Influence of 1-methylcyclopropene (1-MCP), diphenylamine (DPA), and CO2 concentration during storage on 'Empire' apple quality

The objectives of this study were: (1) to determine the effects and interactions of 1-methylcyclopropene (1-MCP) and diphenylamine (DPA) on the quality of 'Empire' apples during storage and (2) to investigate the effects Of CO2 in the CA regime for 'Empire' apples treated with 1-MCP. 'Empire' apples were harvested, treated with or without DPA (1 g L-1) and 1-MCP (1 mu L L-1, 24 h at 0 degrees C), and subsequently stored in controlled atmosphere (CA) of 2.5 kPa O-2 with either 2 or 0 kPa CO2 for 120 and 240 days at 2 degrees C. DPA treatment had no significant effect on CO2 production, ethylene, and total volatiles, while apples not treated with 1-MCP were firmer with DPA than without DPA. 1-MCP-treated fruit were firmer than those not treated with 1-MCP, while untreated fruit held in CA with CO2 were firmer than those held with no CO2. 1-MCP-treated fruit held in CA with CO2 were slightly firmer than those held in CA without CO2 after 240 days of storage. 1-MCP effectively suppressed CO2 production, ethylene and total volatiles in fruit in CA storage and after removal to air, but recovery of these metabolic processes occurred sooner with longer CA storage duration. CO2 in the storage regime further suppressed CO2 production, ethylene, and total volatiles in 1-MCP-treated apples. These results confirm the importance of DPA treatment and CO2 in the CA regime for maintaining 'Empire' apple quality, especially after long-term storage. However, 1-MCP treatment mimics the beneficial effect Of CO2 on firmness. The data suggests that CO2 Could be eliminated or reduced in CA regimes for 'Empire' apples treated with 1-MCP, in order to reduce susceptibility to CO2 injury and shorten recovery time of metabolic processes upon removal from CA. (c) 2005 Elsevier B.V. All rights reserved.