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Santiago Condón - One of the best experts on this subject based on the ideXlab platform.
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Predicting Microbial Heat Inactivation under Nonisothermal Treatments
Journal of food protection, 2007Co-Authors: Mounir Hassani, Santiago Condón, Rafael PagánAbstract:The aim of this study was to develop an equation that accurately predicts microbial heat inactivation under nonisothermal treatments at constantly rising heating rates (from 0.5 to 5°C/min) in media with different pH values (4.0 or 7.4). The survival curves of all bacteria (Enterococcus faecium, Escherichia coli, Listeria monocytogenes, Salmonella senftenberg 775W, Salmonella Typhimurium, and Staphylococcus aureus) tested under isothermal treatments were nearly linear. For the most heat-resistant microorganism (E. faecium), the estimated DT -values at pH 7.4 were at least 100 times those of the second most thermotolerant microorganism (Salmonella senftenberg 775W). The heat resistance of E. faecium was up to 30 times lower at pH 4.0 than at pH 7.4. However, E. faecium was still the most heat-resistant microorganism under nonisothermal treatments at both pH values. Inactivation under nonisothermal conditions was not accurately estimated from heat resistance parameters of isothermal treatments when microbia...
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Inactivation of Salmonella senftenberg 775W by ultrasonic waves under pressure at different water activities
International journal of food microbiology, 2006Co-Authors: Ignacio Álvarez, Pilar Mañas, R. Virto, Santiago CondónAbstract:Abstract The inactivation of Salmonella senftenberg 775W by ultrasonic waves (20 kHz, 117 μm) under pressure (175 kPa) treatments at sublethal (manosonication; MS) and lethal temperatures (manothermosonication; MTS) in media of different water activities has been investigated. Heat decimal reduction time values increased up to eighteen fold when the water activity was decreased from > 0.99 to 0.93 at 65 °C, but hardly increased the MS resistance. In reduced water activity media ( a w of 0.96 and 0.93) a synergistic lethal effect was observed between heat and ultrasound under pressure, being the inactivation rate of Salmonella senftenberg 775W three times faster than the expected additive rate considering an effect of both bacterial lethal processes. An empirical mathematical equation enabled to predict the D MS and D MTS values obtained at different temperatures and a w in the ranges investigated of Salmonella serovars and also the microbial level of inactivation due to the synergistic lethal effect of MTS treatments in media of reduced a w . This work could be useful for improving sanitation and preservation treatments of foods, especially those in which components protect microorganisms to heat.
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Low molecular weight milk whey components protect Salmonella senftenberg 775W against heat by a mechanism involving divalent cations
Journal of applied microbiology, 2001Co-Authors: Pilar Mañas, Rafael Pagán, F.j. Sala, Santiago CondónAbstract:Aims: To investigate which components of milk increase the heat resistance of Salmonella senftenberg 775W, and to explore the mechanisms that could be involved in this protective effect. Methods and Results: The heat resistance of Salm. senftenberg was determined in a specially designed resistometer in several heating media. The molecules responsible for the thermal protective effect of milk were in the protein fraction, even in the
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Inactivation of Salmonella Enteritidis, Salmonella Typhimurium, and Salmonella senftenberg by ultrasonic waves under pressure.
