To obtain the characteristic flavor and aroma of coffee, it is necessary to roast the green beans using special roasting machines. During the roasting phase, the coffee is exposed to a high temperature of around 210°-220°C and the complete process takes around 14-16 minutes. In this way, the green beans acquire the characteristic colors and unmistakable fragrances of roasted coffee.
The roasting phase develops through constant roasting curves specially designed, blend by blend, and controlled using a sophisticated computerized method.
The different toasting phases are:
- 50° C start of changes to the internal tissue of the grain
- 60°/70° C start of evaporation
- 150°/180° C start of the “light roast” stage
- 210°/220° C optimal degree of roasting
Roasted or roasted coffee has a characteristic bitter taste and increases its solubility in water; it therefore becomes more crumbly, more easily reduced to powder and therefore more suitable for infusion.
A lighter roast tends to reduce the coffee's "too bitter" defect and, possibly, to enhance its acidity and sweetness; in a darker blend, the flavors in the cup tend to flatten out. In this regard, we advise you to be wary of color blends that are too dark - in this case the manufacturer has evidently preferred to focus on flattening defects rather than enhancing their merits.
It is worth remembering that during the roasting process the substances making up coffee undergo chemical transformations. Like, for example, the change in colour linked to the caramelization of the sugars, the carbonization of the cellulose and the formation of volatile compounds to which the particular aroma of roasted coffee is due .
During cooking, the overall weight loss of the coffee can fluctuate from 15%-16% up to 20/21%, depending on the degree of roasting and is due to the elimination of the water contained in the green coffee . On the other hand, the volume of roasted beans can even increase by 50% compared to green coffee and the specific weight is significantly reduced.
We at Cellini Caffè have decided to use the traditional process of slow roasting, ideal for obtaining high quality express blends and enhancing all the organoleptic properties of the product.
Immediately after roasting, the degree of color of the blend is checked with a special laboratory instrument. This information, to guarantee the optimum quality standards, is carefully compared with the parameters established by the quality laboratory. In the presence of compliance with the established specifications, the mixture will be sent to the subsequent processing stages. Furthermore, after cooling, the freshly roasted blend undergoes a subsequent cleaning phase from any foreign bodies.
After roasting, each coffee blend is sorted into special silos from which, after a established rest period (degassing/stabilisation phase) the product is destined to be packaged in grains will be sent to packaging in the shortest possible time, while the product intended to be ground will be sent to the grinding units.