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K. Xanthiakos - One of the best experts on this subject based on the ideXlab platform.
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probabilistic model for listeria monocytogenes growth during distribution retail storage and domestic storage of Pasteurized Milk
Applied and Environmental Microbiology, 2010Co-Authors: Konstantinos P. Koutsoumanis, George-john E. Nychas, Athanasios Pavlis, K. XanthiakosAbstract:A survey on the time-temperature conditions of Pasteurized Milk in Greece during transportation to retail, retail storage, and domestic storage and handling was performed. The data derived from the survey were described with appropriate probability distributions and introduced into a growth model of Listeria monocytogenes in Pasteurized Milk which was appropriately modified for taking into account strain variability. Based on the above components, a probabilistic model was applied to evaluate the growth of L. monocytogenes during the chill chain of Pasteurized Milk using a Monte Carlo simulation. The model predicted that, in 44.8% of the Milk cartons released in the market, the pathogen will grow until the time of consumption. For these products the estimated mean total growth of L. monocytogenes during transportation, retail storage, and domestic storage was 0.93 log CFU, with 95th and 99th percentiles of 2.68 and 4.01 log CFU, respectively. Although based on EU regulation 2073/2005 Pasteurized Milk produced in Greece belongs to the category of products that do not allow the growth of L. monocytogenes due to a shelf life (defined by law) of 5 days, the above results show that this shelf life limit cannot prevent L. monocytogenes from growing under the current chill chain conditions. The predicted percentage of Milk cartons—initially contaminated with 1 cell/1-liter carton—in which the pathogen exceeds the safety criterion of 100 cells/ml at the time of consumption was 0.14%. The probabilistic model was used for an importance analysis of the chill chain factors, using rank order correlation, while selected intervention and shelf life increase scenarios were evaluated. The results showed that simple interventions, such as excluding the door shelf from the domestic storage of Pasteurized Milk, can effectively reduce the growth of the pathogen. The door shelf was found to be the warmest position in domestic refrigerators, and it was most frequently used by the consumers for domestic storage of Pasteurized Milk. Furthermore, the model predicted that a combination of this intervention with a decrease of the mean temperature of domestic refrigerators by 2°C may allow an extension of Pasteurized Milk shelf life from 5 to 7 days without affecting the current consumer exposure to L. monocytogenes.
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Dynamic modeling of Listeria monocytogenes growth in Pasteurized Milk
Journal of applied microbiology, 2006Co-Authors: K. Xanthiakos, Apostolos S. Angelidis, D. Simos, George-john E. Nychas, Konstantinos P. KoutsoumanisAbstract:Aims: The development and validation of a dynamic model for predicting Listeria monocytogenes growth in Pasteurized Milk stored at both static and dynamic temperature conditions. Methods and Results: Growth of inoculated L. monocytogenes in a commercial Pasteurized whole Milk product was monitored at various isothermal conditions from 1AE 5t o 16 � C. The kinetic parameters of the pathogen were modelled as a function of temperature using a square root type model, which was further validated using data from 92 published growth curves from eight different Milk products. Compared to four published models for L. monocytogenes growth, the model developed in this study performed better, with a per cent discrepancy and bias of 49AE1 and )1AE01%, respectively. The performance of the model in predicting growth at dynamic temperature conditions was evaluated at four different fluctuating temperature scenarios with periodic temperature changes from ) 2t o 16 � C. The prediction of growth at dynamic storage temperature was based on the square root model in conjunction with the differential equations of the Baranyi and Roberts model, which were numerically integrated with respect to time. The per cent relative errors between the observed and the predicted growth of L. monocytogenes were less than 10% for all temperature scenarios tested. Conclusions: Available models from experiments conducted in laboratory media may result in significant overestimation of L. monocytogenes growth in Pasteurized Milk because they do not take into account factors such as Milk composition (e.g. natural antimicrobial compounds present in Milk) and the interactions of the pathogen with the natural microflora. The product-targeted model developed in the present study showed a high performance in predicting growth of L. monocytogenes in Pasteurized Milk under both static and dynamic temperature conditions. Significance and Impact of the Study: Temperature fluctuations often occur during the transportation and storage of Pasteurized Milk. A high performance, dynamic model for the growth of L. monocytogenes can be a useful tool for effective management and optimization of product safety and can lead to more realistic estimations of Pasteurized-Milk related safety risks.
