Interaction of nitric oxide and extremely low oxygen storage on volatile organic compounds and overall quality of ‘Maxi Gala’ apples

Abstract

This study aimed to evaluate the effect of nitric oxide (NO) application on overall quality and volatile compounds of ‘Maxi Gala’ apples stored under controlled atmosphere (CA) and with extremely low oxygen (ELO). The fruit were treated or not with NO at the beginning and end (10 + 10 µL L⁻¹), or only at the end of storage (10 µL L⁻¹) and, were stored under the following conditions: [1] CA (1.2 kPa O₂; 1.6 kPa CO₂) + 1-methylcyclopropene (CA + 1-MCP); [2] ELO (0.4 kPa O₂; 1.6 kPa CO₂); [3] ELO + 0.4 hysteresis; [4] ELO + 0.6 hysteresis and; [5] dynamic controlled atmosphere by respiratory quotient (DCA-RQ 1.3; 1.6 kPa CO₂). After 7.5 months storage, plus 7 d shelf life, the fruit quality was evaluated. Fruit stored under ELO exhibited higher ACC oxidase activity, ethylene production, and respiration rate. ELO + 0.6 hysteresis maintained higher flesh firmness without NO application and suppressed total esters content similarly to CA + 1-MCP, but with less impact on 2-methylbutyl acetate. NO application at the beginning and end of storage resulted in higher concentrations of aldehydes, alcohols, and esters, but it reduced the concentration of phenolic compounds and flesh firmness, and increased the incidence of mealiness in CA + 1-MCP and DCA-RQ. NO applied only at the end of storage did not improve fruit quality. Thus, the reapplication of NO should be better evaluated under extremely low oxygen storage, although it can be a promising strategy to enhance the aromatic quality of fruit.