The coffee roasting phases

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 approximately 210°-220°C and the complete process takes approximately 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 specifically designed, blend by blend, and controlled using a sophisticated computerized method.

The different roasting phases are:

  • 50° C begins changes to the internal tissue of the bean
  • 60°/70° C start of evaporation
  • 150°/180° C start of “light roast” stage
  • 210°/220° C optimal level of roasting

Roasted or toasted coffee has a characteristic bitter taste and increases its solubility in water; it therefore becomes more friable, more easily reduced to powder and therefore more suitable for infusion.

A lighter roast tends to reduce the "too bitter" defect of the coffee and, possibly, to enhance the qualities of acidity and sweetness; in a darker blend, the flavors in the cup tend to flatten. In this regard, we advise you to be wary of color mixtures that are too dark - in this case the manufacturer has evidently preferred to favor the flattening of defects rather than exalting their merits.

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It is worth remembering that during the roasting process the substances making up coffee undergo chemical transformations. Like, for example, the color change linked to the caramelization of sugars, the carbonization of cellulose and the formation of volatile compounds which is due to the particular aroma of roasted coffee .

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 increase by up to 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 espresso blends and enhancing all the organoleptic properties of the product.

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Immediately after roasting, the degree of color of the mixture is checked with a special laboratory instrument. This information, to guarantee optimal 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 phases. Furthermore, after cooling, the freshly toasted mixture 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/stabilization phase) the product is destined to be packaged in grains will be sent, in the shortest possible time, to packaging, while the product destined to be ground will be sent to the grinding groups.