Influence of low oxygen concentrations on color stability of modified atmosphere packaged beef

Abstract

The influence of low oxygen concentrations on the development of color and the myoglobin redox states over storage time was analyzed, to determine whether there are conditions that increase discoloration. Beef slices were packaged in atmospheres containing nitrogen gas and 0 %, 0.5 %, 1 %, 1.5 %, 3 %, and 5 % of oxygen. The samples were stored at 2 °C for 14 days. During storage, color, reflectance and oxygen concentration were measured optically through the packaging. The color difference ΔE2000 and the relative oxymyoglobin (OMb), deoxymyoglobin (DMb), and metmyoglobin (MMb) levels were calculated. After 14 days, the oxygen concentrations changed to 0.09 % (0 %), 0.36 % (0.5 %), 0.92 % (1 %), 1.28 % (1.5 %) 2.55 % (3 %), and 4.29 % (5 %). Regarding MMb formation, the 0 % samples (ΔMMb0–14d 11.1 %) were significantly (p < 0.05) more stable compared to the other samples, which showed an increase of MMb formation with rising oxygen concentration after 14 days. The other samples reached a ΔMMb0–14d increase of 21.1 % (0.5 %), 26.7 % (1 %), 30.0 % (1.5 %), 31.1 % (3 %), and 34.4 % (5 %). The color stability showed significantly (p < 0.05) increasing ΔE values of 2.49 (0 %), 3.39 (0.5 %), 4.66 (1 %), 5.14 (1.5 %), 6.03 (3 %), and 7.34 (5 %) with rising oxygen contents. These findings suggest that to ensure the color stability of beef with minimal MMb formation, it is important to completely exclude oxygen from the packages, since the destabilizing effect of oxygen already started at 0.5 %. The non-invasive measurement of the oxygen concentration and the reflectance data over 14 days gave new insights into the discoloration process of beef stored in low-oxygen atmospheres.