Anatomy of Roast Curve.

 Roast Curve.

Coffee Roasting:-

Coffee roasting is a process of transforming chemical and physical properties of green coffee beans into Roasted coffee beans. This process develops the aroma, flavors and other components in Coffee.

 

Physical changes during Roasting:-

• Change in color.
• Expand in size & volume
• Loos of moisture.
• Become brittle.
• Develops aroma & flavors.
• Change in density.

Moisture Content:-

Ideally green coffee must contain 10% to 11.5% of moisture. If moisture is too low, cup may taste like hay and woody. If moisture is too high, cup may taste like grassy and develops mold.

 

Phases of Roasting: -

Drying Phase/ Dehydration phase: -

 

Green beans have humidity of 10% to 11.5%. Hence in the first phase of roasting beans are soaked before the starting of actual roasting. Once the green beans moisture reaches below 5% the color of the beans starts to change from green to yellow. This happens once the temp reaches to 160 Celsius. Once the beans turn completely into yellow, its ready for the next phase.

 

Browning phase: -

This phase undergoes two major reactions, "Maillard reaction" & "Caramelization". Both of this reaction plays very important roles in Development of flavors & aromatic components. Once the moisture drops below 5%, degradation of amino acids, sugar, phenolic acids and lipids contributes to the development of Aromatics. And degradation of Chlorophyll causes green beans to change color from yellow to light brown. During this period beans starts to smell like toasted and hay. Maillard reaction is responsible for browning of beans and reduces sugar & amino acids, that reacts making hundreds of different aroma and color compounds known as "Mel aroids". whereas Caramelization helps to bring sweetness in coffee. During this phase Roasters slow down the speed of the roast to ensure the flavor development has occurred properly. In the end of browning stage, the coffee starts to pop's emitting all the energy it had observed from the beginning of roast. This is pops are known as 'First Carrack".

 

Development phase: -

The last phase of roasting is called the "The Development phase". From the beginning of the Drying phase, the beans start to observe energy and becomes exothermic and cracks. During Development phase beans starts to develop its essential aromatic components and flavor molecules.