The Roast

The roast is all about getting to the first crack.  Charging the machine is  the term used for dropping beans into a pre-heated roaster. The beans will go through endothermic and exothermic reactions throughout the roast. The roasting stages and smells indicate where you are in the roast. First, the green bean will transition to yellow; now the bean has a hay like smell. When the Maillard effect  browns the bean, the smell changes again, and reminds me of baking scones. Shortly after caramelisation occurs, now the caramel notes are developing. Care must be taken to control the temperature, gas, and airflow through to first crack. First crack is the point at which steam and carbon dioxide are released, caused by the breaking down of sugars and amino acids. First crack is called after hearing more than three outliner cracks. We are at the  light to medium stages of the roast. Some beans merge into second crack straight away. This sounds quieter than first crack, not dissimilar to a bowl of Rice Krispies.  Coffee beans must not be taken beyond second crack. Over-roasting the bean will leave it tasting bitter and burnt. The roaster  profiles the beans throughout roasting, removing beans at intervals to cup,  and deciding at which point the bean tastes best. Coffee roasters these days use coffee roasting software which produces an x, y, axis graph showing the rate of rise of the bean, allowing previous profiles and roasts to be emulated.

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