What Happens to Coffee Beans During the Roasting Process?

The coffee roasting process is what most influences the taste of that cup of coffee. When the coffee bean roasts it starts to change. As the heat is applied, the carbohydrates and fats change into aromatic oils. The coffee flavor comes out when the moisture and carbon dioxide starts to burn off. The longer the beans are roasted the more they change. The general rule of thumb is the quicker the roast, the better the coffee. There is no universal standard for roasting coffee. It is part “art”. The coffee roasts between 240 and 275 degrees Celsius for a duration of between 3 and 30 minutes, depending on the desired aroma. The roasting process does not affect the caffeine level of the coffee.

There are many different types of coffee roasts.

Light Roasts are light brown in color. This roast is for milder coffee varieties. There is no oil on the surface of these beans, because they are not roasted long enough to bring out the oil. They are known by these names:

  • Light City
  • Half City
  • Cinnamon
  • New England

Medium Roasts are medium light brown in color. This roast has a stronger flavor, and a non-oily surface. This roast is preferred in the Eastern United States. They are known by these names:

  • City
  • American
  • Breakfast

Medium-Dark Roasts are a rich, dark color with some oil on the surface and with a slight bittersweet aftertaste. This roast is preferred in the Western United States. They are known by these names:

  • Full City
  • Light French
  • Viennese (preferred roast in the Pacific northwest of the United States)

Dark Roasts are shiny black beans with an oily surface and a definite bitterness. The darker the roast, the less acidic taste will be found in the coffee. Dark roast coffees run from slightly dark to charred and these are some of the names of the dark roasts. This roast is preferred in France and Italy and is not very popular in the United States. They are known by these names:

  • High
  • Continental
  • New Orleans
  • European
  • Espresso
  • Viennese
  • Italian
  • French
  • Spanish

After roasting coffee, the coffee beans are sprayed with water to cool them. Then they are transferred to another hopper, where the coffee beans are brought to room temperature and the water is removed. The beans need to sit for between 12 and 72 hours until they have stabilized and dried. Then the coffee beans are ready to be vacuum sealed for the market.

In conclusion, coffee beans change in color from green to gold to brown to dark brown with some oil, to very dark brown and more oil, then to almost black and very oily. They also double in size releasing the wonderful flavor compounds that make good coffee. Coffee beans lose about 15 percent of its green weight during the roasting process. There are over 800 compounds found in fresh roasted coffee. So that wonderful cup of coffee we enjoy is a very complex beverage.



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