Abstract:

This study aimed to investigate the effect of inflatable packaging at different CO2 concentrations on the
postharvest quality and shelf-life quality of Red Fuji apple fruit and to explore the concentration threshold for CO2 injury
in apples. The apples were packaged in atmospheres containing CO2 at different concentrations (2%, 5%, and 8%) or in the
normal atmosphere (which contains 0.03% CO2, approximately considered as zero) as control and then stored in PVC bags at
low temperature (0 ± 0.5) ℃. The postharvest quality, shelf-life quality at normal temperature at ten days after cold storage
and CO2 injury incidence of apples as well as gas concentrations changes in PVC bags were studied. The results showed
that during low temperature storage, the equilibrium concentration of CO2 in bags significantly differed among different
treatments. The 8% CO2 group reached an equilibrium concentration of 6.7%, significantly higher than that of the 2% CO2
group and the control. The time of occurrence of CO2 injury and the incidence of injury varied with the initial concentration
of CO2. The CO2 injury occurred later in the control and 2% CO2 groups than in other groups, and the incidence of injury was
also lower. Compared with other treatments, 2% CO2 could reduce the respiration rate, maintain higher fruit firmness, SSC
and TA, preserve the shelf-life quality, and inhibit the mass loss. Thus, 2% CO2 is the best concentration for inflatable packaging of
apples, whereas 5% and 8% CO2 can aggravate CO2 injury, consequently having a negative effect on apple quality.

Key words: Red Fuji apple, CO2 concentration inflatable packaging, CO2 injury, postharvest quality