IAD Values in Relation to Physiological Storage Disorders of 'Honeycrisp' Apples

The 'Honeycrisp' apple is highly prone to developing physiological disorders such as soft scald, bitter pit, and core browning during storage, but disorder incidences are affected by fruit maturity stage. To investigate relationships between fruit maturity and physiological disorders, a difference of absorbance meter was used to separate fruit into index of absorbance difference (IAD) value categories with the objective of reducing fruit-to-fruit variability within a population of fruit harvested at any one time. Fruit from two harvest dates, 10 days apart, were separated by IAD values and stored at 0.5 or 3 degrees C. The internal ethylene concentration (IEC) of fruit during storage and the incidence of physiological disorders after 18 weeks were assessed. The results indicate that earlier harvest, colder storage temperature, and lower IAD values (less green fruit) were associated with lower IECs during storage. The incidences of soft scald, bitter pit, and core browning, as well as superficial scald, were affected by IAD values within each harvest date and storage temperature, and more precisely than an evaluation of bulked fruit samples. This study highlights the potential of categorizing fruit by IAD values as a tool to minimize variation of fruit within a population and therefore increase sensitivity of investigations into factors affecting storage performance.