Dynamics of metabolic adaptation during initiation of controlled atmosphere storage of 'Jonagold' apple: Effects of storage gas concentrations and conditioning

- The dynamics of metabolic changes during CA initiation was investigated.
- Clear metabolic differences were obtained between air and CA stored apples.
- CA induced changes in the glycolysis, TCA cycle and amino acid metabolic pathways.
- The metabolic response of immediate and delayed CA stored apples were similar.

Controlled atmosphere (CA) storage reduces respiration, ethylene production and related biochemical and physiological changes. The dynamics of the metabolic changes accompanying initial periods of CA storage of 'Jonagold' apples have been studied. The apples were exposed to 1 kPa O2, 3 kPa CO2; 3 kPa O2, 3 kPa CO2; 1 kPa O2, 10 kPa CO2 and air (20.8 kPa O2, 0.03 kPa CO2) was used as a control. The effect of air storage preceding CA storage was also investigated. In response to CA, metabolic changes were observed in glycolysis, tricarboxylic acid cycle, amino acids and other metabolites linked with these pathways. In general, stress response patterns of immediate and delayed CA stored apples were similar. Aspartate and 1-aminocyclopropane-1-carboxylic acid were positively correlated with O2 concentration during the first two days and after one week of storage, respectively, while glucose-6-phosphate and some amino acids such as proline, alanine and threonine were negatively correlated with O2 concentration. Glutamate and succinate were correlated with CO2 concentration. Galactinol substantially increased with storage time. The observed metabolic changes are discussed in the context of adaptation mechanisms of the fruit to CA storage.