They are primarily meant to classify antioxidants in relation to each other, pure molecules or extracts that can be selected later for an application.

Simplified systems are chosen:

• either because they mimic a mode of action that is likely to be used by the antioxidant (e.g. antiradical mechanism or metal chelation);
• or because they mimic a medium representative of a food system in which oxidation reactions can be easily accelerated to achieve in a few hours or days a result on the effectiveness of the antioxidant (e.g. liquid emulsion).

There is no “reference” test in this domain, but among the existing tests, one in particular is used in a great number of studies, thus allowing to perform comparative studies to be carried out. That is the DPPH° TEST, which provides information on the antiradical activity of compounds.

They are carried out:

• either under usual conditions of use and conservation of products (food, cosmetics, biomaterials…);
• or under accelerated aging conditions, which involve forced oxygenation, a higher temperature or increased exposure to light…

These tests are rather hard to perform and require the monitoring of the oxidation state of the products for several weeks to several months. They usually require an extraction of the fat to analyze oxidation markers (e.g. hydroperoxides, see the “analysis of dietary fats” sheet).