There are many stages involved in the production of coffee. One of the last things that needs to be done is called roasting. The way a coffee bean is roasted is perhaps the most important things that can affect its flavor later on.

It's the roasting process that takes a processed bean and changes its chemical compound as well as physical properties into something that can be commercially sold. While an unroasted coffee bean contains much of the same characteristics of roasted beans, including some of the acids and the caffeine, the unroasted bean lacks the most important quality: a favored taste.

Coffee has been drunk for hundreds of years, most likely since the fifth or sixth century of the Common Era. For most of that time, and until the twentieth century, the process of roasting coffee was something people did for themselves at home, or in restaurants where it would be served.

Even during this period there were many variations of how the green coffee beans were roasted. Sometimes small quantities of beans were roasted in a pan, and other times they were held out over burning coals. Later, rotating drums were introduced which would turn the beans while being placed on hot coals.

Today, many people still enjoy roasting beans themselves and higher end coffee shops will also have their own methods for roasting. Traditional methods are still used, but more high tech options exist such as computerized heating drums. Some methods actually employ popcorn poppers.

The twentieth century however brought with it mass industry and this is why most coffee drunk today is roasted by heavy machinery in mass quantities. In these cases the roasting process is left as a mere part in a whole string of other processes which include sorting, cooling and packaging.

Industrial roasters can operate at a temperature as low as 370 degrees Fahrenheit and as high as 540 degrees. That's 282 degrees Celsius, or nearly three times the boiling point of water.

For the most part, industrial roasters are large rotating drums that turn and tumble the beans while they are heated by one of several different methods. The heat may come from burning gases, wood or electricity. Some of these processes are known as direct-fired, in which the beans actually come in contact with the flame.

The alternative is an indirect-fired process in which the beans aren't touched by a flame, though they still contact combustion gases.

These mass batches of coffee beans can be roasted anywhere from ten minutes to a half hour. The length of time any given bean is roasted will affect its final color and flavor.

It's the beans with lighter roasts, less roasting time, that maintain more of their original flavors. This is popular with beans from certain regions like Java so that the regions signature flavor will let it stand out from the rest.

Before a bean is roasted it is known as green, and green coffee is much more stable. That means that unroasted beans can last for a long time without going bad. Because of this, the roasting process takes place closer to where the final product will be sold, allowing for the freshest possible coffee to reach the consumer.