Photo courtesy of Anastasia Zhenina / Unsplash
Following last week's installment on dark roasting coffee, it seems fitting to offer a few tips for producing quality light roasts. The simplistic misnomer is that dark = long roast times; light = short roast times.
While visiting an SCA (Specialty Coffee Association) tradeshow in the mid-90s, we ran across a new coffee brand called, "White Coffee." It was named as such because it was barely roasted in order to preserve higher concentrations of caffeine. It wasn't actually white, but its astringency was shocking.
Most attempts to create light roasts by simply shortening roast times result in a sour and astringent cup. But exercising care to producing light roasts can coax some of the most exotic and subtle notes from a coffee bean. Our three tips are distilled thusly: Slow, Steady and Complete.
Slow. The main point here is the simple rebuttal to the suggestion that short roast times produce good light roasts. Whether you're roasting light or dark or somewhere in between, coffee beans need to be fully developed. If you roast too quickly, you will shoot past your light color target before you know it. Monitor your heat in a way that develops your beans but doesn't stall the roast. You shouldn't see much color change in your beans during the first couple minutes while the coffee beans gently soak up the initial heat. A light brown should start to occur at the 3 - 4 minute mark as you begin to notice the aroma of baked bread.
Steady. Again, you want to make sure the coffee continues to develop gradually and steadily throughout the entire cycle — without stalling. The beans should continue to increase in temperature (at a slower rate as you move through the cycle). As the beans continue to darken and you begin first crack, things can start to run off on their own as the beans begin to produce their own heat in this exothermic stage. LISTEN carefully to the rate of popping and adjust the heat up or down to slow or increase the rate of crack. You want steady cracking, but you're in the development time stage now and you should have your development time ratio (DTR) and discharge time calculated at this point.
Complete. Only if you have successfully roasted slowly and steadily will you be able to fully complete a quality light roast. If you fail to reach your full development time target before the beans start turning dark on you, you'll end up either over-roasting or under-developing your coffee, leaving wonderful flavor potential on the table. Again, the point here is that discharging early to get the color your aiming for is simply an incomplete roast.