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Fish are highly susceptible to spoilage from postmortem microbial growth and chemical deterioration, which and lead to a short shelf life and severe economic loss. In recent years, application of modified atmosphere packaging(MAP) technology to seafood has received widespread attention to delay spoilage and extend the shelf life. The purposes of this research were to investigate the effect of CO2 level, temperature, gas mixtures, carbon monoxide (CO) mixture on the quality of fresh tilapia fillets and to find an optimal modified atmosphere condition for fresh tilapia fillets. The results demonstrated that increased the higher CO2 level and the lower temperature are more effective for bacterial growth inhibition. But when CO2 level higher than 60%, increased drip loss, discoloration and pack collapse were observed. The microbial (total aerobic counts, total psychrotrophic counts, total coliform counts ) and chemical (pH, Drip, VBN, TBA) changes were no significantly different among fresh tilapia fillets stored in defferent gas mixtures (O2/CO2, N2/CO2, CO/CO2) of MAP at 0 ℃. The Hunter b/a value increased with discoloration, it could be a reliable index of color changeing for tilapia fillets. The residual CO level was correlated with the levels of CO and CO/O2 gas filling time. The CO residue decreased to 4.39ppm after 7 days storage in CO/O2 treated tilapia fillets with CO/O2 gas (ratio 1:99)for 30 min at 0℃. For the above results, optimal MAP condition for tilapia fillets was treated CO/O2=1/99 gas treated for 30 min at 0℃, then packaged in high-barrier film under MAP of N2/CO2=4/6 and stored at 0℃. The fillets treated with this condition had a prolonged shelf life and a stable, cherry-red color. The shelf life of fresh tilapia under MAP could be extend to 19 days longer than fillets packaged under Air and VP. The appearance, fish odor and overall acceptability of tilapia fillets treated with MAP was better than Air and VP treatment by sensory evaluation.
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