I need to up my roasting game, and wanted to pick the brains of you all.
My coffee is consistently "OK" but never great. It tends to have an astringent twang I can't put my finger on, regardless of the beans' origin or roast level I do. It is kind of flat and one-dimensional. My wife thinks it's too astringent. She can be brutally honest, and I value her feedback. She says it makes her tongue dry after drinking. When I have a cup of coffee from a good coffee shop, it has a certain warmth and complexity that mine lacks. I usually shoot for about a medium roast, though I've done a few lighter roasts. I tend to buy beans from Central/South America, and occasionally, New Guinea. I stay away from the "trickier" varieties, and I don't want to screw up expensive coffee, anyway.
Let me describe my roasting process.
I use the "heat gun/dog bowl" method. Heat gun is just one I bought from the hardware store and it's dedicated to coffee, nothing else. I clean out the gun frequently with compressed air to remove any hulls that might be sucked into the intake vents. I've never noticed any odd smells coming from the hot air it generates. Bowl is a stainless mixing bowl, maybe 2 quarts, rounded with a flat bottom. During roasting I constantly stir the beans with a stainless wire whisk.
First, I preheat the bowl for about 30 seconds or so, then dump in 6 to 7 oz. of green. I hold the heat gun with its nozzle about 1 - 1.5" above the beans, a bit off-center, and whisk the beans to rotate them under the gun. I have no way to measure temp, so I go strictly by sound and use a kitchen timer to monitor the elapsed time it all takes. First crack usually begins around 5 - 7 minutes, and tapers off after another 2 or 3. Second crack starts around 7:00 to 10:00, and I usually stop right at the beginning of 2nd crack. I quickly pour the beans into a mesh colander and place that onto a "downdraft" box I made from a cardboard carton with a shop vac connected, and run that while constantly stirring the beans. Air is drawn downward and through the beans as I stir, and they are cool to the touch within about 60 seconds.
The beans always appear to be fairly consistent in color, and I rarely get more than an occasional quaker, which I cull. I let the beans "rest" for a day before grinding and brewing. I generally roast just enough beans to last a week or so and grind enough for the next day or two.
For brewing, I usually load up fresh ground into a plastic Keurig insert, or I brew a French press. I always drink it black. I have experimented with coffee to water ratios, but no real change. If I brew stronger coffee, I just get stronger astringency with it.
Am I roasting too fast? Too slowly?
Does my method need adjustment?
I never clean the roasting bowl, I just wipe it out with a paper towel after use. Could there be residue affecting batches?
Or does the heat gun method just have inherent limitations?
I'd love to get a Behmor, but that isn't in the cards for me at this time.
Any help would be appreciated!