Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/2/2005
Publication Date: 10/21/2005
Citation: Stabel, J.R., Lambertz, A. 2005. Efficacy of current Pasteurization Standards for the heat inactivation of Mycobacterium avium subsp. paratuberculosis in Ultra-high Temperature milk [abstract]. MOST, China-USDA Workshop on Agricultural Products Processing and Food Safety. p. 35.
Technical Abstract: Mycobacterium avium subsp. paratuberculosis, the causative agent of a chronic enteritis in ruminants (Johne’s disease), has been linked to Crohn’s disease in humans. This microorganism is shed primarily in the feces by infected animals but is also shed in the milk at much lower levels. Therefore, dairy products from infected animals may be one mode of transmission of this animal pathogen. This study was designed to evaluate the effectiveness of the holder and high-temperature short-time pasteurization (HTST) standards on the destruction of M. paratuberculosis. A total of 180 experiments were conducted in this study using a slug-flow pasteurizer unit and a laboratory scale pasteurizer unit. Ultra-high temperature milk (UHT) was inoculated at 2 levels, 10(8) and 10(5) cfu/ml, with 3 different field strains of M. paratuberculosis. Five different time/temperature combinations were evaluated: 62.7°C for 30 min; 65.5°C for 16 sec; 71.7°C for 15 sec; 71.7°C for 20 sec; and 74.4°C for 15 sec. Three replicates of each experiment were run for the pasteurizer unit, time/temperature, and strain of M. paratuberculosis. Treatment of milk regardless of bacterial strain or pasteurizer unit resulted in an average 5.0 and 7.7 log(10) kill, respectively, for the low and high level of inoculum. Milk treated for cheese production (65.5°C/16 sec) resulted in a much lower and more variable kill. Results from this study indicate that the current US standards for batch and HTST pasteurization are effective in significantly reducing the survivability of M. paratuberculosis in milk. Short Biography Dr. J. R. Stabel, a Research Microbiologist, is Lead Scientist of the Understanding Host Pathogen Interactions for the Diagnosis and Control of Johne's Disease (Paratuberculosis) research project in the Bacterial Diseases of Livestock Research Unit at the USDA, Agricultural Research Service, National Animal Disease Center, Ames, IA. The research unit is concerned with conducting basic and applied research on the etiology, prevention and diagnosis of diseases of domestic animals caused by zoonotic bacterial agents. Research involves studies encompassing a variety of disciplines, including immunology, pathology, nutrition, endocrinology, bacteriology and molecular biology. She leads a project concerned with improving methods for identification of subclinical infection, elucidating pathogenic mechanisms including potential human health risks and developing safe and effective treatments for Mycobacterium paratuberculosis.