How to Achieve Quality and Safety in Coffee Roasting

Many of us start our days on an early schedule, and morning routines can vary from one person to the next. Some like to start by exercising before heading off to work, while others may choose to sleep until the last minute. Morning activities vary, but a morning beverage is common for most. One of those go-to selections is coffee. While choosing coffee sounds simple, the process of producing coffee can be complicated.

Think about a trip to the grocery store to view the coffee choices available. You might see options such as light roast or dark roast, flavors such as French vanilla or cinnamon, and even a difference in the amount of caffeine. Some like to brew coffee at home, and others choose to hit the local coffee shop for a medium-sized, light-flavored coffee with steamed almond milk and a package of sweetener. While these choices are based on individual preferences, the path that coffee takes to get from raw beans to grocery store shelves or to a coffee shop is similar: The beans must be roasted to get to the final product.

Coffee roasting starts with green coffee beans, which are processed to change the properties of the bean. The roasting process is what defines the aroma and flavor. To achieve the desired product, a coffee roaster must decide on the type of coffee they will produce (i.e., light, medium, or dark roast), which will dictate the roasting method. Most of the traditional methods rely upon drum roasting, which uses gas burners to heat the air. This method requires a coffee roaster who not only has a good eye for bean quality but also has a fundamental understanding of the proper gas mixture for the process. While the gas burner method is proven, it can be labor intensive and present safety concerns. Another option for drum roasting would be incorporating electric heaters.

The method of electric heating has evolved over time. In the beginning, electric heaters struggled in various stages of the process to produce the desired results for both the roaster and the consumer. Other types of heaters that were used during the drum roasting process were the open heating coil or heating rods. While the installation and operation were easy, the heaters could not deliver efficient temperatures, desired batch volume, and consistent quality compared to gas roasters.

With improvements made through R&D, along with improved materials, a new generation of electric heaters have been implemented in roasting machines and are achieving similar results to gas-powered roasters. Innovations such as ceramic heating elements, paired with an actively controlled blower, allow roasters to achieve temperatures up to 1,100°F, which can be controlled in a precise manner. This results in higher quality coffee, which can be roasted continuously and precisely to build and support a strong brand image.

Drum Roasting

Coffee roasting can be accomplished in various machines such as packed bed and centrifugal roasters. One of the more common types of roasters on the market is the drum roaster. This type of machine consists of rotating drums that tumble the beans in a heated environment. Heat can be applied indirectly to the drum or, in some cases, the roaster uses direct fire, a process in which the heat is applied to the product inside the drum. The heat for the process can be supplied by natural gas, wood, or electricity.

Drum roasters are segmented according to their batch size (kg of beans per roasting batch). Industrial roasting machines, which process batches of more than one ton per pass, range in power from 50 kW to 1.4 MW. They roast for popular coffee brands and are installed in an industrial environment where safety and sustainability are constant areas of improvement. The very small sample or laboratory roasters are used by industrial roasters to create their roasting programs to refine the process. Lab roasters can operate at up to a few kW.