Cold quarantine responses of blood oranges to postharvest hot water and hot air treatments

The potential of hot water dipping (HWD) for 3 min at 50 C and hot air treatment (HAT) at 37 C for 48 hours to control chilling injury and decay in ‘Tarocco’, ‘Moro’, ‘Sanguinello’ and ‘Doppio sanguigno’ blood oranges during cold quarantine at 1 C for 16 days, subsequent storage at 8 C for 3 weeks and an additional week of simulated marketing period (SMP) at 20 C was investigated over two years’ harvest seasons. Unheated and non-HWD fruit were used as controls. Chilling injury (CI) occurred mostly during storage at 8 C and subsequent SMP, rather than during quarantine at 1 C, and predisposed fruit to decay, especially during SMP. The cultivars ‘Tarocco’ and ‘Moro’ were more susceptible to CI than ‘Doppio sanguigno’ and ‘Sanguinello’. HWD and HAT similarly reduced the incidence of CI in all cultivars, and neither treatment caused visible damage to the fruit. HWD did not affect fruit firmness, taste and flavour (organoleptic) traits and internal fruit quality attributes (juice yield, soluble solids concentration, titratable acidity, ascorbic acid and juice ethanol concentrations). By contrast, HAT caused a significant decrease in fruit firmness, adversely affected fruit organoleptic acceptance and internal quality characteristics. Thus, while HWD can have important commercial applications in minimising the risk of CI and decay of quarantined fruit, HAT cannot be recommended to improve keeping quality of blood oranges following cold disinfestation for fruit fly.