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  • Author or Editor: Yosef Al Shoffe x
  • HortScience x
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Cold storage is a commonly adopted technology to maintain quality and extend shelf life; however, depending on the cultivar, ethylene production can be enhanced by short-term cold treatments. In this study, index of absorbance difference (IAD) values, which reflect skin chlorophyll concentrations of cold-influenced ripening patterns, of ‘Gala’ apples were investigated. Fruit that were untreated or treated with aminoethoxyvinylglycine (AVG), which is a plant growth regulator that inhibits ethylene production of fruit, were harvested from a commercial orchard. Two IAD value categories 0.6 to 0.8 and 0.2 to 0.4 were chosen from a single harvest in 2019, whereas in 2020, the fruit in categories 0.6 to 0.8 and 0.2 to 0.4 were chosen for two harvests separated by 1 week, respectively. In 2019, only ethylene production was measured. In 2020, ethylene production, respiration, internal ethylene concentration (IEC), flesh firmness, 1-aminocyclopropane-1-carboxylate (ACC), and malonyl 1-aminocyclopropane-1-carboxylate (MACC) concentrations of fruit kept in air at 20 °C or stored at 0.5 °C for 21 days and then transferred to 20 °C were measured. The results were different from those described in the literature for cold-enhanced ethylene production of ‘Gala’ apples. Although ethylene production occurred without cold exposure of untreated fruit, exposure of fruit to 0.5 °C for 21 days resulted in more rapid and higher ethylene production rates and IEC than for fruit kept at only 20 °C. Ethylene production was suppressed by the preharvest AVG treatment, especially in 2020. The rates of respiration and softening of non-AVG treated fruit were enhanced by cold treatment. The effects of cold treatment were more significant for less mature fruit as indicated by higher IAD values.

Open Access

‘Honeycrisp’ apples are susceptible to the physiological disorder soft scald, especially when stored at temperatures close to 0 °C. The disorder can be reduced by a conditioning treatment of 10 °C for 7 days before storage, but little is known about the underlying physiology of disorder development. The effects of storing ‘Honeycrisp’ apples in air at 0.5 °C for a total of 140 days, without and with conditioning, on internal ethylene concentration (IEC), ethanol and acetaldehyde concentrations, and activities of alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC) were investigated in relation to soft scald incidence. Fruit were selected on the basis of background color (chlorophyll concentration) using a nondestructive delta absorbance (DA) meter to minimize variability of fruit maturation. Conditioning reduced soft scald incidence to 1% compared with 28% in unconditioned fruit. During the conditioning period, IECs were usually greatest in the conditioned fruit, with no effect on ethanol and acetaldehyde concentrations. During subsequent storage, IEC was greatest in conditioned fruit, whereas ethanol and acetaldehyde concentrations were generally less. However, ADH and PDC activities were unaffected consistently by conditioning or during storage.

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