Abstract: The effect of high oxygen modified atmosphere packaging on antioxidant activities in fresh-cut lettuce during storage was investigated in this paper. Lettuce slices were packaged in atmospheres with different oxygen contents, i.e., 60% O2+20% CO2+20% N2, 100% O2, or air as control, and stored at 4 ℃ for 14 days. The contents of vitamin C, polyphenols and carotenoids in fresh-cut lettuce and the abilities of these compound and lettuce juice to scavenge DPPH radicals were determined during storage. The results showed that antioxidant enzyme activities in fresh-cut lettuce were affected remarkably by high oxygen modified atmosphere packaging. High oxygen modified atmosphere packaging alleviated the decreases of vitamin C and β-carotenoids contents, and their DPPH scavenging capacities, and increased the content of total polyphenols and its DPPH free radical scavenging capacity. Statistical analysis showed a positive linear relationship between vitamin C content and antioxidant activity with a correlation coefficient of 0.8745. Therefore, high oxygen treatment alleviated the decrease of total antioxidant activity in fresh-cut lettuce, and this may be attributed to inhibiting the decrease of vitamin C.

Key words: fresh-cut lettuce, high oxygen modified atmosphere packaging, vitamin C, carotenoids, total polyphenols, antioxidant activity