Effect of Dietary and Irradiation Interventions on the Pathogen Reduction and Quality of Turkey Meat

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Vitamin E is an essential nutrient that enhances the immunity of stressed animals and also is an excellent defense against cellular damage by free radicals. The protective effect of vitamin E on the oxidation of lipids and color change in raw meat is closely related to the antioxidant potential of muscle tissues. Dietary vitamin E increased plasma and tissue vitamin E levels, improved color stability, and reduced total volatile production and oxidative changes in raw meat during storage. Vitamin E also enhanced CD4 and CD8 lymphocytes and enhanced clearance of L. monocytogenes from experimentally infected turkeys. Selenium is essential for activity of glutathione peroxidase that improves antioxidant defense mechanisms and possesses immuno-stimulating properties. Supplementing the diet with selenium is crucial to maintain efficient neutrophil activity, the main defense mechanism against pathogenic bacteria. Conjugated linoleic acid (CLA) reduces fat deposition and has potent immune modulation activities characterized by increased lymphocyte blastogenesis. In addition, dietary CLA changed the fatty acid composition of meat and influenced volatile production and storage stability of meat. Irradiation is an effective technology for inactivating food-borne pathogens and improving the microbial safety of foods. The bacteriocidal action of ionizing irradiation is largely linked to damage of bacterial DNA from the production of free radicals during the irradiation process. The extent of cellular damage can be compromised by the presence of antioxidants such as vitamin E and the selenium-containing enzyme -- glutathione peroxidase. In addition to inactivating bacteria, the production of free radicals and the depletion of antioxidants in muscle by irradiation could reduce the storage stability and increase the production of off-odor volatiles in meat. The increase of vitamin E, selenium, and CLA in muscle tissues by dietary supplementation may protect meats from quality changes during irradiation and storage. This protective antioxidant effect of vitamin E in meat, however, may compromise the bacteriocidal effect of irradiation by scavenging free radicals, and thus, increase the survival of pathogenic bacteria during the irradiation process. Considering the involvement of free radicals on the initiation of lipid oxidation-dependent off-odor production, the use of antioxidants in irradiated meat to control off-odor production is highly reasonable. In light of recent outbreaks and product recalls due to pathogenic bacteria in meat, the expanded application of irradiation technology to meat products becomes especially important. However, the effectiveness of irradiation is limited if the quality of irradiated meat is not acceptable. Irradiated meats produce a characteristic aroma, which can negatively impact consumer acceptance. Understanding the effect of dietary antioxidants on the production of off-odor volatiles and consumer acceptance will provide information necessary to minimize the negative effects of irradiation on meat quality, which will be vital for the meat industry as it implements irradiation technology.
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The major research objective of the Food Safety Program is developing strategies to control, eliminate, or prevent disease-causing microorganisms in foods. Poultry meat, including turkey, is among the major causes of food borne diseases. Therefore, developing strategies to control pathogenic microorganisms and maintain high sensory quality in turkey meat is important.
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We have prepared diets and placed the first 240 turkeys in Poultry farm December 2002. The birds will be slaughtered in April and used for microbial and quality study at the time. Turkeys for monitoring the effect of dietary vitamin E, selenium, conjugated linoleic acid (CLA), alone or in combination on the immune responses and the colonization of S. Typhimurium and C. jejuni, in live turkeys will be placed in January.
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The goal of this project is to develop strategies to control pathogenic microorganisms and maintain high sensory quality in turkey meat. The efforts listed above will allow us to develop practical reduction/elimination strategies to control food-borne pathogens in live turkeys and turkey meat while minimizing the negative effects of irradiation on desirable quality characteristics of turkey meat.