Wednesday, September 12, 2012

Roasting Coffee

Now that I don't get free coffee every week, coffee beans have become a significant expense. Coffee at Intelligentsia, which is the nearest obsessive coffee shop to my apartment, often runs upwards of $20 per 12 ounce bag. Very high-quality green coffee from Sweet Maria's (a home roasting supply shop in Oakland) averages around $5 – $7 per pound. So home roasting makes economic sense. More importantly, home roasted coffee is the freshest of all coffee. I plan on roasting at least twice a week. Right now I'm roasting every day.

Of course, saving $15 a week isn't a big deal if you're going to spend $1000 on a coffee roaster. Fortunately, there are some makeshift alternatives that yield quite good results. In the past I've done some stovetop roasting, using a saucepan with a lid and an oven thermometer. Stovetop roasting approximates a drum-roasting environment (most commercial roasters are heated rotating drums), with roast times between 12 and 25 minutes. There are a few drawbacks to stovetop roasting, however. Even with a clear lid, it is very difficult to judge the beans' color, because the lid quickly fogs up. It's also difficult to achieve an even roast, though I've gotten pretty close by careful shaking of the pan. I'm sure my use of a heavy bottomed saucepan (clad copper or aluminum) helps with even heat distribution.

Another device that home roasters have discovered to work very well for roasting coffee is the electric popcorn popper. These devices shoot hot air through the popcorn (or coffee), both heating and circulating simultaneously. Air roasters roast much more quickly, in the range of 4 – 10 minutes. A faster roasting time generally means a lighter bodied, livelier coffee, so this method is well-suited to delicate wet-processed coffees and a light to medium roast. However, popcorn poppers have no built-in mechanism for adjusting heat levels, which depend mainly on the voltage of the outlet the popper is plugged into. Some home roasters adjust heat levels by putting on and taking off the lid, while others install heat dimmers and thermocouples. One can only roast 3 – 4 ounces of beans at a time in a popper, and it should not be used for consecutive roasts, lest the fan and heating element give out.

I recently bought a popcorn popper from Sweet Maria's (the West Bend Air Crazy, to be specific), but I plan to continue using both methods, at least until I decide that one is better than the other. Along with the popper, Sweet Maria's sent a sampler of 4 different pounds of green coffee: a dry-processed Brazilian peaberry; a wet-processed Java; a wet-processed Costa Rica; and a wet-processed Burundi. I think the Java and Brazil might benefit from stovetop roasting in order to emphasize their body and sweetness, while I expect the fruity acidity of the Costa Rica and Burindi to shine with an air roast.

There are various levels to which coffee may be roasted. These levels are generally determined by color, taste, and sound. At 400˚F the beans emit a loud popping noise, known as first crack. Stopping the roast immediately after first crack finishes results in a City Roast. Roasting further will result in (sequentially) City+, Full City, and Full City+. At 440˚F, the beans emit a snapping sound, known as second crack. Roasting into second crack will result in a dark roast. If one stops roasting during the second crack, the result is a Vienna Roast, which is a popular roasting level for espresso (it's also the level to which Peet's roasts most of its beans). Roasting further results in a French or Italian Roast, terms which are used inconsistently with respect to each other but always refer to a very dark roast. At this point, most of the flavor of the beans will be eclipsed by the flavor of the roast, though some coffees, such as wet-hulled Indonesians, are so pungent that the bean flavor is very evident even in a dark roast. As well as contributing flavor, higher levels of roasting increase body (at least up to a Full City Roast) and lower the perception of acidity (AKA 'brightness'; 'liveliness').

My first two roasts with the popper. Left: Costa Rica (City Roast); Right: Java (City+)