Mass loss by low relative humidity increases gas diffusion rates in apple flesh and allows the use of high CO2 partial pressures during ultralow O2 storage

Gas diffusion rate in fruit flesh (O2 uptake and CO2 release) is crucial to reduce physiological disorders and maintain the quality of apples during controlled atmosphere (CA) storage. The main goal of this paper was to evaluate the effect of mass loss on gas diffusion rate and sensitivity to high CO2 partial pressure on 'Royal Gala' and 'Galaxy' apples (Malus domestica Borkh.) during CA storage. Thereby, two experiments (E1-'Royal Gala' and E2-'Galaxy') were carried out: in E1, two levels and periods of mass loss induced by low relative humidity (RH) were evaluated: 3 or 1% of mass loss during initial of storage period (initial) or throughout all storage period (linear). In E1, fruits were stored in CA with 1.2 kPa O2 + 2.0 kPa CO2. In E2, low O2 (0.4 kPa) and high CO2 (3 kPa) partial pressure associated with mass loss of 3% (initial or linear) were assessed. One of the main parameters evaluated was gas diffusion rate. After storage, we founded that mass loss induced by low RH, increased gas diffusion in flesh of 'Royal Gala' and 'Galaxy' apples, reduced pulp cracking, flesh breakdown and mealiness during CA storage. 3% linear or initial mass loss, maintained better 'Royal Gala' apple quality compared to 1% of mass loss. 3% initial mass loss, by low RH (90%) during two months, may allow a high CO2 partial pressure (3.0 kPa) use during the storage of 'Galaxy' apple in CA.