Journal of food protection, 2000Co-Authors: Pilar Mañas, Rafael Pagán, Javier Raso, F.j. Sala, Santiago CondónAbstract:The resistance of Salmonella Enteritidis (ATCC 13076), Salmonella Typhimurium (ATCC 13311), and Salmonella senftenberg 775W (ATCC 43845) to ultrasonic waves under pressure treatments, at sublethal (manosonication) and lethal temperatures (manothermosonication) in citrate-phosphate buffer and in liquid whole egg was investigated. The influence of treatment parameters on the inactivation rate of manosonication was also studied. Decimal reduction times (Dt) of Salmonella Enteritidis, Salmonella Typhimurium, and Salmonella senftenberg 775W corresponding to a heat treatment at 60 degrees C in pH 7 buffer and in liquid whole egg were 0.068, 0.12, and 1.0 min for buffer, and 0.12, 0.20, and 5.5 min for liquid whole egg. Those corresponding to a manosonication treatment (117 microns, 200 kPa, 40 degrees C) in both media were 0.73, 0.78, and 0.84 min, and 0.76, 0.84, and 1.4 min, respectively. When the amplitude of ultrasonic waves was increased linearly, the inactivation rate of manosonication increased exponentially. The inactivation rate also increased when pressure was raised. However, the magnitude of this increase was progressively smaller at higher pressures. The magnitude of the influence of the amplitude of ultrasonic waves and static pressure on the inactivation rate of manosonication was the same in the three serotypes investigated. Whereas a heat treatment at 60 degrees C only attained a 1/2-log cycle reduction in the number of Salmonella senftenberg 775W survivors, a manothermosonication treatment (117 microns and 200 kPa) at this temperature attained a 3-log cycle reduction.
Rafael Pagán - One of the best experts on this subject based on the ideXlab platform.
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Combination of pulsed electric fields, mild heat and essential oils as an alternative to the ultrapasteurization of liquid whole egg.
International journal of food microbiology, 2014Co-Authors: Laura Espina, Ignacio Álvarez, S Monfort, Diego García-gonzalo, Rafael PagánAbstract:Abstract The production of microbiologically safe liquid whole egg (LWE) by industrial ultrapasteurization is restricted by the high thermal sensitivity of LWE components. This research proposes an alternative treatment based on the application of pulsed electric fields (PEF) and mild heat, in the presence of natural essential oils (EOs) or their individual components (ICs). The obtained results indicate that the successive application of PEF (25 kV/ and 100 kJ/kg) followed by heat (60 °C during 3.5') to LWE added with 200 μL/L of lemon EO would reach 4 log 10 cycles of inactivation of Salmonella senftenberg 775 W and Listeria monocytogenes , when any of these barriers acting alone inactivated less than 1.5 log 10 cycles of either bacteria. Therefore, the synergism between lemon EO and the successive application of PEF and heat would provide a safety level similar to that of ultrapasteurization treatment for Salmonella senftenberg 775 W and L. monocytogenes , but at a lower temperature. To a lesser extent, synergism with the successive application of PEF and heat was also observed in the presence of 200 μL/L of carvacrol, citral, (+)-limonene, or mandarin EO, reaching about 3.5 log 10 cycles of inactivation in Salmonella senftenberg and 3.0 log 10 cycles in L. monocytogenes , respectively. A sensory test on LWE containing 200 μL/L of each additive in the form of omelets and sponge cakes revealed that this concentration of mandarin EO, lemon EO, or (+)-limonene did not decrease the sensory acceptability of the LWE-containing products, and lemon EO and mandarin EO even increased the hedonic acceptability of sponge cakes. In conclusion, this process could be applied in the food industry to obtain microbiologically safe LWE, which could be used to produce egg-based products without decreasing (and even increasing) their sensory appeal.
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Predicting Microbial Heat Inactivation under Nonisothermal Treatments
Journal of food protection, 2007Co-Authors: Mounir Hassani, Santiago Condón, Rafael PagánAbstract:The aim of this study was to develop an equation that accurately predicts microbial heat inactivation under nonisothermal treatments at constantly rising heating rates (from 0.5 to 5°C/min) in media with different pH values (4.0 or 7.4). The survival curves of all bacteria (Enterococcus faecium, Escherichia coli, Listeria monocytogenes, Salmonella senftenberg 775W, Salmonella Typhimurium, and Staphylococcus aureus) tested under isothermal treatments were nearly linear. For the most heat-resistant microorganism (E. faecium), the estimated DT -values at pH 7.4 were at least 100 times those of the second most thermotolerant microorganism (Salmonella senftenberg 775W). The heat resistance of E. faecium was up to 30 times lower at pH 4.0 than at pH 7.4. However, E. faecium was still the most heat-resistant microorganism under nonisothermal treatments at both pH values. Inactivation under nonisothermal conditions was not accurately estimated from heat resistance parameters of isothermal treatments when microbia...
