Sigmoidal thermal inactivation kinetics of Listeria innocua in broth: Influence of strain and growth phase

Miller, Fátima A.; Gil, Maria M.; Brandão, Teresa R. S.; Teixeira, Paula; Silva, Cristina L. M.

doi:10.1016/j.foodcont.2009.03.007

Cited by 35 publications

(20 citation statements)

References 26 publications

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“…In the work of Miller et al [31], the assumed dependent variable was the logarithm of the normalized values of the microbial load, log(N/N 0 ). The symmetric about the x-axis of the original Gompertz equation for growth (i.e.…”

Section: Modifications Of the Gompertz Model To Describe Inactivationmentioning

confidence: 99%

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On the Use of the Gompertz Model to Predict Microbial Thermal Inactivation Under Isothermal and Non-Isothermal Conditions

et al. 2011

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Food processes should be designed to provide an adequate margin of safety against microbiological risk of food poisoning and food spoilage throughout shelf life. In this field, the use of mathematical models that describe the microorganisms' kinetics in such conditions is an important tool for convenient design, control and optimization of efficient processes. If those models are accurate and precise, one can extract the best aiming at predictive purposes. The Gompertz equation is commonly applied to describe sigmoidal kinetics. Besides the proven adequacy of the model in those kinetics descriptions, most of the reported works do not use Gompertz equation in the most convenient form, and insightful information could be obtained with re-parameterized forms. This work aims at reviewing the use of the Gompertz model to describe inactivation, as well as re-parameterized forms that include parameters related to the survival curve features. Microbial survival often presents a shoulder prior to inactivation, followed by a linear phase (corresponding to a maximum inactivation rate) and a tail residual population. The versatility of the Gompertz model in describing kinetics with different shapes, varying from a log-linear tendency till a complete sigmoidal shape, makes it attractive for predictive purposes, both under static and dynamic temperature conditions. Drawbacks and critical features of the model, when it is applied to microbial responses, will be overview.

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Section: Modifications Of the Gompertz Model To Describe Inactivationmentioning

confidence: 99%

“…Listeria innocua thermal inactivation data in broth under isothermal conditions were considered at temperatures of 52.5, 55.0, 57.5, 60.0, 62.5 and 65.0°C (data from [31]. The three functions that can be used for inactivation (Table 1) were fitted to experimental data by nonlinear regression analysis.…”

Section: A Case Studymentioning

confidence: 99%

On the Use of the Gompertz Model to Predict Microbial Thermal Inactivation Under Isothermal and Non-Isothermal Conditions

et al. 2011

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“…The non-isothermal inactivation processes studies were compared to an isothermal treatment, at which the temperature was maintained at 65 C (Miller et al, 2009). At a constant temperature of 65 C, Listeria suffered a 5-log cycles reduction in approximately 2.5 min.…”

Section: Resultsmentioning

confidence: 99%

“…This cell growth phase was chosen due to its higher stress resistance than exponential phase cells (Miller, Gil, Brandão, Teixeira, & Silva, 2009). Cells in each cellular suspension were enumerated by plating appropriate dilutions, in duplicate, on the three solid media studied.…”

Section: Preparation Of Culturesmentioning

confidence: 99%

Heat inactivation of Listeria innocua in broth and food products under non-isothermal conditions

et al. 2011

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a b s t r a c tThe objective of this work was to study the effect of three linear temperature profiles (heating rates of 1.5, 1.8 and 2.6 C/min, from 20 to 65 C) on Listeria innocua inactivation in liquid medium. The inactivation was also analyzed in artificially contaminated parsley (heating rate of 1.8 C/min) and throughout a frying process, using a pre-cooked frozen food as case study. Inactivation showed a sigmoidal behaviour and all data was fitted with a Gompertz-inspired model. Results demonstrated that, in liquid media, Listeria inactivation is influenced by the temperature profile used. As heating rate increases, the shoulder decreases and the tail effect disappears. If Listeria was in parsley, its heat resistance increased (for identical experimental conditions in broth). Besides model adequacy was proven in all studied situations, the heating rate affected parameters' precision.

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“…The second subculture of L. innocua was incubated at 30°C for ±24 h to yield stationary phase cultures. This cell growth phase was chosen, because the stress resistance of L. innocua cells is higher in that phase, in comparison with the lag or exponential phases (Miller et al 2009). …”

Section: Microbial Analysismentioning

confidence: 99%

Study on Thermosonication and Ultraviolet Radiation Processes as an Alternative to Blanching for Some Fruits and Vegetables

Alexandre

Santos-Pedro

Brandão

et al. 2011

Food Bioprocess Technol

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The impacts of ultraviolet-C radiation, blanching by heat, and combination of heat/ultrasounds (thermosonication) were studied for Listeria innocua (inoculated) in red bell peppers, total mesophiles in strawberries and total coliforms in watercress, in the temperature range 50-65°C. Quality attributes such as colour and firmness were studied for all products, and total anthocyanins content was additionally determined for strawberries. Results showed that ultraviolet-C radiation was the least effective treatment in terms of microbial load reduction and was equivalent to a simple water washing. Log reductions were 1.05±0.52 for L. innocua, 0.53±0.25 for total coliforms and 0.26±0.18 for total mesophiles. This treatment had the lowest impact on the quality parameters analysed. Thermosonication treatment was similar to heat blanching for all microorganism/product tested, excepted for total coliforms in watercress at 65°C, in which thermosonication had a higher effect (p<0.05). Heat blanching at 65°C allowed 7.43±0.12 log-cycles reduction, while loads were diminished by 8.24±0.13 log-cycles if thermosonication at the same temperature was applied. Thermosonication also allowed better quality retention, when compared to heat blanching at the same temperatures. The impact of thermosonication on microbial load reductions was statistically significant and thermosonicated samples retained quality attributes better than heat blanched ones at the same temperatures (p<0.05). Hence, it can be concluded that thermosonication is a promising process and may be a favourable alternative to the conventional thermal treatments.

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Sigmoidal thermal inactivation kinetics of Listeria innocua in broth: Influence of strain and growth phase

Cited by 35 publications

References 26 publications

On the Use of the Gompertz Model to Predict Microbial Thermal Inactivation Under Isothermal and Non-Isothermal Conditions

On the Use of the Gompertz Model to Predict Microbial Thermal Inactivation Under Isothermal and Non-Isothermal Conditions

Heat inactivation of Listeria innocua in broth and food products under non-isothermal conditions

Study on Thermosonication and Ultraviolet Radiation Processes as an Alternative to Blanching for Some Fruits and Vegetables

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