Robusta is a sturdy species of coffee bean with low acidity and high bitterness; it is used primarily in instant coffee, espresso, and as a filler in ground coffee blends. The bean comes from the Coffea robusta variety of the Coffea canephora plant (widely known itself by the synonym Coffea robusta) which has its origins in central and western sub-Saharan Africa. Robusta is easy to care for, has a greater crop yield, has almost double the amount of caffeine and more antioxidants, and is less susceptible to disease than arabica coffea. Roasted robusta beans produce a strong, full-bodied coffee with a distinctive, earthy flavour, but usually with more bitterness than arabica due to their high pyrazine content.