Contrary to popular belief, green, also known as white, grapes also contain antioxidants. A recent study that looked at the total antioxidant capacity, as measured by ORAC (oxygen radical absorbance capacity), of green grapes and red grapes found significant levels in each: The red grapes had an antioxidant capacity of 2016 while the green grapes had an antioxidant capacity of 1789.
The bottom line is that grapes of all colors contain antioxidants. It’s just that red and black grapes also contain anthocyanins, which are a type of phytonutrient responsible for red and blue pigment in fruits and vegetables.
Source: California Table Grape Commission