Effect of Near Infrared Irradiation on Quality of Fresh-cut Lettuce During Storage

Abstract

The effect of near-infrared (NIR) irradiation before storage on the quality of fresh-cut lettuce was investigated in this study. It was shown that the NIR irradiation was effective in suppressing the number of viable bacteria and weight loss during the storage of cut lettuce, statistically. However, it was also shown that the browning ratio increased slightly under the stronger NIR irradiation conditions of the 30 s and 60 s, which could deteriorate the appearance quality. This was thought to be the result of increase in the Phenylalanine Ammonia Lyase (PAL) activity and total polyphenol content. Meanwhile, no increase in browning ratio was observed at 10 s, and there was no difference in PAL activity and total polyphenol content from the control. In the range of irradiation conditions set in this study, thus, the 10 s NIR irradiation was expected to be effective in suppressing the number of general viable bacteria and mass,