ORAC - Oxygen Radical Absorbance Capacity. ORAC is a method used by the USDA of measuring antioxidant capacities of different foods. The higher the ORAC, the stronger the antioxodant qualities of the food. Generally, the darker the pigment of a food or berry, the higher the ORAC value. This has a lot to do with the substance that gives pigmentation to foods - Anthocyanins, which are essentially nature's sun block, protecting the fruit from the harmful effects of the sun's ultra violet light. The ultra violet light encourages the development of free radicals which can cause oxidative issues and degeneration.
Acai berries are extremely rich in anthocyanins, with a corresponding rise in the acai orac score and it's antioxidant properties. As you can see the chart on the right, other popular fruits don’t even come close to the antioxidant power of the acai berry.