Responses of 'Rocha' pear to delayed controlled atmosphere storage depend on oxygen partial pressure

- Delayed controlled atmosphere storage affected the incidence of internal disorders.
- Effect of delayed oxygen pull down depend on O2 partial pressure during storage.
- Delay O2 pull down reduced incidence of internal disorders in fruit stored at 3.0 kPa.
- Delay O2 pull down strongly increased internal disorders at 0.5 kPa.
- Under extremely low pO2, delayed CA storage was detrimental for the quality of 'Rocha' pear.

Internal disorders hinder long-term controlled atmosphere (CA) storage of 'Rocha' pear. The delayed establishment of CA regime is often recommended to reduce internal disorders in pear. This investigation evaluated the effect of delayed CA at two oxygen partial pressures (pO2) at constant low CO2 partial pressure (pCO2) on internal disorders and on storage potential of 'Rocha' pear. Fruit were stored at −0.5 °C for 257 d under 0.6 kPa CO2 combined with 0.5 or 3.0 kPa O2. The pull down of pO2 was imposed at the beginning of cold storage (immediate CA) or after 46 d (delayed CA). 'Rocha' pear tolerated immediate storage at 0.5 kPa O2 without developing internal disorders for 257 d storage. However, 63.3% of fruit immediately stored at 3.0 kPa O2 developed internal disorders. Delayed pull down of pO2 for 46 d reduced internal disorders in fruit at 3.0 kPa O2 to 35.5%, but increased the disorder incidence in fruit at 0.5 kPa O2 to 27.3%. Poststorage ethylene production rate was lower in fruit stored under delayed CA at 3.0 and 0.5 kPa O2. In conclusion, the immediate storage of 'Rocha' pear at 0.5 kPa O2 prevented the development of internal disorders for 257 d, while allowing adequate poststorage ripening and maintenance of quality traits. The effect of delayed CA on internal disorders depended on pO2. Delaying CA for 46 d did not benefit 'Rocha' pear during long-term storage.