High CO2 level affects ascorbate metabolism in controlled-atmosphere stored pears

The effects of cold and CA storage on ascorbate metabolism were studied. Total ascorbate significantly decreased during storage following a biphasic curve. During the first phase, ascorbate rapidly decreased whatever the storage condition. During the second phase, ascorbate was regenerated when the fruits were kept in cold storage or partially regenerated at 0.7% CO2. In the fruits stored at 5% CO2, ascorbate levels remained very low. From the analysis of the redox forms of ascorbate and of the enzymes involved in its oxido-reduction, it was concluded that the effect of CO2 was not due to a change in the redox state of ascorbate but rather to a change in its biosynthetic pathway.