Effects of Sodium Tripolyphosphate and Modified Atmosphere Packaging on the Quality Characteristics and Storage Stability of Ground Beef

The effect of sodium tripolyphosphate (STP; 0.25 and 0.50% by mass), modified atmosphere packaging (MAP; 80% O-2+20% CO2), and storage time (14 days) on the colour, lipid stability and microbial growth during storage ((2.0 +/- 0.5) degrees C) of ground beef was studied. During storage, total aerobic mesophilic, psychrotrophic, lactic acid bacteria, Pseudomonas sp. and Enterobacteriaceae sp. counts, thiobarbituric acid reactive substances (TBARS) and colour values of ground beef were determined. There was significant (p<0.01) difference in the microbial counts in ground beef among the treatment groups. The lowest mesophilic, psychrotrophic bacteria and Pseudomonas counts were determined in the 0.25% STP+MAP group. Compared to aerobic control, the number of Pseudomonas was decreased approx. 2 log units in all other treatment groups. Other than MAP alone, 0.50% STP+MAP resulted in a significant reduction of lipid oxidation of ground beef. The red colour value a* of STP+MAP groups was more stable than that of aerobic and MAP controls. The values of a* (redness) and b* (yellowness) of the external surface of ground beef were higher than those of the internal surface. Using only MAP with high O-2 is unsuitable for ground beef because it increases lipid oxidation. Thus, the quality of ground beef can be protected using STP and MAP with 80% O-2+20% CO2.