‘Honeycrisp’ Apple (Malus domestica Borkh.) Fruit Response to Controlled Atmosphere Storage with the Low Oxygen Limit Established by Monitoring Chlorophyll Fluorescence

Abstract

Postharvest management of apple fruit ripening using controlled atmosphere (CA) storage can be enhanced because CA oxygen concentration is decreased to close to the anaerobic compensation point (ACP). Monitoring fruit chlorophyll fluorescence (CF) is a technology to assess fruit response to low pO2 as fluorescence increases as pO2 reaches a critically low concentration. This type of pO2 management has been referred to as dynamic atmosphere storage (DCA). Use of very low pO2 can enhance post-storage apple fruit quality for many cultivars, allowing better firmness retention and prevention of superficial scald, compared with fruit stored at higher pO2 during CA. ‘Honeycrisp’ is a chilling-sensitive cultivar with little risk of firmness loss or superficial scald during storage; however, other aspects of fruit-quality loss during storage, including soluble solids content (SSC), titratable acidity (TA), peel greasiness, and physiological disorder development may be impacted by pO2. A 2-year study was conducted to identify ‘Honeycrisp’ fruit-quality impacts of CA storage with a low-pO2 setpoint determined by using CF. ‘Honeycrisp’ apples were held 7 days at 10 °C after harvest, then at 3 °C. An additional treatment with 1-methylcyclopropene (1-MCP) was conducted in year two. CA was established 48 hours after transfer to 3 °C. In both years, fruit CF increased when pO2 decreased to ≈0.3 kPa O2 and then decreased after pO2 was increased to 0.5 kPa. Additional CA pO2 concentrations above 0.3 kPa were also maintained for other fruit. Fruit internal disorder incidence increased as pO2 decreased and with 1-MCP use. Changes in SSC, TA, and peel yellowing were inconsistently reduced by storage at lower pO2. Peel greasiness did not develop in either year. CA did not impact the incidence of chilling disorders regardless of pO2. Results indicate some aspects of ‘Honeycrisp’ fruit quality can be enhanced as CA pO2 decreases; however, pO2 above the low pO2 threshold did not prevent internal physiological disorder development.