1887

Abstract

A plot of the thermal resistance of var. spores (log value) against temperature was linear between 37 and 190 °C ( = 23 °C), provided that the relative humidity of the spore environment was kept below a certain critical level. The corresponding plot for spores was linear in the range 150 to 180 °C ( = 29 °C) but departed from linearity at lower temperatures (decreasing value). However, the value of 29 °C was decreased to 23 °C if spores were dried before heat treatment. The straight line corresponding to this new value was consistent with the inactivation rate at a lower temperature (60 °C). The data indicate that bacterial spores which are treated in dry heat at an environmental relative humidity near zero are inactivated mainly by a drying process. By extrapolation of the thermal resistance plot obtained under these conditions for var. spores, the value at 0 °C would be about 4 years.

Loading

Article metrics loading...

/content/journal/micro/10.1099/00221287-101-2-227
1977-08-01
2024-10-11
Loading full text...

Full text loading...

/deliver/fulltext/micro/101/2/mic-101-2-227.html?itemId=/content/journal/micro/10.1099/00221287-101-2-227&mimeType=html&fmt=ahah

References

  1. Amaha M. 1953; Heat resistance of Cameron’s putrefactive anaerobe 3679 in phosphate buffer (Clostridium sporogenes). Food Research 18:411–420
    [Google Scholar]
  2. Angelotti R., Maryanski J. H., Butler T. F., Peeler J. T., Campbell J. E. 1968; Influence of spore moisture content on the dry-heat resistance of Bacillus subtilis var.niger.. Applied Microbiology 16:735–745
    [Google Scholar]
  3. Bigelow W. D. 1921; The logarithmic nature of thermal death time curves. Journal of Infectious Diseases 29:528–536
    [Google Scholar]
  4. Brannen J. P. 1970; An analysis of vacuum effects in the sterilization of microorganisms. Biophysik 7:55–59
    [Google Scholar]
  5. Brannen J. P., Garst D. M. 1972; Dry heat inactivation of Bacillus subtilis var.niger spores as a function of relative humidity. Applied Microbiology 23:1125–1130
    [Google Scholar]
  6. Edwards J. L. Jr Busta F. F., Speck M. L. 1965; Thermal inactivation characteristics of Bacillus subtilis spores at ultrahigh temperatures. Applied Microbiology 13:851–857
    [Google Scholar]
  7. Ernst R. R. 1968; Sterilization by heat. In Disinfection, Sterilization and Preservation pp. 703–740 Lawrence C. A., Block S. S. Edited by Philadelphia: Lea & Febiger;
    [Google Scholar]
  8. Esselen W. B., Pflug I. J. 1956; Thermal resistance of putrefactive anaerobe no. 3679 spores in vegetables in the temperature range of 250–290 °F. Food Technology 10:557–560
    [Google Scholar]
  9. Fox K., Pflug I. J. 1968; Effect of temperature and gas velocity on the dry-heat destruction rate of bacterial spores. Applied Microbiology 16:343–348
    [Google Scholar]
  10. Levine S. 1956; Determination of the thermal death rate of bacteria. Food Research 21:295–301
    [Google Scholar]
  11. Licciardello J. J., Nickerson J. T. R. 1963; Some observations on bacterial thermal death time curves. Applied Microbiology 11:476–479
    [Google Scholar]
  12. Marshall B. J., Murrell W. G., Scott W. J. 1963; The effect of water activity, solutes and temperature on the viability and heat resistance of freeze-dried bacterial spores. Journal of General Microbiology 31:451–460
    [Google Scholar]
  13. Molin G., Östlund K. 1975; Dry-heat inactivation of Bacillus subtilis spores by means of infra-red heating. Antonie van Leeuwenhoek 41:329–335
    [Google Scholar]
  14. Molin G., Östlund K. 1976; Dry-heat inactivation of Bacillus subtilis var.niger spores with special reference to spore density. Canadian Journal of Microbiology 22:359–363
    [Google Scholar]
  15. Murrell W. G., Scott W. J. 1966; The heat resistance of bacterial spores at various water activities. Journal of General Microbiology 43:414–425
    [Google Scholar]
  16. Oag R. K. 1940; The resistance of bacterial spores to dry heat. Journal of Pathology and Bacteriology 51:137–141
    [Google Scholar]
  17. Pflug I. J., Schmidt C. F. 1968; Thermal destruction of microorganisms. In Disinfection, Sterilization and Preservation pp. 63–105 Lawrence C. A., Block S. S. Edited by Philadelphia: Lea & Febiger;
    [Google Scholar]
  18. Pheil C. G., Pflug I. J., Nicholas R. C., Augustin J. A. L. 1967; Effect of various gas atmospheres on destruction of microorganisms in dry heat. Applied Microbiology 15:120–124
    [Google Scholar]
  19. Rahn O. 1945; Physical methods of sterilization of microorganisms. Bacteriological Reviews 9:1–47
    [Google Scholar]
  20. Rowe J. A., Silverman G. J. 1970; The absorption-desorption of water by bacterial spores and its relation to dry heat resistance. Developments in Industrial Microbiology 11:311–326
    [Google Scholar]
  21. Soper C. J., Davies D. J. G. 1971; The effect of high vacuum drying on the heat response of Bacillus megaterium spores. In Spore Research 1971 pp. 275–288 Barker A. N., Gould G. W., London J. Edited by Wolf and New York: Academic Press;
    [Google Scholar]
  22. Sykes G. 1965 Disinfection and Sterilization, 2nd edn.. London: Chapman and Hall;
    [Google Scholar]
  23. Wang D. I. C., Scharer J., Humphrey A. E. 1964; Kinetics of death of bacterial spores at elevated temperatures. Applied Microbiology 12:451–454
    [Google Scholar]
/content/journal/micro/10.1099/00221287-101-2-227
Loading
/content/journal/micro/10.1099/00221287-101-2-227
Loading

Data & Media loading...

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error