EVALUATION OF THE TOTAL ANTIOXIDANT ACTIVITY AS A MARKER OF THE DETERIORATION OF APPLE JUICE OIL STORAGE

The total antioxidant-activity (TAA) has been evaluated as a marker of the deterioration of apple juice during storage. Unfortified juice, j uice fortified with vitamin C, and an apple ''drink'' (6% juice), to w hich vitamin C (300 ppm) is added during manufacture, were evaluated. Vitamin C activity represented a minor fraction of the TAA (ca. 1%) of ''longlife'' apple juice, with chlorogenic acid and phloretin glycosi des as the major identifiable antioxidants (ca. 32% and 11% of the TAA , respectively). Antioxidant activity ascribable to these substances w as stable under the storage conditions examined, whereas ascorbic acid added into the juice was unstable; in fortified whole apple juice the TAA value correlated significantly with the decline in the ascorbic a cid concentration, while in the apple drink there was a direct relatio nship between TAA and ascorbate.