INFLUENCE OF GAMMA IRRADIATION DOSE RATE ON SOME QUALITY CHARACTERISTICS OF BEEF

Beef samples were exposed to 3 kGy gamma irradiation using 2 dose rates (high and low) then stored in a refrigerator at 4oC for 2 weeks. The effect of the dose rate was investigated on the microbiological quality, colour components (a-, b- and L-values), cooking loss, moisture and texture of beef. The results revealed that there was a significant (P<0.05) decrease in the mean psychrotrophic, mould and yeast, Pseudomonas spp. counts in samples irradiated with the low dose rate than those with the high dose rate. By refrigerated storage, the counts increased significantly (P<0.05). Although there was no difference in the a- were and L-values between the high and low dose rates, but there was a significant (P< 0.05) increase in the a-value and decrease in the L-value as compared with the control. No difference in the b-value was found between control and irradiated samples. Refrigerated storage resulted in a significant (P<0.05) reduction in the a- and b-values. Although moisture content was unaffected by irradiation, the cooking loss was decreased significantly (P<0.05) apart from the dose rate. Generally, it could be concluded that 3 kGy gamma irradiation at low dose rate had better influence on microbiological qualities of beef in comparison with the high dose rate