Roasting Coffee Beans: A Brief Description

One of the critical steps in drinking coffee is the roasting process. According to Wikipedia, roasting coffee transforms the chemical and physical properties of green coffee beans into roasted coffee products, which makes the coffee drinkable. When roasted, the green coffee beans are transformed into nearly double their original size, and changes in colour, taste, smell and density. Unroasted beans boast all of coffee's acids, protein and caffeine -- but none of its taste. Heat is required to initiate the chemical reactions that transform carbohydrates and fats into aromatic oils, as well as burning off moisture and carbon dioxide, breaking down and building up acids, and unlocking the characteristic coffee taste.

Because green coffee is more stable than roasted coffee, the roasting process usually takes place close to where it will be consumed. The vast majority of coffee is roasted on a large scale, but some die-hard coffee drinkers roast the coffee themselves in order to have more control over the freshness and roast level of the beans.

The coffee roasting process consists mainly of cleaning, roasting, cooling, grinding and packaging operations. In larger operations, bags of green coffee beans are hand or machine opened, dumped into a hopper and screened to remove debris. From the storage hopper, the green beans are conveyed to the roaster. Roasters typically operate at temperatures of between 370 and 540 degrees Fahrenheit for a period of time of anywhere between a few minutes to about half an hour. Roasters are typically horizontal rotating drums that are heated from below and tumble the green coffee beans in a current of hot gases.

We will be discussing more about coffee roasting in later blogs.