Konstantinos P. Koutsoumanis - One of the best experts on this subject based on the ideXlab platform.
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probabilistic model for listeria monocytogenes growth during distribution retail storage and domestic storage of Pasteurized Milk
Applied and Environmental Microbiology, 2010Co-Authors: Konstantinos P. Koutsoumanis, George-john E. Nychas, Athanasios Pavlis, K. XanthiakosAbstract:A survey on the time-temperature conditions of Pasteurized Milk in Greece during transportation to retail, retail storage, and domestic storage and handling was performed. The data derived from the survey were described with appropriate probability distributions and introduced into a growth model of Listeria monocytogenes in Pasteurized Milk which was appropriately modified for taking into account strain variability. Based on the above components, a probabilistic model was applied to evaluate the growth of L. monocytogenes during the chill chain of Pasteurized Milk using a Monte Carlo simulation. The model predicted that, in 44.8% of the Milk cartons released in the market, the pathogen will grow until the time of consumption. For these products the estimated mean total growth of L. monocytogenes during transportation, retail storage, and domestic storage was 0.93 log CFU, with 95th and 99th percentiles of 2.68 and 4.01 log CFU, respectively. Although based on EU regulation 2073/2005 Pasteurized Milk produced in Greece belongs to the category of products that do not allow the growth of L. monocytogenes due to a shelf life (defined by law) of 5 days, the above results show that this shelf life limit cannot prevent L. monocytogenes from growing under the current chill chain conditions. The predicted percentage of Milk cartons—initially contaminated with 1 cell/1-liter carton—in which the pathogen exceeds the safety criterion of 100 cells/ml at the time of consumption was 0.14%. The probabilistic model was used for an importance analysis of the chill chain factors, using rank order correlation, while selected intervention and shelf life increase scenarios were evaluated. The results showed that simple interventions, such as excluding the door shelf from the domestic storage of Pasteurized Milk, can effectively reduce the growth of the pathogen. The door shelf was found to be the warmest position in domestic refrigerators, and it was most frequently used by the consumers for domestic storage of Pasteurized Milk. Furthermore, the model predicted that a combination of this intervention with a decrease of the mean temperature of domestic refrigerators by 2°C may allow an extension of Pasteurized Milk shelf life from 5 to 7 days without affecting the current consumer exposure to L. monocytogenes.
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Dynamic modeling of Listeria monocytogenes growth in Pasteurized Milk
Journal of applied microbiology, 2006Co-Authors: K. Xanthiakos, Apostolos S. Angelidis, D. Simos, George-john E. Nychas, Konstantinos P. KoutsoumanisAbstract:Aims: The development and validation of a dynamic model for predicting Listeria monocytogenes growth in Pasteurized Milk stored at both static and dynamic temperature conditions. Methods and Results: Growth of inoculated L. monocytogenes in a commercial Pasteurized whole Milk product was monitored at various isothermal conditions from 1AE 5t o 16 � C. The kinetic parameters of the pathogen were modelled as a function of temperature using a square root type model, which was further validated using data from 92 published growth curves from eight different Milk products. Compared to four published models for L. monocytogenes growth, the model developed in this study performed better, with a per cent discrepancy and bias of 49AE1 and )1AE01%, respectively. The performance of the model in predicting growth at dynamic temperature conditions was evaluated at four different fluctuating temperature scenarios with periodic temperature changes from ) 2t o 16 � C. The prediction of growth at dynamic storage temperature was based on the square root model in conjunction with the differential equations of the Baranyi and Roberts model, which were numerically integrated with respect to time. The per cent relative errors between the observed and the predicted growth of L. monocytogenes were less than 10% for all temperature scenarios tested. Conclusions: Available models from experiments conducted in laboratory media may result in significant overestimation of L. monocytogenes growth in Pasteurized Milk because they do not take into account factors such as Milk composition (e.g. natural antimicrobial compounds present in Milk) and the interactions of the pathogen with the natural microflora. The product-targeted model developed in the present study showed a high performance in predicting growth of L. monocytogenes in Pasteurized Milk under both static and dynamic temperature conditions. Significance and Impact of the Study: Temperature fluctuations often occur during the transportation and storage of Pasteurized Milk. A high performance, dynamic model for the growth of L. monocytogenes can be a useful tool for effective management and optimization of product safety and can lead to more realistic estimations of Pasteurized-Milk related safety risks.
