Influence of gamma irradiation on volatile flavour profiles and physicochemical attributes of navel oranges (Citrus sinensis L.) under post-irradiation storage

The effects of irradiation at 0.5 - 2.0 kGy on physicochemical and volatile characteristics of navel oranges stored at 4 degrees C were investigated. Fruit firmness was maintained when oranges were irradiated at 0.5 kGy, whereas samples irradiated at higher intensities exhibited lower firmness. The total soluble solids, titratable acidity, vitamin C content, total phenolic content and radical-scavenging activity were influenced by irradiation. However, at 0.5 and 1.0 kGy, these parameters were similar to those in non-irradiated control samples. These quality properties showed a significant decrease throughout the storage period. Principal component analysis (PCA) of the volatile pattern data obtained using electronic nose distinguished irradiated oranges from control fruits even after prolonged storage. The main volatile compounds, as determined using Kovats retention indices, were aldehydes and acetic esters at varying concentrations. Overall, irradiation doses of < 1.0 kGy had negligible effects on the quality properties of imported oranges. Appropriate dose range of gamma irradiation (0.5 - 1.0 kGy) proved very efficient, and the sensorial and nutritional qualities of navel oranges were maintained during extended storage of oranges at 4 degrees C. These findings may be helpful in meeting guidelines of exporting irradiated foodstuffs especially navel oranges to facilitate international trade. (C) All Rights Reserved