Estimating the survival of Clostridium botulinum spores during heat treatments

• Published in: Journal of food protection Vol. 63; no. 2; pp. 190 - 195
• Main Authors: PELEG, M, COLE, M. B
• Format: Journal Article
• Language: English
• Published: Des Moines, IA International Association of Milk, Food and Environmental Sanitarians 01.02.2000
• Subjects: Biological and medical sciences; Clostridium botulinum - physiology; Computer Simulation; Food industries; Food microbiology; Fundamental and applied biological sciences. Psychology; General aspects; Hot Temperature; Methods of analysis, processing and quality control, regulation, standards; Spores, Bacterial - physiology; Performance evaluation; Clostridium botulinum; Microbiological testing; Clostridiales; Temperature effect; Experimental study; Inactivation; Forecast model; Spores; Clostridiaceae; Pathogen strain; Sterilization; Bacteria; Mathematical model; Contaminant; Industrial technology
• ISSN: 0362-028X; 1944-9097
• DOI: 10.4315/0362-028X-63.2.190

A recently published study of the inactivation of Clostridium botulinum spores at various temperatures in the range of 101 to 121 degrees C and neutral pH revealed that their semilogarithmic survival curves all had considerable upward concavity. This finding indicated that heat inactivation of the spores under these conditions did not follow a first-order kinetics and that meaningful D values could not be calculated. The individual survival curves could be described by the cumulative form of the Weibull distribution, i.e., by log S = -b(T)t(n(T)), where S is the survival ratio and b(T) and n(T) are temperature-dependent coefficients. The fact that at all temperatures in the above range n(T) was smaller than 1 suggested that as time increases sensitive members of the population parish and survivors with increasing resistance remain. If damage accumulation is not a main factor, and the inactivation is path independent, then survival curves under monotonously increasing temperature can be constructed using a relatively simple model, which can be used to calculate the spores' survival in a limiting case. This is demonstrated with computer-simulated heating curves and the experimental constants of the C. botulinum spores, setting the number of decades reduction to 8, 10, and 12 (the current criterion for commercial sterility).