Abstract: In order to investigate the effect of modified atmospheres with varying carbon dioxide levels on the preservation of chilled chicken, chilled chicken was inoculated with 103 CFU/g Pseudomonas fluorescent after sterilization by irradiation, packaged in different modified atmospheres: M1 group ((V(CO2):V(N2) = 20:80), M2 group ((V(CO2):V(N2) = 20:80), M3 group ((V(CO2):V(N2) = 40:60) and M4 group ((V(CO2):V(N2) = 60:40) and then stored at (4 ± 1) ℃. Normal air package was used as control. Changes in the degree of concavity, P. fluorescent count, pH, total volatile basic nitrogen (TVB-N) and putrescine content were measured during storage. Results showed that P. fluorescent count, TVB-N and putrescine content increased with increasing storage time, whereas they decreased with increasing CO2 level. The degree of concavity increased with increasing storage time or CO2 level; the degree of concavity in group M4 was significantly higher than that in other groups (P < 0.05), impacting the visual appearance of chicken. No difference in the degree of concavity or putrescine content was observed comparing groups M2 and M3 (P > 0.05). Similarly, no difference in TVB-N content was found from the ninth day to the twelfth day of storage (P > 0.05). Thus, an identical preservation effect was achieved. However, CO2 is more expensive than N2 of the same volume. Overall, we concluded that modified atmospheres containing 20%–40% of CO2 could strongly inhibit the growth of P. fluorescent in chilled chicken under the storage of (4 ± 1) ℃.

Key words: chilled chicken, modified atmosphere packaging, carbon dioxide, shelf-life, Pseudomonas fluorescent