With the traditional roasting-process, coffee is brought to a temperature of about 200-240 °C; the process lasts 18-20 minutes. In this time coffee beans undergo a series of chemical and physical changes.
First of all there’s a significant reduction in weight (about 20%), mainly due to the evaporation of water.

Besides, due to the release of “heavy” gasses inside the coffee, as carbon dioxide, the volume increases by about 60%, making inflate the single grain and his color goes from green to brown. According to the temperature , the roasting level changes, and so the grain’s color. During the roasting process, the coffee frees part of its volatile aroms, releasing its characteristic wonderful fragrance.