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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Food Safety and Enteric Pathogens Research » Research » Publications at this Location » Publication #150994
Title: INFLUENCE OF DIETARY VITAMIN E ON BEHAVIOR OF LISTERIA MONOCYTOGENES AND COLOR STABILITY IN GROUND TURKEY MEAT FOLLOWING ELECTRON BEAM IRRADIATION

Author
item ROMERO, M - IOWA STATE UNIVERSITY
item MENDONCA, A - IOWA STATE UNIVERSITY
item AHN, D - IOWA STATE UNIVERSITY
item Wesley, Irene

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/8/2004
Publication Date: 6/20/2005
Citation: Romero, M.G., Mendonca, A.F., Ahn, D.U., Wesley, I.V. 2005. Influence of dietary Vitamin E on behavior of Listeria monocytogenes and color stability in ground turkey meat following electron beam irradiation. Journal of Food Protection. 68(6):1159-1164.

Interpretive Summary: Listeria monocytogenes is a major bacterial foodborne pathogen, which has been implicated in several outbreaks traced to contaminated dairy products and ready-to-eat meats, including turkey. Of all the bacterial foodborne pathogens, L. monocytogenes has the second highest case fatality rate (~ 20%) and the highest hospitalization rate (90%). Due to its relatively high fatality rate and the uncertainty of the infectious dose for immune compromised individuals, U.S. regulatory agencies established a "zero tolerance" for this pathogen in cooked and ready-to-eat foods. The elimination of this microorganism from foods by use of ionizing irradiation has been proposed. We analyzed the ability of vitamin E (50, 100, and 200 International Units) to neutralize the oxidizing effect of irradiation which not only kills bacterial pathogens but also alters meat color and therefore may jeopardize consumer acceptance of the irradiated product. In this study, vitamin E did not impair the ability of ionizing radiation to kill L. monocytogenes, as measured by D values. Compared to controls, irradiated meat from birds fed vitamin E (100 or 200 IU) showed significant improvement in color stability during aerobic storage (P < 0.05). Therefore, dietary vitamin E has good potential for improving the color stability of turkey meat without compromising the microbial safety of the irradiated product.

Technical Abstract: 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 ~10**7 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 4 deg C. L. monocytogenes survivors were determined by plating diluted samples on Modified Oxford Medium (MOX) and counting bacterial colonies on MOX plates after 48 h at 35 deg C. Meat color was measured using Hunter Lab colorimeter. Irradiation at 2.0 kGy resulted in approximately 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.