Color Changes in Radiation Pasteurized Beef

The effect of doses of gamma radiation varying from 0.1 to 1.5 Mrad applied to beef at 0°C on meat color was assessed by tristimulus colorimetry. Marked differences in redness and yellowness occurred among samples with the surface myoglobin in the reduced (Mb), oxygenated (Mb0₂) or oxidized (Mb+) state.

Irradiation of samples packaged in oxygen-permeable film (Vitafilm) resulted in a greater decrease in redness than irradiation of comparable samples packaged in oxygen-impermeable film (Saran). Samples packaged in Vitafilm and overwrapped in Saran prior to irradiation with O.S. Mrad retained the ability to reoxygenate after as long as 8 days post-irradiation storage at 4.4°C before removal of the outer wrap. No significant differences (P>0.05) in redness were noted among the unirradiated control samples at 0 days and samples from which the outer wrap was removed after 0, 2, 4, 6 or 8 days storage. The decrease in redness after removal of the outer wrap was not affected by time of storage.