Unroasted, or green, coffee costs less, too, so you'll save money in the long run. In fact, you can get your hands on green coffee for as little as $4 to $5 a pound. Sure, the idea of home roasting might sound intimidating at first, but the payoffs are huge. Here's how to get started.
These are raw, or green, coffee beans that have not been roasted.
Tyler Lizenby/CNETFrom raw to roasted coffee
With enough heat energy applied to green coffee, the hard structure of a bean breaks down to release its complex mixture of contents. This cocktail includes everything from water to sugars, proteins, fats and, yes, caffeine.
The high temperature of roasting chemically alters many of these compounds (such as by caramelizing sugars and oxidizing lipids, proteins and starches), and ultimately creates what we expect to see, smell and taste in freshly roasted coffee.
Read more: The best espresso machine for 2020
Gather the tools and hardware you need for this project.
Tyler Lizenby/CNETBuild a backyard roaster
You can build a coffee roaster easily from inexpensive items you can buy at a hardware or kitchen supply store. Here's a list of the parts I used.
To begin, drill a hole through the center of the base of each colander with a three-eighths-inch metal drill bit. Next, spin one nut and one wing nut onto one end of the threaded rod (go about halfway) and from the opposite side, slide one washer down the rod. Then, slide one of the colanders onto the rod through its drilled hole, next to the washer, with the open side up. Follow with another washer and two regular nuts, and tighten all nuts so the colander stays fixed in place.
In the same way, attach the other colander to the rod so that the rims of the bowls face each other. Leave a 6-inch gap between the two vessels, hold the rod vertically and add your green coffee to the lower colander. It's a 5 quart model with plenty of room for the 1 pound batches I suggest you roast. Finish by slipping the second colander down to close the gap and securely tighten the nuts.
The roaster you've constructed should rest above the burners and be able to spin freely around its threaded rod.
Tyler Lizenby/CNETPrepare your barbecue
I suggest using a gas grill to roast coffee. These grills have responsive burners powered by propane. That makes their internal temperature easier to control compared with charcoal grills. Begin by removing your grill grates, heat diffuser (bars or pan) and warming rack. If your grill has a slot for a rotisserie accessory, use this opening to place the threaded rod across the burners. If not, lay the rod across the hood's sides with the hood open. (Many grill hoods have sections cut out of their sides to make room for accessory mounts when closed. Line the rod up to match these gaps.)
Your roaster should now be suspended and centered over the barbecue's burners. To spin the apparatus, connect an electric drill to one end of the roaster's rod as if it were a drill bit and tighten the drill's chuck jaws around it.
Use a cordless drill as a motor to rotate your roaster.
Brian Bennett/CNETAn adjustable hose clamp wrapped around the drill's trigger is a simple way to apply steady pressure and spin the roaster drum at a constant rate. Aim for 120 rpm (I count revolutions for 30 seconds and then double the number).
That's quick for a rotisserie motor (10 to 55 rpm) but easy for a power drill (600 to 1,500 rpm). The goal is to mix the beans quickly enough so heat hits them evenly, yet slowly enough to minimize stress on the drill and avoid loosening any nuts and washers.
Fill your roaster with raw coffee beans.
Tyler Lizenby/CNETRoast, baby, roast
How long any given roasting session will take can vary greatly depending on factors like the coffee variety, how hot your roaster gets and whether you'd like a light, medium or dark roast. As a general guide, expect a small batch of beans (1 pound or less) to take about 10 minutes.
Fire up your grills burners and start roasting.
Tyler Lizenby/CNETStart by firing up the grill and turning the burners up to maximum. Close the hood to let the grill cavity warm up and when the grill thermometer hits 400 degrees Fahrenheit, turn the burners down to medium. Next, add green coffee to the drum, tighten the two colander halves together, carefully set the rod in place and start spinning.
Now you're ready to close the hood while keeping your ears, nose and eyes peeled to monitor what's going on inside. It's OK to take a few quick peeks, but open the hood too many times and you risk losing vital heat. Ideally, you want to keep temperatures in the roaster consistently between 400 and 500 degrees Fahrenheit. Since it's difficult to mount a heat sensor inside a spinning roaster, just use your grill's built-in thermometer instead.
Pay close attention to what you see, hear, and smell as the beans roast.
Tyler Lizenby/CNETListen out for the pop and don't burn your beans
The first change happens visibly when the beans shift from a muddled green to yellow to a darker golden hue. As the beans' internal temperature approaches and exceeds the boiling point of water, steam forms and trapped water vapor fights to escape.
When it finally does, the coffee beans begin to snap with an audible pop. In what's known as the "first crack," the beans split open down their middle and swell in size. At this point your beans are technically roasted, but they'll have a bright acidity on the edge of sourness. Drinking coffee from this roast level is perfectly fine, but to develop a traditional coffee flavor, you must go a little further.
Roasting coffee beans definitely creates a lot of smoke. That's why it's best to do this outdoors.
Tyler Lizenby/CNETAs the temperature climbs higher (435 to 445 Fahrenheit) fats, sugars and proteins break down. The beans are now roasting in earnest. Be careful at this stage because the pace of these reactions will speed up. If you're not paying close attention, you'll end up with burnt beans in no time.
As gases including CO2 (carbon dioxide) form, they cause another round of sustained snaps called the "second crack." The beans will then release oils giving them a shiny, glossy look. Roast longer and the beans will darken further to dark brown, even bordering on black. This creates dark roasts such as French roast.
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