Effect of short-term exposure to CO2-enriched atmospheres on 'Valencia' orange quality

Abstract

Quarantine treatments must be currently applied to Spanish citrus export shipments to markets such as the US because of the endemic presence in the Mediterranean area of the Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae). The current accepted quarantine treatment is fruit exposure to temperatures ranging from 1.1 to 2.2°C. Alternative or complementary treatments are needed because fruit quality of some cold sensitive cultivars can be adversely affected by this treatment. Since CO2 has shown insecticidal activity, short-term exposure to this gas may be an interesting complement. In the present work, ‘Valencia’ orange (Citrus sinensis) quality was assessed on fruit exposed to 98% CO2 at 22°C for 8, 16, and 24 h, stored at 5°C for 7, 14, and 21 days, and then kept at 20°C for 7 days to simulate shelf life. The following quality and sensory attributes were analyzed on treated and control fruit: rind color and firmness, maturity index, juice yield, the fermentative volatile compounds ethanol and acetaldehyde, taste, and chewiness. No general negative effects were observed in CO2-exposed fruit. Ethanol content was significantly higher on fruit exposed to the gas for 24 h and stored at 5°C for 21 days than on control fruit. However, ethanol content on treated fruit did not reach 200 mg per 100 ml of juice. As a conclusion, exposure to CO2-enriched atmospheres shows promise as a complementary treatment for the control of C. capitata on citrus cold-sensitive cultivars