In order to be able to consume coffee beans, first the beans must be roasted. Before they are roasted, coffee beans are green and small. By roasting them, they expand and, during this process, the color, smell, and taste of the coffee beans change. After roasting, the coffee beans can quickly lose their freshness so the roasting process is normally done soon before they are meant to be consumed.

The process of roasting coffee beans begins by sorting the beans out from the other debris that might get mixed in with them during the picking and opening process. This can either be done by hand or with a machine called a hopper. The beans can then be put into the roaster.

Roasters are usually metal drums that are positioned horizontally. They then rotate, circulating the beans over a heat source below the drum. This heat source can be anything from natural gas to petroleum gas, to wood. Roasters normally run on temperatures upwards of 400 degrees, though different varieties of beans differ on their ideal roasting temperature. They are roasted for up to thirty minutes.

The different levels of roast - from light roast to double roast - depend on how long and how hot the beans are roasted. For the light roast, the beans are only roasted long enough for them to pop and expand in size once. To roast the beans to the darkest level, double roast, they must be cooked longer and hotter, until they begin to smoke and carbonize.

After the beans are roasted, they are air-cooled. Coffee beans that are roasted release a lot of carbon dioxide while they are cooling, so they must be left out to cool before they are packaged. Once they are cooled completely, then they can be packaged - light-resistant bags are best.

Some people prefer to roast and grind their own coffee at home. For hundreds of years, people have been doing this, by using fire coals or iron pans, or by improvising and using a regular cooking oven or popcorn popper. In fact, before the 1900s, commercial coffee roasting companies did not exist and everyone who wanted to enjoy a cup of coffee at home had to roast their own beans.

Roasted coffee beans stay fresh for about a month as long as they are not ground. Ground coffee beans should be used immediately to avoid losing freshness.