The aromatic properties of coffee are released by the high temperatures reached by roasting. Temperatures are raised progressively to 440 ° Fahrenheit (230 ° Centigrade). This releases steam, carbon monoxide, carbon dioxide and other volatiles, resulting in a weight loss of 14 - 20%. Released gases increase the beans' volume from 30 - 100%.

The color of the beans changes to a deep rich brown; their texture becomes porous. The most important result of roasting is the appearance of the characteristic aroma of roasted coffee, which comes from complex chemical changes in the beans. After roasting, the coffee is quickly cooled to safeguard the newly created aromatic, ethereal oils.

Sorting
Good-quality coffees are sorted by electronic sorters to remove any substandard beans.

Grinding
Coffees can be left as whole beans and sold as vacuum packed coffee to be ground by the consumer at home or ground by the roaster before packaging.
Packaging
The aromatic oils set free by the roasting process have a relatively short life and oxidize (get rancid) easily. Roasted coffee ages quickly and loses its aromatic qualities if it is not stored in a cool place in an air tight container. Effective packaging therefore is essential to prevent air (oxygen) getting to the freshly roasted coffee.

Coffees sold as whole beans should be packed in an air-tight bag, with a one way valve, in which the air has been exchanged for an inert gas (nitrogen). The one way valve lets coffee gasses escape but prevents oxygen from the air entering and causing the coffee's aromatic oils becoming rancid.

Modern packaging materials like plastic films and a combination of aluminum and cellulose conserve coffee well over the medium term. The most satisfactory way is packaging under vacuum or in an inert gas, using perfectly impervious materials. Julius Meinl packages its blends using either the vacuum or inert gas method, thus keeping the coffees always fresh and flavorful for you to enjoy.