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Survival of Salmonella senftenberg 775 W to current liquid whole egg pasteurization treatments
Food Microbiology, 2003Co-Authors: Pilar Mañas, Rafael Pagán, Ignacio Álvarez, Santiago Condón UsónAbstract:Abstract The effect of heat shocks at constant temperature (isothermal heat shocks) or at constantly raising temperatures (anisothermal heat shocks) on the thermotolerance in liquid whole egg of the heat-resistant strain Salmonella senftenberg 775 W was investigated. The thermotolerance of Salmonella senftenberg 775 W increased with isothermal shock temperature. The D 63°C in liquid whole egg raised from 1.2 to 3.1 min after 1 h of isothermal heat shock at 54°C. Anisothermal heating lag phases also increased the thermotolerance of S. senftenberg 775 W in liquid whole egg to a higher extent, the higher the final temperature reached. Heating rate did not affect the heat resistance of S. senftenberg along the isothermal phase. Industrial pasteurization treatment for liquid whole egg at 60°C for 3.5 min, 64°C for 2.5 min and 70°C for 1.5 min would only attain Salmonella strain.
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Low molecular weight milk whey components protect Salmonella senftenberg 775W against heat by a mechanism involving divalent cations
Journal of applied microbiology, 2001Co-Authors: Pilar Mañas, Rafael Pagán, F.j. Sala, Santiago CondónAbstract:Aims: To investigate which components of milk increase the heat resistance of Salmonella senftenberg 775W, and to explore the mechanisms that could be involved in this protective effect. Methods and Results: The heat resistance of Salm. senftenberg was determined in a specially designed resistometer in several heating media. The molecules responsible for the thermal protective effect of milk were in the protein fraction, even in the
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low molecular weight milk whey components protect Salmonella senftenberg 775w against heat by a mechanism involving divalent cations
Journal of Applied Microbiology, 2001Co-Authors: P Manas, Rafael Pagán, F.j. Sala, S CondonAbstract:Aims: To investigate which components of milk increase the heat resistance of Salmonella senftenberg 775W, and to explore the mechanisms that could be involved in this protective effect. Methods and Results: The heat resistance of Salm. senftenberg was determined in a specially designed resistometer in several heating media. The molecules responsible for the thermal protective effect of milk were in the protein fraction, even in the < 3000 Da ultrafiltrate. The protective effect was lost when whey was demineralized. The former protective effect was restored when calcium or magnesium was added. Milk components protected cell envelopes of Salm. senftenberg from heat damage. Conclusions: The protein fraction and divalent cations were responsible for the protective effect of milk. The whole protective effect on Salm. senftenberg was not the result of the addition of the protective effect of each component, but the result of a synergistic effect of some of them interacting. Significance and Impact of the Study: This work could be useful for improving food preservation and hygiene treatments. It also contributes to our knowledge of microbial physiology.
Pilar Mañas - One of the best experts on this subject based on the ideXlab platform.
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Inactivation of Salmonella senftenberg 775W by ultrasonic waves under pressure at different water activities
International journal of food microbiology, 2006Co-Authors: Ignacio Álvarez, Pilar Mañas, R. Virto, Santiago CondónAbstract:Abstract The inactivation of Salmonella senftenberg 775W by ultrasonic waves (20 kHz, 117 μm) under pressure (175 kPa) treatments at sublethal (manosonication; MS) and lethal temperatures (manothermosonication; MTS) in media of different water activities has been investigated. Heat decimal reduction time values increased up to eighteen fold when the water activity was decreased from > 0.99 to 0.93 at 65 °C, but hardly increased the MS resistance. In reduced water activity media ( a w of 0.96 and 0.93) a synergistic lethal effect was observed between heat and ultrasound under pressure, being the inactivation rate of Salmonella senftenberg 775W three times faster than the expected additive rate considering an effect of both bacterial lethal processes. An empirical mathematical equation enabled to predict the D MS and D MTS values obtained at different temperatures and a w in the ranges investigated of Salmonella serovars and also the microbial level of inactivation due to the synergistic lethal effect of MTS treatments in media of reduced a w . This work could be useful for improving sanitation and preservation treatments of foods, especially those in which components protect microorganisms to heat.
