Retention of Quality and Nutritional Value of Thirteen Fresh-cut Vegetables Treated with Low Dose Radiation

Authors: Fan, Xuetong; Sokorai, Kimberly

Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/3/2008
Publication Date: 7/1/2008
Citation: Fan, X., Sokorai, K.J. 2008. Retention of Quality and Nutritional Value of Thirteen Fresh-cut Vegetables Treated with Low Dose Radiation. Journal of Food Science. 73(7):S367:S372.

Interpretive Summary: Consumers are strongly encouraged to eat more fresh produce for health benefits. Unfortunately, in recent years, there has been an increase in the number of outbreaks and recalls associated with consumption of fresh produce due to contamination with human pathogens such as E. coli O157:H7. The industry is in need of a “kill” step to ensure produce safety and gain the confidence of consumers. Many studies have demonstrated that a dose of 1 kGy radiation can achieve at least 99.999% reduction of E. coli O157:H7 surface inoculated on fresh produce. However, it is unclear whether fresh-cut produce can tolerate this dose level of radiation without changes in quality attributes. This study was conducted to investigate the effects of 1 kGy irradiation on the quality of thirteen common fresh-cut vegetables: Iceberg, Romaine, red and green leaf lettuce, spinach, tomato, cilantro, parsley, green onion, carrot, broccoli, red cabbage, and celery. Our results showed that the appearance, texture, and aroma of most fresh-cut vegetables were not negatively affected by the 1 kGy radiation. The appearance and aroma of many irradiated vegetables were better than that of the untreated samples after 14 days storage, likely due to the reduction of decay and browning. However, vitamin C content was reduced by irradiation in a few vegetables. Overall, our results demonstrated that most fresh-cut vegetables can tolerate 1 kGy radiation without deterioration in quality. The information should help fresh produce industry to adopt ionizing irradiation in improving the safety of fresh vegetables.

Technical Abstract: The recent outbreaks associated with consumption of spinach, lettuce and tomato have resulted in much concern over the safety of fresh-cut vegetables. The industry is in need of a “kill” step to ensure the safety of fresh-cut vegetables. Many studies have demonstrated that a dose of 1 kGy radiation can achieve at least a 5-log reduction of E. coli O157:H7 surface inoculated on fresh produce. However, it is unclear whether all fresh-cut produce can tolerate this dose level of radiation. This study was conducted to investigate the effects of 1 kGy radiation on the quality of thirteen common fresh-cut vegetables: Iceberg, Romaine, green and red leaf lettuce, spinach, tomato, cilantro, parsley, green onion, carrot, broccoli, red cabbage, and celery. Results showed that the appearance of irradiated samples were similar as the non-irradiated ones except that irradiated carrots, celery, cilantro and green onions had higher appearance scores than corresponding non-irradiated vegetables. There was no difference in the instrumental texture between irradiated samples and non-irradiated ones. The aroma of several irradiated vegetables was significantly better than controls after 14 days storage, as these control samples decayed or senesced. The 1 kGy radiation did not affect vitamin C content of most vegetables; however, irradiated green and red leaf lettuce had 24-53% lower vitamin C contents than the controls. Our results suggest that most fresh-cut fruits and vegetables tested can tolerate up to 1 kGy radiation without significant losses in any of the quality attributes.