DIY Coffee Roasting

Roasting your own coffee at home is a lot easier than most people ever imagine. You don’t need special, dedicated equipment, though it can be nice to have. All you need is green coffee beans, a heat source and something to roast your unroasted coffee beans in. While professional coffee roaster can – and do – write entire books about the particulars of roasting coffee, you don’t need to know about internal bean temperature, roast profiles and spectrum curves to roast coffee at home any more than a good cook needs to understand complex chemistry to bake a great cake. All you need is a good understanding of the basics of DIY coffee roasting.

How to roast coffee at home
DIY Coffee Roasting

Home Roasting Equipment

There are many different methods of roasting coffee at home, and ingenious people come up with more all the time. The most common methods, though, are stovetop roasting, air popper roasting and roasting in a home coffee roaster.

Stovetop Roasting

All you need to roast on top of the stove is a heavy, flat-bottomed pan with good heat distribution. Many home coffee roasters swear by a good cast iron frying pan. Others get a little fancier and invest about $25 in a stovetop popcorn popper like the Whirley-Pop Stovetop Popcorn Popper, a heavy stainless steel covered pot with an integrated stirring handle that will keep the beans in motion.

Air Popper Roasting

Popcorn poppers are among the most popular utensils repurposed for DIY coffee roasting. The hot air poppers are essentially fluid bed coffee roasters – they use a flow of hot air to keep the coffee beans in motion as they roast. They’re a very inexpensive way to get into home coffee roasting, especially if you find your hot air popper at a local thrift store. The most important thing to keep in mind if you decide to try roasting coffee in a popcorn popper is that you choose a model that vents the hot air in from the sides of the popping chamber, not those that blow the air up through a grate or vents in the floor of the chamber. Chaff can fall through the grates onto the heating element, causing a fire hazard in models that blow hot air up through the floor.

Dedicated Coffee Roasting Machines

Over the past few years, home coffee roasters have gained a number of new choices if they decide to invest in a dedicated coffee roasting machine. The prices run from about $175 to around $1,000 depending on many factors. At the low end of the scale, you’ll find small hot air poppers like the FreshRoast Automatic Coffee Bean Roaster, which is about the size of a countertop coffee maker and roasts about 5 ounces of coffee at once. In the mid-range, you’ll find more robust machines like the Behmor 1600 Home Coffee Roaster, a drum coffee roaster that can roast up to a full pound of unroasted beans at once. The Hottop 9oz Programmable Model: B Coffee Roaster is positioned at the top of the home coffee roasting machine range. The HotTop roasts up to 10.5 ounces of coffee at a time, and lets you program numerous variables, including time, temperature, heater power and fan speed, and gives the roaster total control over the entire coffee roasting process. The HotTop also has a dedicated cooler to quickly cool your beans when they reach the right roast temperature.

Other Coffee Roasting Equipment

In addition to a roasting utensil, you’ll also need:
– A wooden spoon, paddle or stick to stir the coffee while it roasts
– A pair of colanders or strainers to cool coffee after the roast
– Optional: a fan to help blow off chaff and disperse smoke
– A well-ventilated area

Where to Roast

The last item on the list above is vitally important. Roasting coffee can be a very smoky affair. If you try to roast indoors without good ventilation, you’ll be setting off every smoke alarm in your house. Many beans also throw off a lot of chaff while they’re roasting, so you may want to roast somewhere that’s easy to sweep up – or where the chaff can simply blow away.

How to Roast

The details of roasting coffee depend a great deal on the roasting method you choose (and the three presented above are only a small selection of the many things people use to roast coffee, for the record). This is the general process, no matter what method you’re using.
Preheat your popcorn popper or roasting pan.

Add a measured amount of unroasted coffee beans.

If necessary, stir the coffee beans frequently to keep them in motion.

The beans will lighten from green to light tan, and then start darkening through the stages of brown.

You’ll eventually start hearing little popping sounds, like popcorn popping, as the moisture inside the roasting coffee beans begins to expand. This is first crack. And, just like popcorn popping, first crack can go on for some time, with the pops coming faster and then slowing down.

After first crack ends, you’ll usually get a period of quiet as the beans turn darker. It can last anywhere from a minute to several minutes. Many roasters end their roast sometime during this period, based on the color of the beans.

Listen for the second crack, another period of popping. Unlike first crack, which is very distinct, second crack is quieter, and sounds a lot more like Rice Krispies snapping and crackling after you add milk. At this point, you’ll want to watch your beans carefully because they’ll go through roast stages very quickly.

When the coffee is almost as dark as you want it, turn off the machine and quickly dump the roasted coffee beans into a steel colander or strainer. Pour them back and forth between two bowls, colanders or strainers to cool them quickly and stop the roast.

A Few Things You Should Know

These are a few things you should know, no matter what method you choose.

Volume Makes a Difference

You might think that fewer beans will roast faster, but that’s not always the case. In a hot air popper, for example, if you don’t add enough green coffee beans, your roast may never reach critical temperatures. The beans themselves hold the heat, so you need enough of them.

You’ll Need All of Your Senses

Or most of them, anyway. As you get familiar with coffee roasting, you’ll learn to judge the level of roast not only by the color, but by the sounds and smells of the coffee beans as they roast.

Everything Affects the Roast

There are so many factors that can affect how well your coffee roasts that it’s amazing anyone ever gets consistent roasts from one batch to the next. Among the things that make a difference are the weather – temperature and humidity in particular – the wattage of your coffee roasting appliance and the line wattage – you may find that you get far better results when you plug your coffee roaster (or popcorn popper, as the case may be) into one outlet than you do in another, and, of course, the beans.

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