Behind the Scenes · The Coffee Journal
Artisanal Roasting
How the green bean becomes coffee. Between 200 and 230 degrees, the green bean transforms. In minutes, complex chemical reactions create the hundreds of aromas that make up the coffee you drink every morning.
Alchemy
The Magic of Heat
Roasting is one of the most complex food transformations. A bean that smells of grass and earth becomes, in minutes, an extraordinarily aromatic beverage.
From Green Bean to Cup
The green bean contains aromatic precursors in the form of sugars, amino acids, and organic acids. Heat triggers chemical reactions: caramelization of sugars, Maillard reaction between sugars and proteins, and thermal degradation of acids. These three simultaneous processes create the 800 to 1000 aromatic compounds of roasted coffee.
It is the roaster's art to master these reactions: increase heat too fast, and the coffee burns on the surface before developing inside. Too slow, and aromas evaporate without forming. Balance is a matter of degrees and seconds.
The Reactions
The Chemistry of Coffee
Three major chemical reactions occur simultaneously during roasting. Each contributes differently to the final profile.
Color and Complexity
Reducing sugars react with amino acids to create hundreds of complex aromatic molecules. This reaction gives coffee its golden-brown color and aromas of toasted bread, hazelnut, and caramel.
Sweetness and Depth
Sugars break down under heat to form caramelized molecules responsible for sweetness and dark color. A longer roast enhances these caramel notes at the expense of fruity acidity.
Balanced Acidity
The organic acids present in the green bean (chlorogenic acid, citric acid, malic acid) gradually break down with heat. A short roast preserves the fruity acidity of the bean. A long roast reduces it and reveals body and bitterness.
The Levels
From light to dark
Roasting levels define the fundamental character of a coffee. From light roast that preserves fruity freshness to dark roast that reveals power and body.
Light Roasting (Light)
The bean stops just after the first crack. The floral and fruity aromas of the origin are preserved. The acidity is bright, the body is light. The preferred roast for specialty coffees and filter.
Medium Roast
Between the two cracks. The perfect balance: fruity acidity has integrated, body has developed, caramel and hazelnut notes emerge. The roasting for specialty espresso and Carrera Café.
The Machines
The Master’s Tool
The artisanal roaster works with precise machines that allow control of every parameter of the roasting curve.
The Rotating Drum
The reference machine for artisanal roasting. The beans rotate in a heated drum, ensuring even exposure to heat. The roaster controls the heat source (gas, electricity), drum speed, and airflow through a precise digital interface. Each batch is recorded on a real-time temperature profile.
The Artisan
Human Expertise
The machine doesn’t do everything. The roaster interprets the data, adjusts the profile in real time, and makes choices no algorithm can anticipate. It is a full-fledged craft.
The Ear and the Nose
An experienced roaster works as much with his instruments as with his senses. The first crack sounds like popping corn. The aroma evolves from grass to hazelnut to burnt. The color of the bean provides valuable visual clues.
It is this dialogue between numerical data and sensory perceptions that defines the artisan. Each different coffee batch requires a subtle adaptation of the profile. It is a learning process that never ends.
At Our Place
Géogène Roasting
At Carrera Café, we trust Géogène, a Quebec artisanal roaster, to transform selected green beans into exceptional coffees that we serve you at Petit-Champlain.
Géogène · Specialty Roaster
Géogène roasts our coffees in small batches in Quebec, precisely controlling every roasting parameter. Their artisanal approach guarantees maximum freshness and exceptionally precise flavor profiles. We receive our batches just a few days after roasting, never more.
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