Heat sensitivity of Mycobacterium avium ssp. paratuberculosis in milk under pilot plant pasteurization conditions

• Published in: International journal of dairy technology 2007-05, Vol.60 (2), p.98-104
• Main Authors: LYNCH, DAVID, JORDAN, KIERAN N, KELLY, PHILLIP M, FREYNE, THOMAS, MURPHY, PATRICK M
• Format: Article
• Language: English
• Subjects: bacterial contamination; Biological and medical sciences; food contamination; Food engineering; Food industries; food microbiology; Fundamental and applied biological sciences. Psychology; General aspects; Heat sensitivity; heat tolerance; homogenization; Milk and cheese industries. Ice creams; Mycobacterium avium; Mycobacterium avium paratuberculosis; Mycobacterium avium subsp. paratuberculosis; pasteurization; pasteurizers; Pilot plant pasteurizer; raw milk; strain differences; strains; temperature; turbulent flow
• ISSN: 1364-727X; 1471-0307
• DOI: 10.1111/j.1471-0307.2007.00317.x

Raw cow's milk inoculated with four laboratory strains (10²-10⁵ cfu/mL) of Mycobacterium avium ssp. paratuberculosis (Map) was pasteurized in a custom designed pilot plant pasteurizer having a maximum throughput of 580 L/h under turbulent flow conditions. Following 16 pasteurizer trials none of the Map strains survived high-temperature short-time conditions (72.5°C x 27 s) whether milk was homogenized or not. Two dairy herds containing animals which were faecal positive for Map were sourced and milk was collected for pasteurization studies. Milk collected from one herd on five occasions in the autumn did not contain any detectable Map organisms, and the second herd that was sampled on only one occasion in early winter was shown to contain Map at low concentration. Map was not detected in any of these milks following pasteurization at 72.5°C for 27 s. Two natural isolates of Map inoculated into milk were likewise inactivated on pasteurization.