Abstract:

The aim of this study was to investigate the effects of chitosan, SiOx and their combination on the firmness of
“Fengji” navel orange fruit during storage. The mechanism involved was explored by measuring the contents of compounds
and the enzyme activities related to the cell wall structure in peels. The results indicated that 1.5% chitosan and/or
0.08% SiOx could significantly delay the decrease of orange fruit firmness during storage. Meanwhile, the best effect was
achieved by the combined treatment. All three treatments could delay the degradation of pectin, suppress the increase
of soluble pectin, increase the contents of cellulose and lignin, and inhibit the activities of pectin methylesterase (PME),
polygalacturonase (PG) and cellulase. In conclusion, both the individual and combined treatments can reinforce the strength
of peel cell wall, inhibit the decrease of fruit firmness and maintain fruit quality by regulating the synthesis and degradation
of cell wall structural materials and inhibiting related enzyme activities.

Key words: chitosan, SiOx, navel orange fruit, firmness