REDUCED PO₂ BETTER MAINTAINS VISUAL QUALITY, FRESH WEIGHT, AND ANTIOXIDANT CONTENT OF BUNCHED RADISH (RAPHANUS SATIVUS L.) THAN AIR STORAGE

The effect of reduced O₂ atmosphere on shelf life of radish (Raphanus sativus L.) was investigated. Bunched radishes were stored in 2 kPa O₂ or ambient air (21 kPa O₂) for 6 days at 10°C. Leaf discoloration developed in both treatments during storage, as indicated by higher L* and chroma values and lower hue, but the changes were reduced by low pO₂. In particular, low pO₂ reduced yellowing during storage as indicated by maintenance of lower a* value. Red coloration of hypocotyls increased during storage, but was not affected by storage atmosphere. Weight loss of bunched radishes was <1.5%, but was 2-fold higher in air compared with 2 kPa O₂. Ascorbate content and total antioxidant capacity decreased during storage, but remained higher in radishes stored in low pO₂. Phenolic content did not change during storage. Peroxidase and ascorbate peroxidase activities declined during storage, but were unaffected by the storage atmosphere, while catalase activity increased in both atmospheres, resulting in significant decreases in hydrogen peroxide content. The results of this study indicate that storage of bunched radishes in reduced pO₂ is beneficial for maintaining fresh weight and leaf color, as well as reducing losses of ascorbate and antioxidant capacity in the hypocotyls, without induction of plant oxidative stress.