Analysis of Coffee roasting steps

Once the coffee seed is planted, no one can change its final quality. However, the color, aroma, bioactive components and health characteristics of coffee are related to the roasting process. In the process of roasting, coffee is heated at 190-220 °for 7-20 minutes, which helps to bake out its aroma and good taste. It also helps to form lactone, nicotinic acid, coffee tannic acid with antioxidant effect, caffeine and other health-beneficial compounds and trace elements.

Caffeine is the only substance that remains unchanged throughout the baking process, but huge, complex and not yet fully understood chemical changes in coffee beans cause about 25% of their weight loss. During the baking process, the color of coffee beans changes from green to yellow, then to brown, and finally to brown. The process from yellow to brown is often referred to as the first burst, because a popcorn-like popcorn popping sound occurs at about 160 degrees, when the coffee beans more than double in size, turn light brown, and lose about 5% of their weight. The coffee bean expands to 150% of its original volume, and caramelization begins inside the bean.

Next, the temperature rises from 205 °to about 220 °, the color of the coffee changes from light brown to medium brown, and there is about 15% weightlessness. This chemical process is called high-temperature decomposition, in which the chemical composition of coffee beans changes and releases carbon dioxide. After the first burst, there is a pause, followed by a brief endothermic process, followed by a chemical reaction, followed by an exothermic process known as the second burst. The second high temperature decomposition occurs at 225 °and the color changes to a moderate black-brown color.

The second burst is faster, and the coffee beans show an oily luster and become fragile, and at this stage, its ingredients begin to carbonize, resulting in charred properties. The smell of coffee can be smelled before the first burst. The first burst reflects the physical stretch of coffee and the chemical reactions of the compounds associated with it, such as the formation of water and the release of carbon dioxide. When the temperature reaches its peak, a second burst occurs, when the cellulose, matrix and coffee beans all begin to break.

The darker the robusta beans are baked, the more delicious they are; the darker the Arabica beans are baked, the more delicious and special they lose. On the other hand, medium baking can make their delicacies well displayed.

The automatic sorting machine separates high-quality coffee beans from many coffee beans, removes beans that are too light or too black, and applies very sophisticated production control techniques to reduce the percentage of unqualified coffee beans, including: ultraviolet fluorescence analyzer, identify moldy beans; trichromatic light mapping technology produces color fingerprints (yellow-green, red and infrared) for each coffee bean.

Soluble coffee needs vacuum packaging because it has strong water absorption. In roasted coffee, soluble coffee does not contain a lot of volatile substances, and most soluble coffee is made from robusta coffee. Robusta coffee is cheaper and contains more caffeine than Arabica coffee.