Color stability of ground beef packaged in a low carbon monoxide atmosphere or vacuum

Ground beef was either packaged in an atmosphere of 0.4% CO, 30% CO₂, and 69.6% N₂ (CO-MAP) or vacuum. After storage (48 h, 2–3 °C), packages of CO-MAP and vacuum were opened and overwrapped with polyvinyl chloride. Other CO-MAP and vacuum packages were left intact. Packages were initially displayed for 7 days (2–3 °C). Intact packages were further displayed up to 35 days before being opened and displayed (1 or 3 days). Intact CO-MAP packaged ground beef was always more red than intact vacuum-packaged ground beef. Color was relatively stable for both types of intact packages over 35 days of display. Upon opening CO-MAP packaged ground beef, the red color decreased slower than in ground beef from vacuum packages.