Roasting Basics: "what is roasting"
Roasting coffee has a mystique factor. Plainly explained, it is a process by which green coffee beans are finished for consumption. This is done using either convection or heated air in which, by controlling the chemical processes caused by such heating, the aromatics, acids and other flavor components are expressed. These flavors are balanced in such a fashion that you augment the natural qualities and flavors; the acidity, the aftertaste and body of the coffee to the levels desired. In essence, roasting should be done in a way that maximizes the potential, the expression of the green coffee beans and the resulting beverage qualities.
~ Warning! Extremely boring! ~
Want more? Ok.
A Primer for Coffee Addicts & Anal Compulsives.
Great coffee roasting is actually a complicated physical and chemical process induced by the heating of the green coffee beans. The first stage is endothermic, meaning "a reaction which occurs with the absorption of heat". In this process the green coffee beans are slowly heat dried to become a yellow color and the beans begin to smell like toast or popcorn. Next the roasted bean begins what is referred to by roasters as the "first crack", or the first exothermic reaction, meaning "release of heat". At this point violent popcorn like reaction occurs to the coffee bean. This occurs at approximately 205 °C (400 °F), at which point the bean doubles in size and the color becomes a light brown tone, and the bean experiences a weight loss of approximately 5% - 8%.
As the temperature rises from 205 °C to approximately 220 °C (401 f - 428 f), the next stage occurs, in which the color changes from light brown to medium brown, and a weight loss of approximately 13% occurs . The resulting chemical process is called "pyrolysis", meaning "change or decomposition in chemical structure due to heat", and is characterized by a change in the chemical composition of the bean as well as a release of CO2 . At this point the coffee beans have lost about 20% of their weight and have doubled their volume. This loss is reflected in the prices we as roasters have to charge. After all a pound of green coffee only makes about 12 ounces of roasted coffee. The only true "inexpensive" coffees are old coffees, seconds, and old roasts. So if someone sells you coffee for a bargain, maybe you are not getting what you think!
After the pyrolysis, another short endothermic period ensues which is followed by another exothermic step called the "second crack". This second pyrolysis occurs between 225-230°C (437 f - 446 f), and the roast color is defined as medium-dark brown. The second crack or pop is much quicker sounding and the beans then quickly start to take on an oily sheen. It is in these final stages that a master roaster must determine what roast best serves his bean's potential. It is here that his craft ability meets with his customers tastes. For example, an espresso potential is maximized in roasting when you maximize the sweetness and aroma of the coffee while minimizing the bitterness and acidity. Most roasters focus on the latter and therefore roast extremely dark, yet when they do they diminish the sweetness and aroma. leaving the coffee flat, a no note tune. Basically in my humble opinion, unpalatable!
This occurs primarily with roasters who cater to the unknowledgeable demands of the restaurant clients, without insisting that they offer a truly flavorful coffee as opposed to the burnt and bland flavors of most espresso roasts. The result reminds you of your coffee house daily swill or what most coffee houses use and sell for use in iced coffee! Even here in Nashville the majority of establishments brag about their dark, burnt and flavorless expressions they pass for coffee. Espressos can be made right, but if they are roasted until they "bleed" their oils, then they are no longer drinkable, except in blended beverages. This explains why there is a preference and a popularity for espresso based drinks, where either milk or other flavors are used to replace the sweetness that was lost by roasting darkly to the level of a straight espresso, and no real demand for the espresso shot itself.
A Visual Coffe Roast Guide
1-7: The coffee is simply too green
8-10: Nice Breakfast Roast
11-12: Target RoastGood Body, Best Balnce.
13: Good Dessert Roast, nice tones for sweets.
14-16: COFFEE DOA!! But Sold Everywhere!
Except at BC Beanery!
