All you need is green (unroasted, raw) coffee beans
I know, you have probably never seen raw (green) coffee!
It was same for me five years ago, when for the first time I learned that the green coffee was even available on the market for home roasters. Today it is still not widely distributed and you are not able to find green coffee in your neighbourhood grocery store or even in bulk stores. Your only chance to find green coffee are online specialty coffee stores.
There are two main species of coffee trees:
- Arabica
- Canephora or as it is more popular: Robusta
Arabica beans are generally larger, longer and flatter than those of robusta and contain LESS CAFFEINE.
Arabica coffee is the oldest-known species and it’s grown on a high altitude, on mountainous plateaux or volcanic slopes (around 1000-2000 m), where there is enough rainfall (150-200 mm annually) and the mild days alternate with cool nights in a yearly average temperature range of about 15-24 °C. Arabica trees flower after a rainy season, and then require up to nine months for the fruit to mature. An Arabica tree may produce max 5 kg of fruit for a year, which after processing will come down to 1 kg of green coffee beans. Most of the world Arabica beans are wet-processed (washed).
Arabica coffee accounts for about 70 percent of the world’s coffee, but it is more difficult to grow, as it is more susceptible to diseases, pests and frost and therefore, more expensive.
Robusta coffee is very different: it is as robust in taste as it is in its resistance to diseases and pests, but its flavour is not desirable as that of arabica. Despite being cheaper, Robusta accounts for less than 30 percent of the world coffee production.
Robusta is mainly used in small percentage in blend, where appreciated for its full body.
U Roast 2 
Normally I do not learn article on blogs, however I would like to say that this write-up very forced me to take a look at and do so!