Changes of flavonoids, vitamin C and antioxidant capacity in minimally processed citrus segments and juices during storage

Citrus fruits of different species and cultivars, (Red blush grapefruit, Palazzelli mandarin-type fruit, Minneola tangelo and Salustiana and Shamouti orange) were minimally processed as segments or juices and cold-stored for up to 12 or 15 days, respectively. The flavanone glycosides, ascorbic acid (AA) content and antioxidant capacity were determined during storage. Minimal processing had almost no effect on the main chemical constituents, but ascorbic acid decreased significantly in Minneola and Salustiana segments, with values ranging from 1.63 to 5.10 mg per gram of dry matter, although only in the last samples taken. One of the three juices (Salustiana) also showed a decrease in AA content. The segments and juices showed different behaviour during storage with regard to the flavonoid content, which ranged from 0.77 mg to 8.32 mg/g dry matter in Palazzelli mandarin and Red blush grapefruit, respectively. A significant increase in total flavonoids (mainly hesperidin) was found in the segments, while the juices showed a diminution in flavonoid content. Antioxidant capacity increased significantly in Red blush grapefruit juices and Salustiana orange segments, decreased in Salustiana juices and Minneola tangelo segments and remained constant in the other samples. The antioxidant capacity, moreover, was clearly correlated (r = 0.968 and r = 0.889 in segments and juices, respectively) with the ascorbic acid content rather than with the presence of flavanone glycosides. (C) 2003 Elsevier Ltd. All rights reserved.