Kinetics of Heat Activation and of Thermal Death of Bacterial Spores

Shull, James J.; Cargo, G. T.; Ernst, Robert R.

doi:10.1128/aem.11.6.485-487.1963

Cited by 54 publications

(25 citation statements)

References 2 publications

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“…1 , 1988, 1992) is obtained from the Sapru model ( Fig. 1) by assuming that inactivation transformations D, and D2 have identical rate constants, i.e., K,,r = I& = I(d. The Shull model (Shull et al, 1963) obtained from the Sapru model by deleting D, (&r =0) and N3 and setting I<dt= I<d. Finally, the conventional model is obtained by deleting Nr,N,,Dr and A (I&r =&=), so that only Nm N2, De D,, and N, remain, and setting K., E I<dZ.…”

Section: Mathematical Modelsmentioning

confidence: 99%

“…Equations for isothermal responses N, and N, of the four models were obtained by analytical solution (Table 1). Note that the equation for N, of the Shull model is restricted to K, # I<d, when K, = &, a different equation applies (Shull et al, 1963) which is not of concern here. Survivor responses (N=NJ of all four models are in the general form N(t) = N*(t) = NZ,,e-'Qt + Cy,(l -e-Kt)e-rQt (5) where parameters C and K are functions of K,, I&i, and I&.…”

Section: Isothermal Response Equationsmentioning

confidence: 99%

“…Semilogarithmic plots of experimental survivor data often have deviated from a straight line (Stumbo, 1973). One deviation, a shoulder early in an exposure, occurs frequently with highly dormant and heat resistant spores of Bacillus stearothermophilus (Shull et al, 1963;Abraham et al 1990) It is attributed to activation of dormant spores and has been dealt with by either Authors Smerage and Teixeira are with the Dept. of Agricultural Engineering.…”

Section: Introductionmentioning

confidence: 99%

“…Among models including activation, considered sequential reactions for a population of B. stearothermophifus spores in which initially activated spores were destroyed immediately upon heating and initially dormant spores were activated and subsequently inactivited. Shull et. al.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of Predictive Models for Bacterial Spore Population Resources to Sterilization Temperatures

Sapru

Smerage

Teixeira

et al. 1993

Journal of Food Science

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Comparisons of characteristics of recent models and the conventional model of bacterial spore populations during thermal sterilization showed the conventional model was inadequate for general representation because it lacks activation of dormant spores. New models accounting for activation differed in other assumptions but obviated heat shock of indicator spores required when using the conventional model in validations of thermal sterilization. Comparisons of rate constants and simulated and experimental responses of models of B. stearothermophilus spores in constant and dynamic temperatures showed one new model was more general, more accurate and preferred. Arrhenius equations accurately described temperature dependencies of all rate constants of that model.

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Section: Mathematical Modelsmentioning

confidence: 99%

Section: Isothermal Response Equationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Comparison of Predictive Models for Bacterial Spore Population Resources to Sterilization Temperatures

Sapru

Smerage

Teixeira

et al. 1993

Journal of Food Science

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“…Recently survivor curves have recognized not necessarily obey first-order kinetics and to generally show shoulders, tails or downward and upward concavity (Shull et al 1963;Juneja and Marks 2005;Bialka et al 2008). The Weibull model (van Boekel 2002) has been reported to be a better fit for such nonlinear survivor curves.…”

Section: Discussionmentioning

confidence: 99%

Heat Resistance of G. Stearothermophilus and C. Sporogenes in Carrot and Meat Alginate Purees

Hassan¹,

Ramaswamy²

2011

Journal of Food Processing and Preservation

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The main objective of this study was to investigate the heat resistance of nonpathogenic, heat‐resistant Geobacillus stearothermophilus and Clostridium sporogenes spores in meat and carrot alginate purees. Alginate is used as a viscosity modifier in liquid foods and has been used to fabricate thermally stable and firm simulated particles for biological validation studies of thermal processing, when conventional temperature gathering is not possible. Pureed carrot and meat were mixed with sodium alginate and inoculated with high concentrations of spores of G. stearothermophilus or C. sporogenes and filled into capillary tubes, flame sealed and heat treated in an oil bath for different times at selected temperatures. D values were computed from the slopes of log(N/N0) versus time, and z values from log(D) versus temperature curves. For meat alginates, D values for G. stearothermophilus ranged between 1.9 min and 40.8 min with a z value of 11.7C and D values for C. sporogenes ranged between 0.9 min and 28.7 min with a z value of 10.1C. For carrot alginates, D values for G. stearothermophilus ranged between 1.9 min and 42.6 min with a z value of 11.5C and D values for C. sporogenes ranged from 1.1 min and 31.0 min with a z value of 10.2C. The results were also fitted to Weibull model, but the model did not result in any better fit than the conventional first‐order model. PRACTICAL APPLICATIONS Thermal process establishment is generally based on gathered time temperature data from test cans under real processing conditions. There are many situation like aseptic processing, continuous flow biaxial rotary processing, etc. in which such temperature measurements are often difficult. Biological validation is generally considered useful in such processes to validate the processes as well as computer simulations. Such concepts have been tried to some limited extent in the past. With new thermal processing equipment and processes surfacing time and again, such concepts need to be redesigned. In order to successfully use such applications, thermal destruction kinetics data under controlled conditions are needed. This study provides thermal destruction kinetics baseline data for one such study making use of alginate‐impregnated meat and carrot‐simulated particles. Further, the study compare two modeling procedures: the conventional first‐order log‐linear model versus the log‐nonlinear Weibull models.

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Sterile techniques

1965

Biotech & Bioengineering

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A new type of air filter was developed and tested in the pure culturing of aerobic microorganisms. 2, This filter was compounded from layers of porous poly(viny1 alcohol) (PVA). When compared with the traditional glass wool filters, the PVA filters achieved high collection efficiency with considerably less resistance to air flow. The PVA filters will withstand temperatures of 130°C. One difficulty in evaluating high efficiency filters has been to get accurate measurements of the efficiency. Several workersz0 have suggested the use of Escherichia coli bacteriophage T, as a possible test organism. By using phage, it is possible to reduce collection efficiencies to ranges that are measurable to obtain a value which is characteristic for the filter. This efficiency can be converted into a calculated efficiency for bacteria by multiplying by some factor depending on the sizes of the two types of particles.

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Kinetics of Heat Activation and of Thermal Death of Bacterial Spores

Cited by 54 publications

References 2 publications

Comparison of Predictive Models for Bacterial Spore Population Resources to Sterilization Temperatures

Comparison of Predictive Models for Bacterial Spore Population Resources to Sterilization Temperatures

Heat Resistance of G. Stearothermophilus and C. Sporogenes in Carrot and Meat Alginate Purees

Sterile techniques

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