Abstract:

The fresh-keeping effect of sodium hypochlorite or chlorine dioxide treatment on fruits and vegetables has been reported previously. The application of calcium hypochlorite, however, is confined to disinfection of plant seeds and egg products and control of bacteria in plant tissue culture. Up to now, no studies focusing on fresh-keeping effect of calcium hypochlorite have been reported. This study particularly focused on the effects of calcium hypochlorite, sodium hypochlorite and imazalil at two concentrations (300 mg/L and 500 mg/L) on relative conductivity (RC) of fruit peel of “Newhall” navel oranges and malondialdehude (MDA) content and activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) in fruit pulp. The increases of RC and MDA content were inhibited and the activities of SOD, CAT and POD were enhanced by calcium hypochlorite treatment at 300 mg/L. However, significant inhibition effects of calcium hypochlorite treatment at 500 mg/L were observed on the increases in RC, MDA content and CAT activity and the decrease in SOD activity, whereas this treatment concentration was favorable to the increase in POD activity. In summary, calcium hypochlorite treatment shows better effects at 300 mg/L than at 500 mg/L.

Key words: “Newhall&rdquo, navel orange, calcium hypochlorite, defensive enzymes, membrane lipid peroxidation