Abstract: In this paper, the fresh-keeping effect of equilibrium modified atmosphere packaging (EMAP) conditions on quality parameters of Laiyang pears was explored. Results indicated that EMAP storage maintained a good level of fruit firmness, and inhibited the activity of polyphenol oxidase (PPO). After 120 days of the storage, the control group (without any packaging treatment) showed a PPO activity of 40.9 U/g, even higher than 28.4 U/g of the EMAP group, with a significant difference (P ＜ 0.05). EMAP treatment delayed the reduction in peroxidase (POD) activity and the increase in membrane permeability; the activity of POD in the EMAP group was 0.25 U/g, significantly higher than 0.04 U/g of the control group; and relative membrane permeability of EMAP-packaged pears was increased to a lower level after 120 days of the storage, with a smaller amplitude fluctuation over the entire storage period, and there was a extremely significant difference between the two groups (P ＜ 0.01). A reduction in vitamin C loss was observed for the EMAP group as compared to the control. After 30 days of the storage, the content of vitamin C in the EMAP group was higher than that in the control and the difference between them was exceedingly significant (P ＜ 0.01). The optimum gas composition for EMAP storage of Laiyang pears was found to be made up of 2.2% CO2 and 14.0% O2 or of 2.6% CO2 and 12.9% O2. The shelf life of Laiyang pears stored in two such atmospheric environments could reach up to more than 200 days.

Key words: Laiyang pear, quilibrium modified atmosphere packaging (EMAP), fresh-keeping