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Survival of Salmonella senftenberg 775 W to current liquid whole egg pasteurization treatments
Food Microbiology, 2003Co-Authors: Pilar Mañas, Rafael Pagán, Ignacio Álvarez, Santiago Condón UsónAbstract:Abstract The effect of heat shocks at constant temperature (isothermal heat shocks) or at constantly raising temperatures (anisothermal heat shocks) on the thermotolerance in liquid whole egg of the heat-resistant strain Salmonella senftenberg 775 W was investigated. The thermotolerance of Salmonella senftenberg 775 W increased with isothermal shock temperature. The D 63°C in liquid whole egg raised from 1.2 to 3.1 min after 1 h of isothermal heat shock at 54°C. Anisothermal heating lag phases also increased the thermotolerance of S. senftenberg 775 W in liquid whole egg to a higher extent, the higher the final temperature reached. Heating rate did not affect the heat resistance of S. senftenberg along the isothermal phase. Industrial pasteurization treatment for liquid whole egg at 60°C for 3.5 min, 64°C for 2.5 min and 70°C for 1.5 min would only attain Salmonella strain.
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Low molecular weight milk whey components protect Salmonella senftenberg 775W against heat by a mechanism involving divalent cations
Journal of applied microbiology, 2001Co-Authors: Pilar Mañas, Rafael Pagán, F.j. Sala, Santiago CondónAbstract:Aims: To investigate which components of milk increase the heat resistance of Salmonella senftenberg 775W, and to explore the mechanisms that could be involved in this protective effect. Methods and Results: The heat resistance of Salm. senftenberg was determined in a specially designed resistometer in several heating media. The molecules responsible for the thermal protective effect of milk were in the protein fraction, even in the
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Inactivation of Salmonella Enteritidis, Salmonella Typhimurium, and Salmonella senftenberg by ultrasonic waves under pressure.
Journal of food protection, 2000Co-Authors: Pilar Mañas, Rafael Pagán, Javier Raso, F.j. Sala, Santiago CondónAbstract:The resistance of Salmonella Enteritidis (ATCC 13076), Salmonella Typhimurium (ATCC 13311), and Salmonella senftenberg 775W (ATCC 43845) to ultrasonic waves under pressure treatments, at sublethal (manosonication) and lethal temperatures (manothermosonication) in citrate-phosphate buffer and in liquid whole egg was investigated. The influence of treatment parameters on the inactivation rate of manosonication was also studied. Decimal reduction times (Dt) of Salmonella Enteritidis, Salmonella Typhimurium, and Salmonella senftenberg 775W corresponding to a heat treatment at 60 degrees C in pH 7 buffer and in liquid whole egg were 0.068, 0.12, and 1.0 min for buffer, and 0.12, 0.20, and 5.5 min for liquid whole egg. Those corresponding to a manosonication treatment (117 microns, 200 kPa, 40 degrees C) in both media were 0.73, 0.78, and 0.84 min, and 0.76, 0.84, and 1.4 min, respectively. When the amplitude of ultrasonic waves was increased linearly, the inactivation rate of manosonication increased exponentially. The inactivation rate also increased when pressure was raised. However, the magnitude of this increase was progressively smaller at higher pressures. The magnitude of the influence of the amplitude of ultrasonic waves and static pressure on the inactivation rate of manosonication was the same in the three serotypes investigated. Whereas a heat treatment at 60 degrees C only attained a 1/2-log cycle reduction in the number of Salmonella senftenberg 775W survivors, a manothermosonication treatment (117 microns and 200 kPa) at this temperature attained a 3-log cycle reduction.
