Determination of antioxidant properties of aromatic herbs, olives and fresh fruit using an enzymatic sensor.

The aim was to experimentally evaluate the antioxidant capacity of different fresh aromatic herbs (field balm, marjoram, parsley, rosemary, sage, sweet basil), several varieties of olives from Central Italy ('Carboncello', 'Rosciolo', 'Olivastro', 'Coratello', 'Leccino', 'Frantoio') and several types of fresh fruit (apple, apricot, banana, cherry, fig, grape, medlar, melon, peach, pear, pineapple, plum, water melon, yellow plum) using a superoxide dismutase (SOD) biosensor developed by the present authors. Measurements were carried out by comparing the biosensor response to the concentration of superoxide radical produced in solution using a xanthine/xanthine oxidase system in the presence and absence of the antioxidant sample considered. Tests carried out on different samples of fruit and aromatic herbs showed that the homogenised samples had better antioxidant properties than the centrifuged ones (obtained by centrifuging the homogenate), which sometimes gave extremely low antioxidant capacity values. The reliability of the proposed method was checked by comparing the trend of some experimental results found using the SOD biosensor with those reported in the literature obtained using the classic (ORAC) method. The precision of this method of analysis was found to be good for samples of aromatic herbs (RSD% <or=8%), acceptable for homogenised fruit samples (RSD% <or=13%) and less good for homogenised and centrifuged samples (RSD% <or=20%).