Roasting Coffee Beans At Home

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Roasting coffee beans at home is not so much a new idea as the revisiting of an old practice. Up until about World War I, people roasted their own coffee at home. But by the early 1900s, big companies began to roast their brands, and the art of home roasting went by the wayside. So in this age of so many modern conveniences, why are people starting to become interested in roasting coffee beans again? The biggest reason is freshness.

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Coffee beans actually begin as a small red fruit on a plant growing (for the most part) in a shady place at a high altitude and often in a remote location.(Check out our article on Fair Trade coffee to learn more). To get coffee from that plant to your coffee maker is a long journey, and every step along the way risks losing some of the freshness and flavor of the original bean. Most coffee is processed locally to the growers to remove the outer skin, the pulp and the inner skin. What remains is the inner seed -- or coffee bean. The bean is then dried and it becomes green. The green coffee is then shipped world-wide.

Green coffee beans are the most stable. Once roasted, coffee loses its freshness in 1-2 weeks.  Once  ground, freshness is gone in about 15-20 minutes.  So it is easy to see why perfecting the art of home roasting coffee beans can lead to a vastly superior cup of fresh brewed coffee.

There are many ways to accomplish home roasting.  You can start with a pan on your stove top or some people recommend a hot air popcorn popper.  Both of these will accomplish the roasting process.  But neither offer you the level  of control you will need to develop a consistently successful roasting process.  There are basically two types of home appliances designed for roasting coffee beans -- the drum roaster, and the hot air roaster.  Both offer a more automated, less messy and more consistent roast.

Regardless of which home roasting method you choose, roasting coffee beans goes through essentially the same basic process. As the beans are roasting, they must be kept in constant motion to ensure an even roast. Once roasted, the beans must be cooled very quickly or they will become over roasted. Also, roasting gives off smoke, so be sure you are in a ventilated area (your kitchen fan should work) and finally, be aware that the beans lose their outer skin (called chaff) during the roasting process and can be messy to clean up.

The roasting process can vary depending on how deep you want the roast to be.  As the beans begin to heat up, they turn from their original green color to yellow.  As the water inside the beans begins to evaporate, the beans start to steam.

First Crack. 

You'll hear a cracking sound as the roasting actually starts.  This occurs at about 400 degrees.

At this point, the bean has almost doubled in size and has gone from a yellow to a light brown color.  The sugars inside the coffee bean now begin to caramelize.  The structure of the bean begins to change, and the oils inside the bean begin to move outward to the surface of the bean.

Caramelization continues after first crack.  The beans continue to get bigger, the color of the beans continues to darken and the oil continues to migrate out of the bean. 

At any time after the first crack, your roasting process can be stopped.

Second Crack. 

If you are roasting for a darker bean, you will experience a second crack. This occurs at around 440 degrees.

The second crack is somewhat more explosive than the first.  At this point, the beans take on the characteristics of the roast, and the original characteristics of the bean are lost.  The bean color goes from light brown to very dark brown and the beans now have an oily sheen.

Be Careful! You do not want to roast your beans so deeply that you burn away all the natural sugar! If you get to that point, you've ruined your beans.

Even though you may have a timer on your roaster, you should monitor the progress of your roasting coffee beans so you can stop the process when your eyes and nose tell you it is time. Once stopped, remove the beans and cool them as quickly as possible (using a pair of colanders to pour the roasted beans back and forth works well to cool them down).

Your newly roasted coffee beans will continue to improve in flavor for the next 24 hours. So roasted beans should "rest"for at least 24 hours, and at most about 7 days prior to grinding and brewing. By giving your new beans that 24 hour rest period, you ensure that you will have taken the first step toward brewing the best possible cup of coffee.

The best control over the roasting process can be obtained by using a coffee bean roaster that has been built specifically for that use, rather than a re-purposed popcorn popper or frying pan. If you use a hot air roaster, you'll be able to roast a small quantity of beans in about 10 minutes. A drum roaster can produce a larger quantity of roasted beans per batch, but will take a bit longer. Keep in mind that roasted coffee beans begin to go stale much more quickly than unroasted beans, so a small capacity roaster is not necessarily a bad thing. As a rule of thumb, you can figure that 2.5 ounces of unroasted beans will ultimately make about 15 to 20 cups of coffee.

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