1. Field of the Invention
This invention relates to a roasting device and, more particularly, to a coffee bean roasting device for roasting small quantities of coffee beans in the convenience of a person's home.
2. Description of the Prior Art
Coffee beans develop color, taste, and smell during roasting. Roasting processes must produce consistent bean roasts for a wide variety of desired bean flavors. If the beans are not circulated evenly inside the roasting chamber, coffee beans will not roast evenly. Thus, even a skilled roast master has difficulty reproducing consistent coffee roasts from time to time.
There are two primary methods for roasting coffee beans. The first method is drum roasting. Drum roasting involves a technique similar to clothes drying. Unroasted or green coffee beans are placed in a round drum. Heating elements adjacent to the drum heat both the drum and the air inside of the drum. The heat from the inside wall of the drum is transferred to the coffee beans. As the coffee beans roll inside the drum, the coffee beans are heated and scorched, changing from a green state to a roasted condition. To generate darker roasts, the coffee beans are heated in the drum at a higher temperature or at the same temperature but for a longer time. U.S. Pat. No. 4,860,461 to Tamaki, et al., shows a drum roaster. In Tamaki, stirring and exposing the beans to radiant heat from infrared heaters adjacent to the drum roasts the beans in the drum.
The second method involves a fluid bed roaster that blows air up from the bottom end of a roasting chamber. The air raises the green coffee beans up on a bed of hot air causing the beans to circulate inside the chamber. U.S. Pat. No. 3,964,175 to Sivetz shows such a fluid bed coffee roasting system. In Sivetz, air is heated to a selected temperature that roasts the beans primarily by convection. The coffee beans are secondarily roasted by the conduction of heat from bean to bean and from the inside walls of the roasting chamber to the coffee beans.
Coffee bean roasting systems, such as those described in Tamaki and Sivetz, are very large complex machines. Thus, current roasting systems are usually operated in industrial locations. While large roasting machines may be suitable for the coffee roasting industry or for retail coffee shops that require roasting high volumes of coffee beans daily, they are ill-suited for home use that require smaller quantities of coffee beans. Moreover, few coffee lovers would tolerate a machine the size of a refrigerator taking up valuable kitchen space no matter how much they enjoy roasting their own coffee.
Existing roasting machines are also difficult to operate and expensive to maintain. Additionally, large roasting machines require custom equipment and include complex exhaust systems. Thus, coffee roasting systems are not feasible for ordinary home use. Finally, large coffee roasting machines are expensive.
Accordingly, a need remains for a home use coffee roasting device that evenly roasts a small quantity of coffee beans. A need also remains for a home use coffee roasting device that is simple, small, inexpensive, and easy to operate and maintain.