Effects of intensity and processing time of 254 nm UV irradiation on Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella Typhimurium were investigated. Intensities measured at 5.08, 10.1, 15.2, and 20.3 cm from the light source were 1.000, 500, 250, and 150 microW/cm2, respectively. Intensities of 250 or 500 microW/cm2 reduced all suspended pathogen cells in peptone water about 5 log cycles after 2 min and completely inactivated L. monocytogenes and E. coli O157:H7 after 3 min by reductions of 8.39 and 8.64 log cycles, respectively. Intensities of 250 or 500 microW/cm2 also reduced (P < or = 0.05) the tested pathogens inoculated on stainless steel (SS) chips, and E. coli O157:H7 was completely destroyed at 500 microW/cm2 for 3 min. After UV treatment for 3 min at 500 microW/cm2, all selected pathogens on chicken meat with or without skin showed reduction ranges from 0.36 to 1.28 log cycles. Results demonstrated that UV irradiation could effectively decrease pathogens in peptone water and on SS but that it was less effective on chicken meat.

Chicken carcasses from 7-wk-old birds were skinned, deboned by hand, and the meat ground twice through a meat grinder. Samples were divided into 90-g portions, packaged, and stored at 3 C. The pH, cooking yield, and color of raw and cooked ground chicken meat were determined at 4-day intervals during 28 days of storage. In addition, ground meat samples were brought to pH values ranging from 4.9 to 7.1 by treating with citric acid or Na3PC»4. Chicken fillets were marinated in suspensions that contained citric acid and Na3PC»4 for color evaluation. Increased refrigerated storage time increased (P < .05) the pH of ground chicken meat. As ground meat pH increased, Hunter Lab "L" and "a" values decreased (P < .05). After samples were cooked, both internal and external Hunter Lab "L" and "b" values decreased (P < .05) and "a" increased (P < .05) as storage time progressed. Results indicated that raw and cooked chicken meat color were related to pH values and the color of raw and cooked chicken fillets can be altered with marinades containing citric acid and Na3PC»4. (

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Handdeboned raw broiler meat was ground through a meat grinder and adjusted to pH valueswf approximately 3,5,7, and 9. The prepared samples along with the controls were covered and stored at 2-4°C. The 2-thiobarbituric acid (TBA) values of the samples were measured immediately after sample preparation and during refrigeration storage for a period of 14 days. The pH values affected the lipid oxidation of ground raw meat as measured by the TBA test. The lower the pH values, the stronger pro-oxidant affect. Adjusting the pH values of ground raw poultry meat to neutral or alkaline slowed the increase in TBA values.

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