Submitted to: Journal of the Science of Food and Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 11, 2004
Publication Date: January 26, 2005
Citation: Fan, X. 2005. Antioxidant capacity of fresh-cut vegetables exposed to ionizing radiation. Journal of the Science of Food and Agriculture. 85: 995-1000. Interpretive Summary: Ionizing radiation inactivates foodborne pathogens, improves hygiene quality and extends shelf-life of many fresh fruits and vegetables. Fresh fruits and vegetables are rich in antioxidants which exhibit properties that prevent cancer and reduce mortality due to cancer and heart diseases. The impact of ionizing radiation on the antioxidant capacity of fresh fruits and vegetables is unclear. Therefore, this study was conducted to investigate irradiation-induced changes in antioxidant capacity of three common salad green vegetables. Results indicated that irradiation enhanced antioxidant capacity of the salad green vegetable in a dose dependent fashion. However, increased tissue browning was also observed in Iceberg lettuce. Currently, a maximum dose of 1 kGy has been approved by U.S. authority for use of ionizing radiation on fresh fruits and vegetables. At 1 kGy, antioxidant capacity was increased by at least 14% in lettuce and endive after 8 days of post-irradiation storage. Our results suggest that irradiation increased nutritional quality of vegetables in addition to the well- known benefit of improving microbial food safety. The information should encourage the produce industry to use ionizing radiation, and consumers to accept this technology.
Technical Abstract: The effect of ionizing radiation on antioxidant capacity, phenolic content and tissue browning of three vegetables was studied. Midrib and non-midrib leaf tissues of Romaine and Iceberg lettuce and endive were irradiated with gamma rays at 0, 0.5, 1, and 2 kGy, and then stored at 7-8 C for 8 days. Antioxidant capacity and phenolic content of tissues as well as tissue browning were analyzed at 1, 4 and 8 days of storage. In general, irradiation increased phenolic content and antioxidant capacity of both tissue types of all vegetables at day 4 and day 8. The rates of the increase were higher in midrib tissues than in non-midribs, and increased with storage time. Irradiation, however, increased tissue browning of midrib tissues of Romaine and Iceberg lettuce. Our results suggest that irradiation increased nutritional quality of leafy vegetables, but some adverse visual quality changes were encountered.