Why do coffee beans need to be roasted?
What does roasting do for the coffee?
I am thinking about juicing beans, to create a very strong cup of coffee, that does not have any burnt taste.
For this I believe that I should use un-roasted green coffee beans.
I have a lot of ignorance in this area though and need help and suggestions.
If you have ever tasted under-roasted (or even green) coffee, you would find that it has an extremely sour, acrid, flat, and unpleasant flavor.
During the roasting process, several chemical reactions (including the Maillard process, Strecker degredation, and caramelization) take place between the sugars and amino acids in the beans. These reactions are responsible for developing the flavors, aromatics, and sweetness within a coffee. Through extensive tasting, smelling (during and after the roast), and science, an excellent roaster should be able to find the best balance of flavors within a bean.
When coffee is initially tasted (before purchasing from the farm), it is always done so with a light roast. This amplifies the flavors of the beans themselves, but it also amplifies the defects. Many roasters will choose a darker roast in order to mask any of these defects and create their own consistent "signature roast" flavor. It is impossible for a large coffee company to achieve consistency between batches with a light roast – coffee is a seasonal crop and varies far too much, even from hillside to hillside on the very same farm. Even with the world’s best roasters, when consistency is more important than quality, the end product quality suffers.
If all the coffees you have tasted have a burnt taste, I would wager that you have never had the opportunity to taste exceptional coffee. If you are interested, I would recommend searching for local roasters on http://www.coffeegeek.com. Look for high quality coffees from farms who have won awards such as the Cup of Excellence. Look for a shop that advertises the roast date, not expiration date. Coffee is generally best between 4 and 10 days after roasting. Look for lighter roasted beans that do not appear black or show visible oils. Ask questions! A passionate roaster will be willing to tell you way more than you ever wanted to know about his or her coffee. Many smaller "third wave" coffee shops will focus on quality above all else, even if it means that the flavor of their coffee is constantly changing with the seasons and growing conditions.
By the way, you might have just opened Pandora’s box of coffee – enjoy your journey.