Modelling of inactivation of microorganisms in the process of sterilization using high pressure supercritical fluids (original) (raw)
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Food Control, 2013
This work evaluates the inactivation of Listeria monocytogenes through the use of supercritical carbon dioxide. For this purpose, the experimental design methodology was employed as a tool to assess the effects of temperature, depressurization rate, pressure cycling and the mass ratio of cell suspension to CO 2 . It was observed that the depressurization rate and mass of cell suspension to CO 2 ratio were statistically significant and inactivation kinetics was verified to be of first-order. It was also observed that the inactivation increased with increasing depressurization rates in the range of 6e12 MPa min À1 , keeping nearly constant above the upper value. The decimal reduction times ranged from 15.38 to 20.41 min. Results obtained in this work may be quite useful to the food industry committed to microorganism inactivation using the innovative supercritical carbon dioxide technology.
Comprehensive Reviews in Food Science and Food Safety
Formation of highly resistant spores is a concern for the safety of low-acid foods as they are a perfect vehicle for food spoilage and/or human infection. For spore inactivation, the strategy usually applied in the food industry is the intensification of traditional preservation methods to sterilization levels, which is often accompanied by decreases of nutritional and sensory properties. In order to overcome these unwanted side effects in food products, novel and emerging sterilization technologies are being developed, such as pressure-assisted thermal sterilization, high-pressure carbon dioxide, high-pressure homogenization, and cold plasma. In this review, the application of these emergent technologies is discussed, in order to understand the effects on bacterial spores and their inactivation and thus ensure food safety of low-acid foods. In general, the application of these novel technologies for inactivating spores is showing promising results. However, it is important to note that each technique has specific features that can be more suitable for a particular type of product. Thus, the most appropriate sterilization method for each product (and target microorganisms) should be assessed and carefully selected.
International Journal of Food Microbiology, 2007
Thermal pasteurization is a well known and old technique for reducing the microbial count of foods. Traditional thermal processing, however, can destroy heat-sensitive nutrients and food product qualities such as flavor, color and texture. For more than 2 decades now, the use of highpressure carbon dioxide (HPCD) has been proposed as an alternative cold pasteurization technique for foods. This method presents some fundamental advantages related to the mild conditions employed, particularly because it allows processing at much lower temperature than the ones used in thermal pasteurization. In spite of intensified research efforts the last couple of years, the HPCD preservation technique has not yet been implemented on a large scale by the food industry until now. This review presents a survey of published knowledge concerning the HPCD technique for microbial inactivation, and addresses issues of the technology such as the mechanism of carbon dioxide bactericidal action, the potential for inactivating vegetative cells and bacterial spores, and the regulatory hurdles which need to be overcome. In addition, the review also reflects on the opportunities and especially the current drawbacks of the HPCD technique for the food industry.
Bacterial inactivation on solid food matrices through supercritical CO2: A correlative study
Journal of Food Engineering, 2014
In this paper the effectiveness of dense phase carbon dioxide (DPCD) treatment to inactivate different bacterial strains inoculated on the surface of solid food matrices is studied. The bacterial survival is investigated on three distinct matrices: Salmonella enterica spiked on fresh cut coconut (Cocos nucifera), Escherichia coli on fresh cut carrot (Daucus carota) and Listeria monocytogenes on dry cured ham surface. Bacterial inactivation experiments are carried out in order to develop and identify mathematical models whose relative performance is assessed in terms of goodness-of-fit and a posteriori statistics obtained after parameters estimation. Operational maps illustrating the time required to achieve an assigned inactivation degree are built in order to guide the choice of the best operating conditions to be used in the process.
