Preharvest 1-methylcyclopropene (1-MCP) treatment effects on quality of spot and strip picked ‘Gala’ apples at harvest and after storage as affected by postharvest 1-MCP and temperature conditioning treatments

Abstract

‘Gala’ apples are susceptible to development of stem-end flesh browning and subsequently flesh browning (FB) throughout the fruit during storage. Factors causing the browning are not well understood. In this study, fruit were obtained from an orchard block either untreated or treated with preharvest 1-methylcyclopropene (1-MCP; Harvista™) at two different harvest dates, one week apart. Preharvest 1-MCP was applied 7 d before the first harvest. Based on the commercially acceptable red coloration (66%), fruit were spot picked at the first harvest date, stripped picked at the second harvest date, or the remaining fruit from the first spot pick harvested on the second harvest date. Fruit were then untreated or treated with 1-MCP after overnight cooling to 0.5 °C (no conditioning treatment) or 10 °C for temperature conditioning (10 °C for 7 d), followed by storage in 2 kPa O₂/2 kPa CO₂ at 0.5 °C for 6 months. Fruit were generally less mature when harvested at H1 (spot pick) than at H2 (spot or strip pick), and with preharvest 1-MCP than without, and had the lowest FB incidence after storage. The picking method did not affect fruit maturity or FB incidence, but strip picked fruit softened more in storage than selective picked fruit. Overall, FB incidence was reduced by 5.9-, 1.2- and 1.6-fold by preharvest 1-MCP, postharvest 1-MCP and by conditioning, respectively. I_AD values (higher values reflect higher chlorophyll concentrations) at harvest were positively correlated with flesh firmness, and negatively correlated with FB incidence. Preharvest 1-MCP treatment and early harvest contributes to reduced risk of FB development during storage of ‘Gala’ apples.