Deastringency treatment with CO2 induces oxidative stress in persimmon fruit

• CO2 deastringency treatment was applied to persimmon fruit at three maturity stages.
• The CO2 treatment led to an oxidative stress state in the fruit.
• O2− and H2O2 levels were enhanced after CO2 treatment.
• SOD, CAT and APX enzyme activities were up-regulated after the deastringency treatment.
• Ripening in persimmon may also be linked to redox changes in the fruit.

Because of astringency at harvest, ‘Rojo Brillante’ persimmons are regularly submitted to deastringency treatment based on exposing fruit to a high CO2 concentration. The treatment conditions that ensure total astringency removal throughout the various maturity stages have been determined to be 95% CO2, 20 °C, 24 h. The aim of this study was to investigate changes in the redox state of persimmon fruit associated with this deastringency treatment. The levels of reactive oxygen species (ROS) (O2− and H2O2), and the activities of the main ROS scavenging enzymes (CAT, POD, APX, and SOD), were determined at harvest and after deastringency in fruit at three different maturity stages.Our results showed that during ‘Rojo Brillante’ persimmon maturation, the level of O2− gradually increased, while APX activity was lowered. The deastringency treatment with CO2 induced oxidative stress in the fruit, observed as an over-accumulation of O2− and H2O2. As a response to ROS accumulation, the activities of the CAT, APX and SOD scavenging enzymes were up-regulated after deastringency treatment. The response of POD enzyme was dependent on maturity stage, showing enhanced activity after CO2 treatment only for the fruit at the most mature stage.