Introduction
Most foods contain some antioxidants. The total amount of antioxidant in a food can be measured by chemical means. At this site the Total Antioxidant Capacity (TAC) is expressed per 100 g (about 3.5 ounces) of food (go to Discussion link below). The units used to measure ORAC values [TAC = L-ORAC + H-ORAC] are micromoles Trolox equivalents. There are however, conflicting analytical data, derived by different methods, which are only relevant when used comparatively within the batch. Even methods described as using the same chemical analytical procedure are being modified to improve the sample extraction and cleanup, and therefore the results cannot be correlated with earlier reports.
go to Discussion
TAC is a useful quantitative analytical measure of antioxidant content, but it lumps together the good, the bad and the positively harmful compounds loosely classed as antioxidants.

Comments
1. The "super foods" listed here, i.e. those exceeding 100,000 TAC units per 100 g food, will most likely include rosemary and thyme when measurements are made. It is important to emphasise that the herbs and spices, although very high in TAC units, are normally consumed in gram quantities rather than the 100 g values used in the listing.
2. An alternative analytical method of ranking antioxidant-containing foods is noted. An assay for the total concentration of redox-active compounds was used to analyse over 1000 US foods (supplied by USDA National Food and Nutrient Analysis Program) and the top twelve foods were blackberries, walnuts, strawberries, artichokes, cranberries, brewed coffee, raspberries, pecans, blueberries, ground cloves, grape juice, and unsweetened baking chocolate (Ref. 7). While these foods are mainly recognised as good sources of antioxidants using the method referenced (1-6) below, the ranking order is different.