Mechanism of ozone treatment in delayed softening of fresh-cut kiwifruit during storage

Firmness is one of the most important factors affecting the quality and commercial value of fresh-cut kiwifruits. The aim of this study was to investigate the effects of 1 mg/L of gaseous ozone treatment for 10 min on the texture of fresh-cut kiwifruit stored at 4 °C for 12 d. Ozone treatment relatively maintained the firmness of the fresh-cut fruit for 12 d compared with the untreated group. Laser scanning confocal microscopy (LSCM) showed that endogenous free Ca2+ was higher and more evenly distributed in ozone-treated fruits than in the untreated group, and correlation analysis indicated that the higher the Ca2+ concentration, the greater the formation of Ca-pectinate. Additionally, ozone treatment inhibited the activity of cell wall polysaccharide-degrading enzymes, suppressed electrolyte leakage and malondialdehyde and hydrogen peroxide contents, and maintained protopectin and cellulose levels, thereby preventing fruit softening. Overall, these results showed that ozone treatment delayed the softening of fresh-cut kiwifruit by increasing endogenous Ca2+ concentrations and preventing polysaccharide solubilization.