There are two major varieties of the coffee plant: Arabica and robusta. All the best tasting coffee, imbued with rich, subtle flavor, is made from arabica beans. Harsher and more bitter coffees are brewed from robusta beans. The only reason robusta varieties are used at all is that they are hardier plants and cheaper to grow and harvest.
Robusta coffee plants survive better than arabica coffee plants because robusta beans produce and contain about twice the amount of caffeine as arabica beans. Because caffeine is a powerful insecticide and anti-microbial agent, the extra caffeine helps protect the robusta coffee plants from pests.
A recent Consumer Reports study demonstrated that a 12 ounce cup Starbucks coffee contains nearly twice the caffeine content of an equal size cup of Dunkin’ Donuts coffee. So, it would appear that the coffee beans Starbucks uses have twice the caffeine as the coffee beans Dunkin’ Donuts uses. Now, it is a fact that no arabica beans have nearly twice the caffeine content of any other arabica beans. So, figure it out for yourself. Starbucks claims to use arabica beans. But the evidence of the caffeine content of its coffee puts the truth of that boast into considerable doubt!
Of course, Dunkin’ Donuts uses a medium roast, which brings out the full flavor of its coffee. Starbucks burns its beans, rendering them so uniformly bitter that it impossible to guess their humble origin by tasting. Is it any wonder that Dunkin’ Donuts consistently tops the list of blind taste tests and Starbucks invariably falls to the bottom?
In case anybody needs any more proof that Starbucks uses cheap junk robusta beans, you can be sure just because their coffee has twice the caffeine of McDonald’s. The CSPI study showed that Starbucks coffee has 20mg of caffeine per ounce, compared with McDonald’s that has only 8mg per ounce! See http://www.foodbeast.com/news/coffee-visuals/