Effects of Gamma Irradiation, Modified Atmosphere Packaging, and Delay of Irradiation on Quality of Fresh-cut Iceberg Lettuce

This study was conducted to investigate the effect of modified atmosphere pack- aging (MAP) and delay of irradiation application on the quality of cut Iceberg lettuce. Overall visual quality and tissue browning of cut lettuce were evaluated using a scale of 9 to1,whereastexturewasanalyzedinstrumentallyduring14daysofstorageat4 8C.Results showed that irradiation (0.5 and 1.0 kGy) of cut lettuce induced tissue browning when stored in air; however, when cut lettuce was stored in MAP, irradiated lettuce had better appearance than the non-irradiated ones as a result of lower O2 levels in the packages of irradiated samples compared with the levels in control packages. In general, irradiation at dosesof0.5and1.0kGydidnotaffectfirmnessofthelettuce.After14daysofMAPstorage, overall visual quality of non-irradiated samples had a score of '4, a score below the limit of sales appeal, whereas the two irradiated samples had scores of 6.5 to 7.9, indicating the irradiated samples had a fair to good quality. Delaying irradiation by 1 day after prep- aration of cut lettuce did not significantly (P > 0.05) affect cut edge browning, surface browning, or overall visual quality compared with lettuce irradiated immediately after preparation. Our results suggest that MAP is essential to minimize quality deterioration caused by irradiation.

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