Natural antioxidants of foods. Some evaluations of analytical and methodological aspects

Free radicals and antioxidants are widely discussed in the clinical and nutritional literature. Antioxidants are needed to prevent the formation and oppose the actions of radicals and reactive oxygen species. The activity of natural antioxidants can be related to their concentrations in food and to factors (such as food composition, presence of synergic substances, temperature, etc.) which contribute to the final antioxidant status in the food items. The classification of natural components with antioxidant properties is still poorly defined, since nutritional characteristics of several antioxidants (i.e. tocopherols, phospholipids, aminoacid-amines, etc.) are more important than their antioxidant action. The analytical methods for the evaluation of antioxidant amounts should be considered together with the determination of antioxidant properties in defined Food. Methods for evaluation of the amounts of antioxidants and the relative antioxidant power are reviewed.