Management of ethylene production, superficial scald and fruit quality in ‘Granny Smith’ apple using organic oils and ozonised cold storage

Abstract

Ethylene management during storage of organically grown apples is challenging due to limited number of treatment and storage options that are available for organic produce. In this study the effects of fumigation with lemon and cinnamon oils on ethylene production, superficial scald incidence, and fruit quality in 'Granny Smith apples' placed in cold storage with and without application of ozone were evaluated. The fruit were fumigated with 3 µL L‑1 lemon or cinnamon oil for 24 h while untreated fruit were used as a control. Following the treatments, the fruit were put into cold storage at 0±2, with and without ozone for 100 or 150 days. After each storage period, ethylene production, superficial scald incidence, and fruit quality parameters were recorded. The fruit fumigated with lemon oil was significantly reduced climacteric ethylene peak rates after 100 and 150 days cold storage. The mean rate at which the ethylene climacteric peak developed was significantly reduced in fruit stored in ozonised cold storage compared to the peak level in fruit stored without ozone for 100 days. The climacteric ethylene peak was significantly delayed in the fruit cold stored with ozone (8.78 d) as compared to without ozone (3.89 d) following 100 days storage. Fruit firmness was significantly higher in fruit fumigated with lemon or cinnamon oil compared to control fruit for both storage times. Lemon or cinnamon oil fumigation significantly reduced superficial scald in the cold-stored fruit with or without ozone. The fruit fumigated with lemon oil or cinnamon oil following 150 days cold storage resulted in significantly higher levels of ascorbic acid and antioxidant capacity compared to control fruit. Overall, lemon oil fumigation was more effective in suppressing ethylene production in 100 and 150 day cold-stored fruit than cinnamon oil. Notably, fumigation with lemon or cinnamon oil were effective in reducing superficial scald and maintaining quality in 100 and 150 days cold-stored fruit.