UV-C irradiation inhibits surface discoloration and delays quality degradation of fresh-cut stem lettuce

The deterioration of surface color is a major factor limiting the marketability of fresh-cut stem lettuce. In this study, the impact of UV-C irradiation on fresh-cut stem lettuce was investigated. Slices were exposed to different doses (0, 1, 4, 8 or 12 kJ m(-2)) of UV-C light, then stored at 4 degrees C for 6 d. It was observed that all UV-C treatments could retard the occurrence of surface green fading and browning, and 8 kJ m(-2) was determined as the optimal dose which used for further evaluation. Results showed that UV-C treatment decreased the degradation of chlorophyll, the loss of ascorbic acid (AsA) and the accumulation of phenolic compounds. Moreover, UV-C treatment did not show a distinct effect on activities of PPO and POD, but pronouncedly inhibited the activity of PAL. Based on this, the inhibited tissue browning upon application of UV-C should be mainly attributed to suppressed PAL activity. Additionally, the aroma data indicated that storage time was the main contributor to the changes of volatile components, whereas the impact of UV-C treatment was limited, especially in the first 4 d. These findings suggest that UV-C treatment has a potential practical application in preserving fresh-cut stem lettuce.

Automated summary

UV-C treatment can delay the occurrence of surface green fading and browning in fresh-cut stem lettuce, with 8 kJ m(-2) being the optimal dose. It also reduces the degradation of chlorophyll, loss of ascorbic acid (AsA), and accumulation of phenolic compounds. UV-C treatment has potential practical application in preserving fresh-cut stem lettuce.