Tolerance of `Valencia' Oranges to Controlled Atmospheres, as Determined by Physiological Responses and Quality Attributes

Abstract

`Valencia' oranges [Citrus sinensis (L.) Osbeck] tolerated up to 20 days of exposure to 0.5%, 0.25%, or 0.02% O 2 , at 5 or 10C followed by holding in air at 5C for 7 days without any detrimental effects on external and internal appearance. Oranges stored in 0.5%, 0.25%, or 0.02% O2 had lower respiration rates, but higher resistance to CO, diffusion and higher ethanol evolution rates than those stored in air at 10C. Similar, but less pronounced, effects of the low O 2 atmospheres were observed at O and SC. Respiration rates, internal CO 2 concentrations, and ethanol evolution rates were generally higher at 10C than at 0C, while resistance to CO 2 diffusion was lower at the higher temperature. `Valencia' oranges kept in 60% CO 2 at 5C for 5 to 14 days followed by holding in air at 5C for 7 days developed slight to severe injury that was characterized by skin browning and lowered external appearance scores. Juice color, soluble solids content, pH, titratable acidity, and ascorbic acid content were not significantly influenced by either the low O 2 or the high CO 2 treatments. However, these treatments increased ethanol and acetaldehyde contents, which correlated with the decrease in flavor score of the fruits. Ethanol content of the oranges transferred to air following low 0 2 treatment correlated with CO 2 production rate of the fruits at the transfer temperature and was related to ethanol evolution and probably production rates after the transfer.