While you can finely grind any origin coffee and brew it for an espresso, it is widely accepted that Single Origin coffee when brewed for espresso will provide too overpowering taste and flavour. In order to make an espresso smooth and mellow a range of Single Origin coffee beans are blended, thereby balancing the individual tastes of the origins to produce one rounded and smooth blend.
While good blends can be made with 100% Arabica coffee origins, often a small portion of Robusta origin coffee is added to boost Crema and Also increase the Caffeine content. Arabica coffee is hard to grow and prefers high mountain slopes making it very difficult to cultivate. In contrast Robusta grows readily at low altitudes and has increased protection from disease due to it's greater Caffeine content.
While Robusta is easily classified as a poorer substitue to Arabica, it's importance in blends remains significant, and most Pennine Topa De Coda espresso blends still use a small portion of Robusta in the Traditional Italian blending style. Pure Arabica espresso still produces some wonderful, rich shots with bright flavours, the difference can be subtle and if you are unsure what will suit your needs ask to try samples of both 100% Arabica espresso blends and Blends incorporating a little Robusta.