S B Lyss - One of the best experts on this subject based on the ideXlab platform.
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yersinia enterocolitica infections associated with improperly Pasteurized Milk products southwest pennsylvania march august 2011
Epidemiology and Infection, 2014Co-Authors: A H Longenberger, M P Gronostaj, G Y Yee, L M Johnson, J F Lando, R E Voorhees, Kirsten Waller, Andre Weltman, Maria Moll, S B LyssAbstract:In July 2011, a cluster of Yersinia enterocolitica infections was detected in southwestern Pennsylvania, USA. We investigated the outbreak's source and scope in order to prevent further transmission. Twenty-two persons were diagnosed with yersiniosis; 16 of whom reported consuming Pasteurized dairy products from dairy A. Pasteurized Milk and food samples were collected from this dairy. Y. enterocolitica was isolated from two products. Isolates from both food samples and available clinical isolates from nine dairy A consumers were indistinguishable by pulsed-field gel electrophoresis. Environmental and microbiological investigations were performed at dairy A and pasteurization deficiencies were noted. Because consumption of Pasteurized Milk is common and outbreaks have the potential to become large, public health interventions such as consumer advisories or closure of the dairy must be implemented quickly to prevent additional cases if epidemiological or laboratory evidence implicates Pasteurized Milk as the outbreak source.
Carlos Augusto Fernandes De Oliveira - One of the best experts on this subject based on the ideXlab platform.
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Microbiological Shelf Life of Pasteurized Milk in Bottle and Pouch
Journal of food science, 2010Co-Authors: Rodrigo Rodrigues Petrus, C.g. Loiola, Carlos Augusto Fernandes De OliveiraAbstract:Shelf life of Pasteurized Milk in Brazil ranges from 3 to 8 d, mainly due to poor cold chain conditions that prevail throughout the country and subject the product to repeated and/or severe temperature abuse. This study evaluated the influence of storage temperature on the microbiological stability of homogenized whole Pasteurized Milk (75 degrees C/15 s) packaged in high-density polyethylene (HDPE) bottle and low-density polyethylene (LDPE) pouch, both monolayer materials pigmented with titanium dioxide (TiO(2)). The storage temperatures investigated were 2, 4, 9, 14, and 16 degrees C. Microbiological evaluation was based on mesophilic and psychrotrophic counts with 7 log CFU/mL and 6 log CFU/mL, respectively, set as upper limits of acceptability for maintaining the quality of Milk. The microbiological stability for Pasteurized Milk packaged in HDPE bottle and stored at 2, 4, 9, 14, and 16 degrees C was estimated at 43, 36, 8, 5, and 3 d, respectively. For Milk samples packaged in LDPE pouch, shelf life was estimated at 37, 35, 7, 3, and 2 d, respectively. The determination of Q(10) and z values demonstrated that storage temperature has a greater influence on microbiological shelf life of Pasteurized Milk packaged in LDPE pouch compared to HDPE bottle. Based on the results of this study, HDPE bottle was better for storing Pasteurized Milk as compared to LDPE pouch.
Frank V. Kosikowski - One of the best experts on this subject based on the ideXlab platform.
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Flavor Development in Pasteurized Milk Blue Cheese by Animal and Microbial Lipase Preparations
Journal of Dairy Science, 2010Co-Authors: R.c. Jolly, Frank V. KosikowskiAbstract:This study is of rate and quality of flavor development and type and concentration of carbonyls produced in blue cheese made from Pasteurized Milk after applying selected microbial and animal enzyme preparations directly to cheese curds along with Penicillium roqueforti spores and salt. Two of 10 microbial lipase preparations (Aspergilli) gave good quality blue cheese flavor within 45 to 75 days at 5C in cheese made from Pasteurized Milk. Total carbonyls were maximum in 75 days at 5C and were highest in cheeses with added microbial lipase. Cheeses without added enzymes had lowest values and differed in the relative distribution of individual carbonyls. In cheese from 75-day-old Pasteurized Milk containing microbial lipase, at 5C the amount of 2-heptanone was 76.1μmol and 2-nonanone was 32.5μmol/10g cheese solids.