The highest decreases were found in 1:1 headspace packaged samples, in accordance with their higher counts of lactic acid bacteria. Meat pH can be affected by many factors; however, growth of lactic acid bacteria resulting in lactic acid production is the major factor causing pH decreases in packaged meats (Gill, 1996). Lower pH values at 10 days were found in the air and N2 packaged samples which would support lactic acid bacteria outgrowth. Similarly, Coventry et al. (1998) reported that steaks in O2–CO2 atmospheres showed a relatively constant pH (5.5–5.6) compared with those in N2–CO2 atmospheres stored at 4 °C which exhibited significant (Pb0.01) decreases in pH (b5.0 after 2– 6 weeks).