Before WWI, almost everyone roasted their own coffee, usually by stirring it in a cast iron pan as they needed it. Then came the advent of Maxwell House and Hills Brothers (right here in San Francisco!), and the craze of prepacked coffee was born. Over the years coffee culture has taken numerous turns, from the Italian cafes of the Beat era to the rise of chains like Peets and Starbucks to high end artisan roasters.

Roasting coffee at home is cheap, fun and you'll have bragging rights to some of the freshest, best tasting coffee around! Impress your friends and subvert the evils of the big coffee business. Your final product will take 10 minutes to make, be about half the cost of roasted coffee you buy at the store or cafe, and your initial setup can cost you $10 or less.

What you'll need
* A fluid air-bed roaster AKA popcorn popper ($10 new @ the corner drugstore, $1-5 at yard sales or thrift stores, see below)
* 1 bowl or receptacle
* 1 colander for cooling the beans
* measuring cup
* green coffee beans

Some poppers will work better than others, but the only detail is that absolutely necessary is air vents that are on the side of the popper, not the bottom of the chamber. See the picture for an example of side vents.

We've had successful roasts with the Poppery I & II, Kitchen Gourmet (Walgreens) brands, but there
are many others. Old popcorn poppers will sell on eBay for $30 ---- that's often because folks are willing to pay a premium to use them as coffee roasters.

There are a lot of excellent coffee roasting tutorials on Instructables! This one is based on an old IRL guide I wrote

Step 1: Aquiring Green Beens

Finding green coffee beans is not as hard as you might think. Coffee shops that roast their own are usually happy to sell to you, most will do so at half the cost of roasted beans. You can also find them at some health food stores (Rainbow in SF) and online. The going rate for good quality specialty green beans is about $4-7/pound, though it will be lower if you buy very large quantities and a lot higher if you're interested in super premium or usual coffees (cup of excellence, Kona, Jamaican Blue Mountain, or even Kopi Luwak).

Two great online suppliers are 7 Bridges Cooperative, which sells organic coffee roasting AND home brewing supplies, so you can get your fix of two awesome things in one place and Sweet Maria's, which has a virtual encyclopedia of coffee and home roasting information, many of the worlds very best coffees, often sourced directly from farmers.

An alternative source to the above vendors are online coffee bean buyers clubs, two are Green Coffee Co-op and Green Coffee Buying Club. I've had positive experiences with both!

Step 2: The Roast

Watch a video of coffee roasting at TinyPic

Depending on the size of your popcorn popper you'll want to add between 1/2 cup and 3/4 cups of green beans. The idea is to get them to bounce around so they roast evenly. Start conservatively and move up. The roasting process doesn't take long so you can always do two roasts back to back.

Put the top on your popper, a bowl in front as you would to catch popcorn. This is going to catch the coffee skins, called chaff, that will be expelled as you roast. Chaff makes great compost, especially for plants that like acidic soil. Sometimes it also likes to fly around and you'll find it in your hair later in the day.

You can remove the lid of your popper to take a look at your beans, stir them around if you wish. Over time they will get darker and darker, after you leave them in long enough you'll start hearing a 'pop' noise. This is called a ‘crack,’ your beans should roughly double in size. If you leave the beans longer they will experience a second crack.

Some varieties of coffee are better lightly roasted, others dark -- most will include some information on this or you can ask your local coffee shop. Everyone has their personal preference, so it's really up to you! Darker roasts have a stronger ‘roast’ flavor while lighter roasts preserve more individual bean flavor. Experiment!!

(See Roasting Table attached at the end of this document for more specifics on different roasts, wikipedia, or Sweet Maria's pictorial guide)

Note: Coffee roasting can produce some smoke, so if you are roasting inside you should do it near a window if possible. The darker the roast the more smoke you'll produce. Also be prepared to watch your roaster so nothing awful happens (it usually won't).

Step 3: Cooling and Storage

After your beans roast to your desired darkness, cool them quickly by dumping them into a colander and shaking things around until they're room temperature. Congrats, you have somewhere between 1/4lb & 1/2lb of home roasted coffee!

Leave out for 12 hours (to release CO2 from roasting), then seal in an air tight container for storage. Coffee typically tastes best 24 hours - 72 hours after roasting, you might be inclined to try it immediately, but it won't have the full flavor. Over time and some experimenting you'll see how the flavors rise, develop and fall. Happy roasting!

Step 4: Mods and Other Roasting Methods

Some folks like to get more out of their coffee roaster and make some modifications to improve performance. I will add more about these soon, but will list some of the common modifications so you can search for these elsewhere if you are so inclined.

Popcorn poppers contain a thermostat that limits the temperature. You can sometimes get a quicker, darker roast by increasing the heat if you remove this from the circuit.

Roasters have two parts: Something to move the beans and something to heat them. In the popcorn popper these two things are tied together. If you separate the two circuits you can have better control of the roast.

If you want to roast in larger batches you can remove the guts of the popper from their plastic housing and try extending your roasting chamber with a soup can!

Other Roasting methods

If you don't like the idea of roasting with a popper, or can’t find one there are a bunch of other ways you can roast coffee -- below are a few for inspiration

* With a metal dog food bowl + heat gun
* By stirring coffee in pan on the stove or in the oven
* rotating a drum over a fire or barbeque
* renting time on a real roaster from the pros
* buying a mini/home coffee roaster (~$100+)
* building your own (spaceheater + fan? you just need heat + motion)

Roasting chart image via Food & Agriculture Office of the United Nations