I guess to extend Len's explanation a little further- robusta has a very narrow taste/aroma spectrum. There are some minor exceptions to this rule, however generally a robusta grown and processed in Lampung, cups fairly similarly to a robusta from Vietnam, a robusta from Uganda and a robusta from India. Processing methods (washing- drying- polishing) at origin have some impact on the final quality of the bean- but really the differences are not huge.
On the other hand (using an Indonesian coffee example) Arabica from Aceh, vs Mandehling, vs Java, vs Toraja, vs Irian Jaya are all hugely different in their cupping profiles.
Arabica has twice the chromosomes of Robusta- and the species (and various sub-species and hybrids) develop characteristics from soil types, altitude. sunlight hours, rainfall/percipitation, chemical balance in the soil as well as the processing techniques as above.
Len is indeed correct- just because its Arabica does not necessarily mean it will roast well and cup well!
I think that roasters saying you must have robusta in an espresso blend is very outdated. Robusta tends to hold its flavour longer than arabica once roasted which has appeal to those distributing stale coffee. As I was once told, if you have a question, try it and draw your own conclusion.
so is this what charbucks does? I haven't been able to figure out how coffee roasted within an inch of it's life can contain any caffeine at all, let alone the amount that they claim it does. Are they going heavy on blending robusta in with their arabica's?
I think daddy Starbucks simply found that over-roasting their coffee gave it an "edge" that people would interpret as tasty... but my last pound of Starbucks was a bag of Sumatra that should have been really fine coffee, but it was so burnt I honesty threw the bag out after trying it twice. That's really bad. Never have wanted to buy from them again after that.
Trung Nguyen in Vietnam has done amazing things with Robusta both in selecting out a Culi Robusta that is superb and mixing it with other beans in their repetoire (Arabica, Chari, Catimor) to create coffees like the House Blend that are so multi-dimensional that people generally declare that they have never tasted anything like it before.
I still maintain that as wonderful as Arabica can get, it still is only one part of the flavor spectrum of coffee. You simply have to blend different varieties to get a truly orgasmic brew. Why not? I don't understand the rigidity on the topic. TN created about 6 different blends that really explore most of these possibilities
Nothing in their line is dark-roasted. I have always felt dark roasting was what people do to try to move beyond the flavor range of the coffee itself. What can be done though, is to mix that bean with another to create that wider spectrum without dark-roasting.
Unless you like charcoaled beans. Probably some people simply like burnt coffee, just like some people like Louisiana hot sauce.
As far as I know arabica is a higher quality of bean growing at higher altitudes than the hardier robusta. Since there's less bugs at higher altitudes to eat away at arabica it doesn't produce as much caffeine than lower altitude growing robusta to protect itself. I've read that arabica is less hardy than robusta and doesn't have as many yields.
I roast an Indian robusta to blend for espresso. It is a different bean than arabica. In the cup it does produce more crema but the taste is a bit stronger and the crema is foamier and less dense than arabica.