Influence of dietary vitamin E on behavior of Listeria monocytogenes and color stability in ground turkey breast meat following electron beam irradiation
There is growing concern that the free radical scavenging effect of antioxidants added to meats might reduce the antimicrobial effectiveness of ionizing radiation. A study was conducted to determine the effect of vitamin E on the behavior of Listeria monocytogenes and color stability in turkey meat following electron beam irradiation. Raw ground turkey breast meat from birds fed diets containing 0 (control), 50, 100, and 200 IU of vitamin E per kg was inoculated with a 5-strain mixture of L. monocytogenes to give [difference]107 CFU/g. Inoculated samples were irradiated at 0, 0.5, 1, and 2 kGy, and stored aerobically (12 days) or under vacuum (42 days) at 4C̊. L. monocytogenes survivors were determined by plating diluted samples on Modified Oxford Medium (MOX) and counting bacterial colonies on MOX plates after 48h at 35C̊. Meat color was measured using a Hunter Lab colorimeter. Irradiation at 2.0 kGy resulted in [difference]3.5 log reduction of initial numbers of L. monocytogenes. There were no significant differences in D-values for L. monocytogenes in meat irrespective of vitamin E treatment (P>0.05). Also, vitamin E treatments did not affect growth rate of the pathogen in aerobic or vacuum-packaged samples following irradiation (P>0.05). Compared to controls, irradiated meat from birds fed 100 or 200 IU vitamin E demonstrated significant improvement in color stability (Hunter L* and a*-values) during aerobic storage (P<0.05). Dietary vitamin E (100 to 200 IU) has good potential for improving the color stability of turkey meat without compromising the microbial safety of the irradiated product.