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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOLOGICAL, BEHAVIORAL, AND PHYSICAL CONTROL AS ALTERNATIVES FOR STORED PRODUCT AND QUARANTINE PESTS OF FRESH/DRIED FRUITS AND NUTS Title: Effect of gamma irradiation treatment at phytosanitary dose levels on the quality of ‘Lane Late’ navel oranges

Authors
item Mcdonald, Heather -
item Arpaia, Mary Lu -
item Capraso, Fred -
item Obenland, David
item Were, Lilian -
item Rakovski, Cyril -
item Prakash, Anuradha -

Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 9, 2012
Publication Date: July 19, 2013
Citation: Mcdonald, H., Arpaia, M., Capraso, F., Obenland, D.M., Were, L., Rakovski, C., Prakash, A. 2013. Effect of gamma irradiation treatment at phytosanitary dose levels on the quality of ‘Lane Late’ navel oranges. Postharvest Biology and Technology. 86:91-99.

Interpretive Summary: Importing countries sometimes require that navel oranges be treated to control potential insect pests prior to the fruit being allowed to enter the country. Chemical fumigation and heat or cold treatments can be used for this purpose but are time-consuming and may damage the fruit. Gamma irradiation of ‘Late Lane’ navel oranges was tested as an alternative treatment, utilizing doses of 200, 400 and 600 Gy and then storing for 1 day at 5°C, 3 weeks at 5°C (to simulate sea shipment to Asia) or 4 weeks (3 weeks at 5°C and 1 week at 20°C to simulate distribution to retail following sea shipment). Both trained and consumer panelists found visual damage in the form of increased pitting and visual damage in oranges treated at doses of 400 Gy and above. Color, total phenolic content, vitamin C and the antioxidant capacity of the fruit were not affected by irradiation, while increased weight loss, decreased sugars and increases in certain aroma volatiles occurred at doses above 400 Gy. The results indicate that further research is needed to determine means to lessen negative irradiation effects on the appearance of the fruit if irradiation is to be accepted as a means to disinfest navel oranges of insect pests prior to export.

Technical Abstract: The objectives of this study were to determine the dose tolerance of ‘Lane Late’ navel oranges (Citrus sinensis L. Osbeck) to irradiation for phytosanitary purposes, identify the sensory attributes that may be affected by the treatment, and determine which changes, if any, influence consumer liking. ‘Lane Late’ navel oranges on Carrizo citrange (Citrus sinensis Poncirus trifoliate) rootstock were irradiated at target dose levels of 200, 400 and 600 Gy then stored for 1 day at 5°C, 3 weeks at 5°C (to simulate sea shipment to Asia) or 4 weeks (3 weeks at 5°C and 1 week at 20°C to simulate distribution to retail following sea shipment). Trained sensory panelists found increased pitting and visual damage in oranges treated at doses of 400 Gy and above. Consumer liking scores for appearance were significantly lower for oranges treated at 400 Gy, however, their overall liking scores for those same oranges were not significantly different than control. Color, total phenolic content, Vitamin C and Oxygen radical absorbance capacity values were not affected by irradiation. Dose effects were seen in terms of visual damage, increased weight loss and increased concentration of certain volatiles and as well as decreased Soluble solids concentration at doses above 400 Gy. The primary effect of irradiation on fruit quality was external damage and pitting at doses of 400 Gy and above. Further research should consider pack configuration and/or combination treatments to possibly mitigate negative irradiation effects on appearance of the fruit.

Last Modified: 12/27/2014
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