High-pressure supercritical carbon dioxide uses to inactivate Escherichia coli in pumpkin puree
Research, Society and Development, 2021
Coli ATCC 25922 inactivation was studied to determine the effect of high-pressure carbon dioxide (HPCD) process on pumpkin puree. Experiments were performed using a batch HPCD system at three conditions of pressure (7.5 MPa, 17.5 MPa and 27.5 MPa) at 32 °C. Afterwards, at the best experimental condition (27.5 MPa – 275 bar), a kinetic was performed to assess inactivation of microorganisms over time (from 1 to 8 h). The physicochemical characteristics (pH, total soluble solids – TSS, titratable acidity – TA, total carotenoids, total reducing sugars – TRS, moisture and optical microscopy) of the pumpkin puree were also evaluated. HPCD with acidification increases bacterial efficacy of treatments, as well as significant changes in physicochemical parameters. HPCD treatment reduced the microbial load moderately in all experiments, by a maximum of approximately 3.17 log cycles in 8 h of process at 27.5 MPa (275 bar). Optical microscopy showed no difference in cell wall, just in starch wh...
Thermal pasteurization is a well known and old technique for reducing the microbial count of foods. Traditional thermal processing, however, can destroy heat-sensitive nutrients and food product qualities such as flavor, color and texture. For more than 2 decades now, the use of highpressure carbon dioxide (HPCD) has been proposed as an alternative cold pasteurization technique for foods. This method presents some fundamental advantages related to the mild conditions employed, particularly because it allows processing at much lower temperature than the ones used in thermal pasteurization. In spite of intensified research efforts the last couple of years, the HPCD preservation technique has not yet been implemented on a large scale by the food industry until now. This review presents a survey of published knowledge concerning the HPCD technique for microbial inactivation, and addresses issues of the technology such as the mechanism of carbon dioxide bactericidal action, the potential for inactivating vegetative cells and bacterial spores, and the regulatory hurdles which need to be overcome. In addition, the review also reflects on the opportunities and especially the current drawbacks of the HPCD technique for the food industry.
Factors influencing death and injury of foodborne pathogens by hydrostatic pressure-pasteurization
Food Microbiology, 1998
The key objective of hydrostatic pressure-pasteurization of food is the destruction of pathogenic bacterial cells at a high level (8 log cycles) without adversely affecting the acceptance characteristics of a food. To achieve these goals, hydrostatic pressure-pasteurization may best be conducted at a moderate pressure, which alone will not kill the desired level of pathogens. However, along with hydrostatic pressure other parameters, namely pressurization-time, temperature and bactericidal compounds, such as bacteriocins, can be used to enhance bactericidal effects of pressurization. Our results with four pathogens indicated that viability loss at 25°C were minimal up to 207 MPa, then increased at a rapid rate. However, even above 483 MPa, not all species had 8 log cycles viability loss. At and above 276 MPa a large number of survivors were injured. At 207 MPa and 25°C, pressurization for 30 min did not greatly enhance viability loss and injury of the four pathogens. However, pressurization temperatures beyond 35°C greatly increased cell death and injury. By pressurizing the cells in the presence of a mixture of pediocin AcH and nisin viability loss of the pathogens was increased by an additional 1•3 to 5•1 log cycles. This increase was due to the bactericidal effect of the two bacteriocins on sensitive and injured cells. These results indicated that at moderate pressure, a high level of destruction of pathogens can be induced within a short time by using moderate temperature in combination with bactericidal preservative(s).
Journal of Food Science, 2008
Isobaric and isothermal semi-logarithmic survival curves of natural microflora in apple juice treated with high-pressure carbon dioxide at 7, 13, and 16 MPa pressures and 35, 50, and 60 degrees C temperatures were fitted with a nonlinear equation to find the values of the coefficient b(P), b(T), n(P), and n(T). Profiles of the model parameters were obtained as a function of pressure and temperature. The model fitted with good agreement(R(2) > 0.945), the survival curves. An empirical equation was proposed to describe the combined effects of pressure and temperature. The equation, derived from a power law model, was written in the form: log(10) S(t) = -log(e) [C(0)+C(1) x exp (K(T) x (T-T(C))-C(2) x exp (K(P) x (P-P(C))) x t (C(3)xT(2)+C(4)xT+C(5)). The proposed model fitted the experimental data well. At 7 MPa and 50 and 60 degrees C, 13 MPa and 35 and 60 degrees C, 16 MPa and 35 degrees C, the model provided (log)10 reduction residual values (observed value-fitted value) lower than 0.284 showing a good agreement between the experimental and the predicted survival levels.