Effects of modified gas atmosphere packaging on pork loin colour, display life and drip loss

Boneless loins from both sides of 20 pig carcasses were divided into five sections each and assigned equally to five packaging treatments: 100 % CO 2 ; 50 % CO 2 /50 % N 2 ; 25 % CO 2 / 75 % N 2 ; 25 % CO 2 /65 % N 2 /10 % O 2 and vacuum. Loin sections were packaged in bags of low O 2 permeability, then stored in darkness at 1 °C for up to 22 days. Retail chops were cut from the sections and displayed in oxygen-permeable film under light at 3 °C for 3 additional days. The O 2 concentrations in packages with nominally anoxic atmospheres were 0.1–0.4 %. Sections stored in 25 % CO 2 /65 % N 2 /10 % O 2 had more surface greying and greening, stronger off-odour and psychrotropic counts after storage were more than one log 10 higher compared to sections from the other four treatments. Displayed chops from sections stored in 25 % CO 2 /65 % N 2 /10 % O 2 also had greying/greening at an outer layer of the chops. Off-odour of chops was most pronounced for treatments with 10 % O 2 and vacuum. Drip loss from loin sections was highest for those in 100 % CO 2 (4.2 %) and lowest for those in vacuum (3.2 %). In conclusion, storage in CO 2 or CO 2 N 2 atmospheres benefitted the overall shelf life of pork.