Date of Award
Master of Science
Food Science and Technology
John R Mount
P. Michael Davidson, F. Ann Draughon
Americans consume 28 lbs of ground beef annually. Beef can become contaminated with Salmonella during the initial slaughter process. Whole cuts of meat are ground into other products and the contamination spreads. This increases the risk of food borne illness for many Americans that consume ground beef products. The purpose of this study is to determine if adequate microbial destruction of Salmonella populations in ground beef of different fat levels can be achieved at temperatures that are lower than government guidelines.
Ground beef was inoculated with a four-strain mixture of Salmonella. Three fat levels of ground beef were used (10, 17, and 25% fat). Samples of ground beef (10g) were heated in a water bath to target temperatures of 60, 65.5, and 71.1°C. The heated samples were removed from the water bath at predetermined time intervals and cooled in an ice bath. Salmonella was enumerated on plate count agar (PCA). Serotype survival was also analyzed. The heat treatments significantly decreased bacteria populations (p < 0.05) and the 60, 65.6, and 71.1 °C heat treatments were significantly different from each other. The results indicate that fat level had no significant effect on bacterial survival (p > 0.05). Also, S. Senftenburg was found most often during longer exposure to heat treatment. Overall, the results indicate that combinations of heating at 60, 65.6 °C can achieve similar bacterial destruction as heating at 71.1 °C and should be considered by manufactures that use ground beef.
Williams, Christopher Jerome, "Survival of Salmonella Strains in Ground Beef Containing Varying Fat Contents and Heated at Varying Calculated Lethalities. " Master's Thesis, University of Tennessee, 2009.