Effect of turbulent-flow pasteurization on survival of Mycobacterium avium subsp. paratuberculosis added to raw milk

A pilot-scale pasteurizer operating under validated turbulent flow (Reynolds number, 11,050) was used to study the heat sensitivity of Mycobacterium avium subsp. paratuberculosis added to raw milk. The ATCC 19698 type strain, ATCC 43015 (Linda, human isolate), and three bovine isolates were heated i...

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Published in:Applied and environmental microbiology 2001-09, Vol.67 (9), p.3964-3969
Main Authors: PEARCE, Lindsay E, TUAN TRUONG, H, CRAWFORD, Robert A, YATES, Gary F, CAVAIGNAC, Sonia, DE LISLE, Geoffrey W
Format: Article
Language:English
Subjects:
Animals
Bacteria
Biological and medical sciences
Cattle
Culture Media
Food industries
Food Microbiology
Fundamental and applied biological sciences. Psychology
Heat
Hot Temperature
Humans
Microbiology
Milk
Milk - microbiology
Milk and cheese industries. Ice creams
Mycobacterium avium
Mycobacterium avium subsp. paratuberculosis - growth & development
Mycobacterium avium subsp. paratuberculosis - isolation & purification
Pasteurization
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Summary:A pilot-scale pasteurizer operating under validated turbulent flow (Reynolds number, 11,050) was used to study the heat sensitivity of Mycobacterium avium subsp. paratuberculosis added to raw milk. The ATCC 19698 type strain, ATCC 43015 (Linda, human isolate), and three bovine isolates were heated in raw whole milk for 15 s at 63, 66, 69, and 72 degrees C in duplicate trials. No strains survived at 72 degrees C for 15 s; and only one strain survived at 69 degrees C. Means of pooled D values (decimal reduction times) at 63 and 66 degrees C were 15.0 +/- 2.8 s (95% confidence interval) and 5.9 +/- 0.7 s (95% confidence interval), respectively. The mean extrapolated D72 degrees C was 7 log10 kill at 72 degrees C for 15 s (95% confidence interval). The mean Z value (degrees required for the decimal reduction time to traverse one log cycle) was 8.6 degrees C. These five strains showed similar survival whether recovery was on Herrold's egg yolk medium containing mycobactin or by a radiometric culture method (BACTEC). Milk was inoculated with fresh fecal material from a high-level fecal shedder with clinical Johne's disease. After heating at 72 degrees C for 15 s, the minimum M. avium subsp. paratuberculosis kill was >4 log10. Properly maintained and operated equipment should ensure the absence of viable M. avium subsp. paratuberculosis in retail milk and other pasteurized dairy products. An additional safeguard is the widespread commercial practice of pasteurizing 1.5 to 2 degrees above 72 degrees C.
ISSN:0099-2240
1098-5336
DOI:10.1128/AEM.67.9.3964-3969.2001