Deriving a global antioxidant score for commercial juices by multivariate graphical and scoring techniques: applications to blackcurrant juice

Blackcurrants constitute an important source of potential health promoting phytochemicals (e.g. phenolic compounds, ascorbic acid) due to their antioxidant properties. Only small portions of berries are consumed fresh, most of their intake coming from processed foods, such as juices. Seven techniques were used to measure antioxidant capacity and antioxidant compounds of 10 juices. This yielded a large disparity of results. No single test, even the most popular ORAC assay, is able to compare the antioxidant capacity of similar food matrix such as blackcurrant juices. By combining tests from a large battery of « antioxidant » assays, it is possible to improve the discrimination of a food matrix by establishing a Global Antioxidant Score (GAS) which correlates well with graphical representations like Chernoff faces or stars. The latter approaches may help food industry managers and authorities to compare their « antioxidant » products with those existing on the market.