Effect of irradiation on quality and bacterial populations in fresh-cut lettuce

⁶⁰Co-γ irradiation was used in fresh-cut lettuce's process, and effects of irradiation on lettuce's decontamination and nutrition were investigated to extend the shelf-life of fresh-cut lettuce. Results showed that γ-irradiation could effectively reduce bacteria load. Irradiation at the dose higher than 0.68 kGy could decrease total bacterial count (TBC), coliforms, mould and yeast to a relatively low level. Irradiation at the dose less than 2.32 kGy had no significant effect (5% level) on fresh-cut lettuce's weight loss, soluble solids and nitrite content, besides irradiation could delay the rate of Vc content's descent, but couldn't cause significantly effects on sensory index such as color, smell, tissue texture and flavor. In conclusion, irradiation at the dose range of 0.68 to 2.32 kGy could effectively control the microbe of fresh-cut lettuce without affecting its consumption and sensory quality, and could extend its shelf-life to six days. This article explored the feasibility of irradiation preservation used in the process of fresh-cut vegetable, and provided certain scientific basis for further study. (authors)