S Condon - One of the best experts on this subject based on the ideXlab platform.
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Liquid Whole Egg Ultrapasteurization by Combination of PEF, Heat, and Additives
Food and Bioprocess Technology, 2013Co-Authors: S Monfort, S Condon, J Raso, N. Sagarzazu, I AlvarezAbstract:This paper evaluates the possibilities of combined processes based on the successive application of pulsed electric fields (PEF) and heat, in the presence of additives (EDTA and triethyl citrate (TC)), as an alternative to liquid whole egg (LWE) industrial ultrapasteurization. Firstly, the lethality of the combined processes on two heat-resistant microorganisms ( Salmonella senftenberg 775W and Listeria monocytogenes ) was evaluated. Secondly, the impact of these processes on LWE physicochemical and functional properties was determined. In the best-case scenario, the application of PEF (25 kV/cm; 200 kJ/kg) followed by heat (60 °C/3.5 min) to LWE added with 10 mM EDTA or 1 % TC inactivated around 5-Log_10 cycles of Salmonella senftenberg 775W and L. monocytogenes , while industrial ultrapasteurization (70–71 °C/1.5 min) provided 3.5–5.0-Log_10 reductions of both microorganisms. LWE treated by the combined processes was less viscous, showed better foaming and emulsifying properties, and formed more mouthfeel gels than the ultrapasteurized product. On the other hand, LWE treated by the combined process in the presence of TC increased by 90 % the foaming stability, and the treated in the presence of EDTA improved by 10 % the emulsifying capacity of non-treated LWE, whereas thermal ultrapasteurization dramatically reduced both properties. Therefore, the application of PEF (25 kV/cm; 200 kJ/kg) followed by heat (60 °C/3.5 min) in the presence of 1 % TC or 10 mM EDTA could be promising alternatives to the industrial ultrapasteurization since similar or even higher safety level with a lower impact on LWE quality was obtained.
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low molecular weight milk whey components protect Salmonella senftenberg 775w against heat by a mechanism involving divalent cations
Journal of Applied Microbiology, 2001Co-Authors: P Manas, Rafael Pagán, F.j. Sala, S CondonAbstract:Aims: To investigate which components of milk increase the heat resistance of Salmonella senftenberg 775W, and to explore the mechanisms that could be involved in this protective effect. Methods and Results: The heat resistance of Salm. senftenberg was determined in a specially designed resistometer in several heating media. The molecules responsible for the thermal protective effect of milk were in the protein fraction, even in the < 3000 Da ultrafiltrate. The protective effect was lost when whey was demineralized. The former protective effect was restored when calcium or magnesium was added. Milk components protected cell envelopes of Salm. senftenberg from heat damage. Conclusions: The protein fraction and divalent cations were responsible for the protective effect of milk. The whole protective effect on Salm. senftenberg was not the result of the addition of the protective effect of each component, but the result of a synergistic effect of some of them interacting. Significance and Impact of the Study: This work could be useful for improving food preservation and hygiene treatments. It also contributes to our knowledge of microbial physiology.
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predicting inactivation of Salmonella senftenberg by pulsed electric fields
Innovative Food Science and Emerging Technologies, 2000Co-Authors: Javier Raso, Ignacio Álvarez, S Condon, Francisco Sala J TrepatAbstract:Abstract Pulsed electric field inactivation of Salmonella senftenberg suspended in McIlvaine buffer of pH 7 and conductivity 2 mS/cm was investigated. In this study, square wave waveform pulses were used. After the same treatment time, inactivation of S. senftenberg depended neither on pulse width (1–15 μs) nor frequency of treatment (1–5 Hz). Survivor curves of S. senftenberg at different electric field strengths did not follow first-order kinetics. These survival curves were described by the log-logistic model proposed by Cole et al. [Cole, M. B., Davies, K. W., Munro, G., Holyoak, C. D., and Kilsby, D. C. (1993). A vitalistic model to describe the thermal inactivation of Listeria monocytogenes . Journal of Industrial Microbiology , 12 , 232–239]. Comparison of measured and estimated values showed that this model accurately described the inactivation of S. senftenberg by high electric field pulses in the range of 12–28 kV/cm.
