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United States Department of Agriculture

Agricultural Research Service

Title: The Efficiency of Conventional Pasterurization Temperatures on Bacillus Anthracis (Sterne) Spores in Water, Media, and Milk

item Novak, John
item Call, Jeffrey
item Wallace, Frederick
item Tomasula, Peggy
item Luchansky, John

Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: February 1, 2004
Publication Date: August 12, 2004
Citation: Novak, J.S., Call, J.E., Wallace, F.M., Tomasula, P.M., Luchansky, J.B. 2004. The efficiency of conventional pasterurization temperatures on Bacillus anthracis (Sterne) spores in water, media, and milk [Abstract]. International Association for Food Protection Annual Meeting. P167.

Technical Abstract: Although the likelihood of natural contamination of milk with B. anthracis from infected animals is small, there is potential for purposeful addition of spores to bulk milk exceeding 1,000,000 spores/ml. High temperature-short time (HTST) pasteurization at the legal minimum time and temperature condition (72oC for 15 sec), or at higher temperatures and longer times (78oC for 30 sec), or at ultra-high temperature pasteurization (130oC for 1-2 sec) have been successful in reducing levels of vegetative cells of pathogens in milk, but may be ineffective against heat resistant spores. The decimal reduction times (D-values) for B. anthracis (Sterne) spores inoculated to 1,000,000,00 spores/ml in dH2O, brain heart infusion (BHI) broth, or skim milk (SM) were calculated at these pasteurization temperatures. Pasteurization at 72oC was ineffective (< 1log10 CFU/ml reduction) in reducing spore viability for B. anthracis (Sterne) in all 3 test fluids for treatments up to 90 min. The D values at 78 C were estimated at 115.4 + 32.3 min for spores in dH2O, 612.9 + 431.5 min for spores in BHI, and 640.3 + 513.3 min for spores in SM. As evidenced by D values at 130C of 0.7 + 0.2 min for spores in dH2O, 0.9 + 0.3 min for spores in BHI, and 1.1 + 0.1 min for spores in SM, respectively, ultra-high pasteurization conditions were also found to be inadequate for inactivating spores. In related studies, spores from B. cereus ATCC strains 14579 and 9818, representative aerobic spore-forming bacteria found in milk, were similar to B. anthracis (Sterne) in their thermal resistance.

Last Modified: 4/22/2015
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