Date of Award:

1996

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Nutrition, Dietetics, and Food Sciences

Advisor/Chair:

Von T. Mendenhall

Co-Advisor/Chair:

Jeff Broadbent

Third Advisor:

Charles E. Carpenter

Abstract

Sterile ceramic plates and the surface of beef steaks were inoculated with the pathogenic microorganisms Listeria monocytogenes, Campylobacter jejuni, Escherichia coli and Salmonella typhimurium. Samples were also inoculated with nonpathogenic microorganisms Clostridium sporogenes ATCC 7955, Pseudomonas aeruginosa, and Bacillus stearothermophilus. Concentrations of organisms in the pure culture used to inoculate the samples were selected within the range of 106 to 108 colony forming units/ml (CFU/ml). Samples were treated with ultra-high temperature (UHT), and· the surviving organisms were recovered and counted. Meat samples were exposed to 1100°C for 22 seconds.

Beef steaks inoculated with pathogenic microorganisms had low survival rates. The percent destruction ranged from 99.9 to 99.8. Sixteen percent of the spores from putrefactive anaerobe 3679 were destroyed. UHT was not found to be effective in destroying the spores of this organism. UHT destroyed 99.9 to 100 percent of the nonpathogenic microorganisms Pseudomonas and Bacillus stearothermophilus, respectively, inoculated on the surface of beef steaks prior to treatment. UHT pasteurization technology proved to be an effective method of controlling vegetative pathogens and vegetative spoilage organisms on meat surfaces.

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