Ignacio Álvarez - One of the best experts on this subject based on the ideXlab platform.
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Combination of pulsed electric fields, mild heat and essential oils as an alternative to the ultrapasteurization of liquid whole egg.
International journal of food microbiology, 2014Co-Authors: Laura Espina, Ignacio Álvarez, S Monfort, Diego García-gonzalo, Rafael PagánAbstract:Abstract The production of microbiologically safe liquid whole egg (LWE) by industrial ultrapasteurization is restricted by the high thermal sensitivity of LWE components. This research proposes an alternative treatment based on the application of pulsed electric fields (PEF) and mild heat, in the presence of natural essential oils (EOs) or their individual components (ICs). The obtained results indicate that the successive application of PEF (25 kV/ and 100 kJ/kg) followed by heat (60 °C during 3.5') to LWE added with 200 μL/L of lemon EO would reach 4 log 10 cycles of inactivation of Salmonella senftenberg 775 W and Listeria monocytogenes , when any of these barriers acting alone inactivated less than 1.5 log 10 cycles of either bacteria. Therefore, the synergism between lemon EO and the successive application of PEF and heat would provide a safety level similar to that of ultrapasteurization treatment for Salmonella senftenberg 775 W and L. monocytogenes , but at a lower temperature. To a lesser extent, synergism with the successive application of PEF and heat was also observed in the presence of 200 μL/L of carvacrol, citral, (+)-limonene, or mandarin EO, reaching about 3.5 log 10 cycles of inactivation in Salmonella senftenberg and 3.0 log 10 cycles in L. monocytogenes , respectively. A sensory test on LWE containing 200 μL/L of each additive in the form of omelets and sponge cakes revealed that this concentration of mandarin EO, lemon EO, or (+)-limonene did not decrease the sensory acceptability of the LWE-containing products, and lemon EO and mandarin EO even increased the hedonic acceptability of sponge cakes. In conclusion, this process could be applied in the food industry to obtain microbiologically safe LWE, which could be used to produce egg-based products without decreasing (and even increasing) their sensory appeal.
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Inactivation of Salmonella Enteritidis and Salmonella senftenberg in Liquid Whole Egg Using Generally Recognized as Safe Additives, Ionizing Radiation, and Heat
Journal of food protection, 2007Co-Authors: Ignacio Álvarez, Brendan A. Niemira, Xuetong Fan, Christopher H. SommersAbstract:The effect of combining irradiation and heat (i.e., irradiation followed by heat [IR-H]) on Salmonella Enteritidis and Salmonella senftenberg inoculated into liquid whole egg (LWE) with added nisin, EDTA, sorbic acid, carvacrol, or combinations of these GRAS (generally recognized as safe) additives was investigated. Synergistic reductions of Salmonella populations were observed when LWE samples containing GRAS additives were treated by gamma radiation (0.3 and 1.0 kGy), heat (57 and 60 degrees C), or IR-H. The presence of additives reduced the initial radiation Dgamma -values (radiation doses required to eliminate 90% of the viable cells) by 1.2- to 1.5-fold, the thermal decimal reduction times (D,-values) by up to 3.5- and 1.8-fold at 57 and 60 degrees C, respectively, and the thermal D,-values after irradiation treatments by up to 3.4- and 1.5-fold at 57 and 60 degrees C, respectively, for both Salmonella serovars. Of all the additives investigated, nisin at a concentration of 100 IU/ml was the most effective at reducing the heat treatment times needed to obtain a 5-log reduction of Salmonella. Thus, while treatments of 21.6 min at 57 degrees C or of 5 min at 60 degrees C should be applied to achieve a 5-log reduction for Salmonella in LWE, only 5.5 min at 57 degrees C or 2.3 min at 60 degrees C after a 0.3-kGy radiation pretreatment was required when nisin at a concentration of 100 IU/ml was used. The synergistic reduction of Salmonella viability by IR-H treatments in the presence of GRAS additives could enable LWE producers to reduce the temperature or processing time of thermal treatments (current standards are 60'C for 3.5 min in the United States) or to increase the level of Salmonella inactivation.
