Browning of ‘Empire’ and ‘Fuji’ Apples as Affected by Antioxidant Activities

Abstract

Internal ethylene concentration (IEC) and activities of peroxidase (POX), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) were analyzed to evaluate their effects on browning in late-harvested ‘Empire’ apples (Malus × domestica Borkh.), during air storage at 0.5 °C for five months, and for ‘Fuji’ apples treated with 1-methylcyclopropene (1-MCP), stored for seven months. IEC remained higher in the ‘Empire’ apples compared to values observed in the ‘Fuji’ apples for up to three months in storage, although 1-MCP treatment reduced the IEC in both fruit cultivars. Antioxidant enzymes, such as PPO, POX, and PAL, mostly increased in the flesh and core tissues in both 1-MCP-treated apple cultivars, but were slightly higher in the ‘Empire’ apples between one and three months of storage time. Browning developed in the ‘Empire’ apples after three months of storage, with high susceptibility to incidences of browning observed on the 1-MCP-treated fruit.

Keywords

• apples
• browning disorder
• peroxidase
• phenylalanine ammonia-lyase
• polyphenol oxidase