Growth of Staphylococcus aureus on Beef Steaks as Influenced by Type of Packaging ^{1, 2}

Beef loin steaks were inoculated with 10⁵ cells of Staphylococcus aureus /cm² in two separate trials to determine the effects of different packaging treatments upon the organism's growth. Each trial utilized 72 samples which were randomly assigned to four packaging treatments: (1) over-wrapped in oxygen-permeable film; (2) vacuum packaged; (3) packaged in barrier bags flushed with a 60% CO₂ : 40% O₂ gas atmosphere then evacuated and sealed; and (4) packaged in barrier bags filled with a 60%CO₂ : 40% O₂ gas atmosphere. In each treatment group, 12 samples were inoculated with S. aureus while 6 were uninoculated and used as controls. All samples were displayed under simulated retail conditions at 10 C and enumerated for S. aureus after 3, 6 and 9 days. Numbers of S. aureus remained relatively constant for all treatments throughout the 9 day period. Results from a comparison of treatments for Trials I and II were variable; however, no significant treatment effects were found when data from both trials were pooled.