Characteristics of a ‘Gala' Apple Fruit Internal Browning Storage Disorder

Factors contributing to development of an internal browning storage disorder developing primarily at the stem-end in ‘Gala’ apple fruit were investigated.  Initial storage temperature, storage duration, controlled atmosphere (CA) CO₂ concentration, delayed CA establishment, use of diphenylamine (DPA) and/or 1-methylcyclopropene (SmartFresh®), and fruit weight were evaluated.  Browning can occur during storage or during a subsequent 7 day shelf-life period.   Large fruit are at increased risk of browning development.  Browning develops in fruit stored at 0.5 ^oC in air or CA (1.5 kPa O₂, 1-5 kPa CO₂).  Storage at 0.5 ^oC for 7 days in 17 kPa O₂/3 kPa CO₂ then air or CA does not enhance browning development.  In 2 of 3 crop years, SmartFresh®-treated fruit developed browning sooner compared to controls.  DPA does not control browning development regardless of storage environment or use of SmartFresh®.  Cooling fruit to 0.5 ^oC after 7 days at 10 ^oC reduces or eliminates browning development regardless of SmartFresh® use.  Delayed SmartFresh® treatment does not impact browning development but results in poor quality if fruit are held 7 days at 10 ^oC prior to 0.5 ^oC.  The results indicate this disorder may result from chilling injury, and that chemical inhibition of ethylene action can enhance fruit susceptibility.  Prompt treatment with SmartFresh® and cooling fruit to 10 ^oC for the initial 7 days after harvest can reduce or prevent disorder development while maintaining fruit quality comparably to fruit treated with SmartFresh® and cooled to 0.5 ^oC after harvest.