Dynamic changes in conjugated trienols during storage may be employed to predict superficial scald in 'Granny Smith' apples

- ULO storage limits scald development depending on the fruit maturity at harvest.
- Changes in pro- or anti-oxidants during storage are not related to scald incidence.
- The accumulation dynamics of CTols during short-term storage may be employed to predict scald incidence.
- A novel and accurate predictive model for scald development has been developed.

In order to predict scald disorders in 'Granny Smith' apples, fruit were harvested from three different orchards and stored in controlled storage regimes of 2.5 kPa O2/2.5 kPa CO2 (CA) and 0.7 kPa O2/0.5 kPa CO2 (Ultra low oxygen; ULO) or in air after treatment with 1-MCP. Relationships between different oxidative markers (hydrogen peroxide, antioxidant potential, malondialdehyde), compounds related to α-farnesene metabolism (α-farnesene, conjugated trienols (CTols) including CTol258 and CTol281) and scald incidence were established. Our results showed that neither changes in fruit antioxidant potential, malondialdehyde nor the generation of hydrogen peroxide during storage were associated to scald and hence were not able to predict scald incidence. The ratio between conjugated trienols (CTol258/CTol281) failed to predict scald susceptibility on a short- or mid-term basis. In contrast, a novel and accurate model based on CTols accumulation dynamics (dCTols/dt) during early stages of storage (<50 days) is proposed. After validation of the model, a threshold value of δCTols/δt ≥ 5.5 is defined to predict scald occurrence in 'Granny Smith' apples.