last up to a year. We’ve been buying 5lb bags of Black Cat from Intelligentsia and freezing off most of it. It works, but it’s a pain and the quality does seem to suffer when we get into that last pound and a half or so.

When my co-worker AJ offered to send me an air-roaster he wasn’t using (an iRoast), I jumped at the chance. I’m now home roasting too; yet another path to walk down and learn, and so far it’s been quite a good time, if a bit frustrating. The iRoast is essentially an air popcorn popper on steroids, with a bunch of nice features for roasting coffee. Unlike a popcorn popper, the iRoast can be programmed. The program consists of three stages; you set the air temperature for each stage and the duration and the roaster tries to send air of that temperature over the beans for the period.

I say “tries” because it seems like the temp you set and the temp actually delivered are wildly different. I’ve ordered a little k-type thermocouple (a fancy thermometer) to measure the temp in the mass of roasting beans to get a better idea what’s going on, but for now I’m going based on appearance, smell and the “cracks.”

When you’re roasting beans, there are stages the beans pass through. During the progression there are two “cracks”, that is two audible clues to what the beans are doing. The first crack signals the stage where the beans would now produce drinkable coffee and somewhere in the second crack is the usual desireable level of roast for espresso drinkers. Sadly, hearing the cracks over the whir of the iRoast’s fan is a bit hard. I’ve found that by specifying a fairly high level of heat near the end of the roast (slowing the fan down) makes it easier to hear, but I’m still not totally sure what I’m listening for. The thermocouple should help out in that regard.. More when it arrives.

Anyway, today I roasted up some Sumatra Blue Batak “Tarbarita” Peaberry to what I think is City+, maybe Full City. I decided to start keeping a journal with roasting times and temperatures.. Here’s the data from today. Ambient was 67F, it was raining, and these temps are all from the on-board temperature sensor on the iRoast.

Time Temp Notes
0:30 221 first stage at 360F
1:00 235
1:30 244
2:00 250
2:30 255
3:00 257
3:30 259
4:00 262
4:30 264
5:00 266 second stage at 470F starts
5:30 288
6:00 293
6:30 304
7:00 306
7:30 307
8:00 309 third stage at 455F starts
8:30 311 first crack starting? pretty sure.
9:00 311
9:30 316
10:00 318
10:30 324
11:00 327 very active cracking noise
11:30 335
12:00 340
12:18 342 manually stopped. slight sheen on beans?

Get to try it out on Thursday once it’s had a chance to rest. I’ve never had or made a single-origin espresso before, so it should be interesting…