Raw coffee beans are actually green seeds that contain carbohydrates, water, proteins, lipids, acids, and alkaloids. Green coffee tastes and smells like peas and features a hard covering. Green beans should be roasted. The high-temperature processing allows us to alter the bean structure and its biochemistry and makes it fit for consumption. Similar to my opinion that grinding coffee beans with improvised means is useless, I don’t believe that they can be properly roasted at home. Folks, there are educated professionals who acquire specialty equipment and are hipped on this subject. Do you think you’ll be able to properly roast coffee beans using utensils on hand like a frying pan?
How Is the Process of Coffee Beans Roasting Going On?
The process of roasting is required to bring coffee beans to the condition suitable for consumption, to make them as tasty as possible, and unleash their maximum potential.
The process takes place in a roaster, which is a kind of oven that transfers heat to the beans by convection, conduction, and radiation.
There are 2 main types of roasters. The operation principle of the first type of such devices is to roast beans in a pseudo-fluidized bed, mainly due to convection. The method of operation of other roasters is based on heat transfer due to thermal conduction of the drums. These are 2 different methods, and both of them are good for roasting beans. This is the case when a coffee chef rather than the equipment is a key player.
Due to the roasting process, countless chemical changes take place in coffee beans, with thousands of compounds being created and broken down. Green coffee is loaded into the heated roasting chamber and undergoes drying as the first stage of the roasting cycle. During the first few minutes, the beans desiccate most intensively, and chlorophyll causes them to change color from green to yellow. Afterward, elevated temperatures cause a chemical reaction between amino acids and sugars, known as the Maillard reaction. We often encounter it in our everyday life when we fry meat, bake bread, or cook condensed milk.
After 75-80% of the total roasting time, you’ll hear the first “crack” (it’s a professional term), which is similar to popcorn popping sounds. The cracking occurs because the moisture inside the beans heats up, expands, and comes out, destroying the bean structure. Due to the caramelization of sugars, the beans get their distinctive brown color. If you continue roasting, you’ll bring the beans to the second “crack,” which occurs due to the burning of sugars and cell walls. In this case, the color of the beans will be closer to black because of oils that will appear on their surface. The last step is to cool the beans to stop all processes going inside.
During the roasting process, green coffee beans undergo multiple changes, both internal and external. For example, their color turns from green to brown, and they become lightweight due to the moisture loss. Their density decreases, making the beans fragile, but at the same time, they almost double in size. In addition, a lot of aromatic compounds are produced inside the beans.
When you know how difficult the process of coffee roasting is, you can realize that it is impossible to control it at home. I have no supporting arguments that will convince me to roast them on my own.