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Inactivation of Salmonella serovars in liquid whole egg by heat following irradiation treatments.
Journal of food protection, 2006Co-Authors: Ignacio Álvarez, Brendan A. Niemira, Xuetong Fan, Christopher H. SommersAbstract:Salmonella is a frequent contaminant on eggs and is responsible for foodborne illnesses in humans. Ionizing radiation and thermal processing can be used to inactivate Salmonella in liquid whole egg, but when restricted to doses that do not affect egg quality, these technologies are only partially effective in reducing Salmonella populations. In this study, the effect of ionizing radiation in combination with thermal treatment on the survival of Salmonella serovars was investigated. Of the six Salmonella serovars tested, Salmonella senftenberg was the most resistant to radiation (Dγ = 0.65 kGy) and heat (D55°C = 11.31 min, z = 4.9°C). Irradiation followed by thermal treatment at 55 or 57°C improved the pasteurization process. Radiation doses as low as 0.1 kGy prior to thermal treatments synergistically reduced the D55°C and D57°C of Salmonella senftenberg 3.6- and 2.5-fold, respectively. The D55°C and D57°C of Salmonella Typhimurium were reduced 2- and 1.4-fold and those of Salmonella Enteritidis were redu...
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Inactivation of Salmonella senftenberg 775W by ultrasonic waves under pressure at different water activities
International journal of food microbiology, 2006Co-Authors: Ignacio Álvarez, Pilar Mañas, R. Virto, Santiago CondónAbstract:Abstract The inactivation of Salmonella senftenberg 775W by ultrasonic waves (20 kHz, 117 μm) under pressure (175 kPa) treatments at sublethal (manosonication; MS) and lethal temperatures (manothermosonication; MTS) in media of different water activities has been investigated. Heat decimal reduction time values increased up to eighteen fold when the water activity was decreased from > 0.99 to 0.93 at 65 °C, but hardly increased the MS resistance. In reduced water activity media ( a w of 0.96 and 0.93) a synergistic lethal effect was observed between heat and ultrasound under pressure, being the inactivation rate of Salmonella senftenberg 775W three times faster than the expected additive rate considering an effect of both bacterial lethal processes. An empirical mathematical equation enabled to predict the D MS and D MTS values obtained at different temperatures and a w in the ranges investigated of Salmonella serovars and also the microbial level of inactivation due to the synergistic lethal effect of MTS treatments in media of reduced a w . This work could be useful for improving sanitation and preservation treatments of foods, especially those in which components protect microorganisms to heat.
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Survival of Salmonella senftenberg 775 W to current liquid whole egg pasteurization treatments
Food Microbiology, 2003Co-Authors: Pilar Mañas, Rafael Pagán, Ignacio Álvarez, Santiago Condón UsónAbstract:Abstract The effect of heat shocks at constant temperature (isothermal heat shocks) or at constantly raising temperatures (anisothermal heat shocks) on the thermotolerance in liquid whole egg of the heat-resistant strain Salmonella senftenberg 775 W was investigated. The thermotolerance of Salmonella senftenberg 775 W increased with isothermal shock temperature. The D 63°C in liquid whole egg raised from 1.2 to 3.1 min after 1 h of isothermal heat shock at 54°C. Anisothermal heating lag phases also increased the thermotolerance of S. senftenberg 775 W in liquid whole egg to a higher extent, the higher the final temperature reached. Heating rate did not affect the heat resistance of S. senftenberg along the isothermal phase. Industrial pasteurization treatment for liquid whole egg at 60°C for 3.5 min, 64°C for 2.5 min and 70°C for 1.5 min would only attain Salmonella strain.
