Differences in ethylene and fruit quality attributes during storage in new apple cultivars

Physiological characteristics of five new apple cultivars from the Korean apple breeding program were evaluated as a function of harvest time and storage after harvest. Internal ethylene concentration (IEC), flesh firmness, soluble solids concentration (SSC), and titratable acidity (TA) were measured in ‘Summer Dream’, ‘Summer King’, ‘Green Ball’, ‘Picnic’, and ‘Hwangok’ apples at harvest, during shelf life at 20°C, and one day after cold storage at 0.5°C in air. IEC increased during shelf life in ‘Summer Dream’, ‘Summer King’, and ‘Green Ball’ but not in ‘Picnic’ or ‘Hwangok’, regardless of harvest time. Flesh firmness decreased towards harvest time and decreased gradually with time in cold storage only in the former three cultivars. In turn, IEC increased during cold storage in the first three cultivars but not for the last two cultivars, irrespective of harvest time. Changes in SSC and TA did not consistently relate to harvest time or storage period but TA tended to decrease as IEC increased. Furthermore, IEC was negatively correlated with flesh firmness except in the ‘Green Ball’ cultivar but the significance level was much greater in ‘Summer Dream’ and ‘Summer King’ (p < 0.0001) than in ‘Picnic’ (p < 0.01) or ‘Hwangok’ (p < 0.05) cultivars. Flesh firmness was positively correlated with TA in the first three cultivars but not in the last two cultivars. Overall, the results indicate that cultivars for which IEC increased after harvest had reduced flesh firmness and TA after storage.