Salmonella heat resistance

McDonough, F.E. and Hargrove, R.E. 1968. Heat resistance of Salmonella in dried milk. Journal of Dairy Science 51 1587-1591. 

In many research and regulatory cases, data descriptive of a specimen must be associated or coordinated with the descriptions of the strains isolated from the specimens. Some common specimen data are exemplified by "total" microbial population, numbers of special groups of organisms such as coliforms, heat resistant bacteria, halophiles, psychrophiles, etc., the presence or absence of certain organisms (e.g.. Salmonella), incubation media, incubation conditions, geographic location of the specimen, physical and chemical condition of the specimen at the time of accession, and conditions of isolation of microbial strains from the specimen. 

Heat has been widely applied to destroy salmonellae in various food products. The thermal pasteurisation of whole egg, reviewed by Cunningham, is specifically based on the inactivation of 10 to 10 salmonellae (of normal heat resistance) per gramme of product, and is a legal requirement in many countries including United Kingdom (64°C for 2-5 min) China (63 °C for 2 5 min) Australia... 

Water activity a ) is another environmental characteristic which markedly influences the heat resistance of salmonellae , and this is particularly important in the processing of chocolate, as reviewed by... 

Hernandez, J. T. (1978). Heat Resistance of Salmonellae in Fresh Beef Meat. M.Sc. Thesis. University of Reading. 

Bactericidal processes which can be most effectively and practically used to eliminate salmonellae from foods appear to be mainly limited to the application of heat or of irradiation. As discussed by Mossel and Ley , ionising radiation is particularly technically attractive with its highly penetrative biocidal properties and because it can uniquely be used to terminally pasteurise previously frozen or packaged food products. On the theoretical basis of reducing the population of salmonellae by a factor of 10, i.e. 6 log cycles, the most probable effective dose (MPED) has been estimatedto be 0-4 0-2 Mrad (4 0 2 0kGy) and 0-25 Mrad has been shown to inactivate at least 3 log cycles of salmonellae on deep-frozen boiler carcasses under simulated commercial conditions A cautionary note was introduced by Urbain in 1978, however, who considers that salmonellae radicidation may be uneconomic unless universally required by government legislation and Davies Sinskey have shown that radiation-resistant mutants of S. typhimurium potentially exist and can be selectively isolated in extreme, cyclic irradiation circumstances. 

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