The Experts below are selected from a list of 558 Experts worldwide ranked by ideXlab platform
Tapani Alatossava - One of the best experts on this subject based on the ideXlab platform.
-
potential of Nitrogen Gas N2 flushing to extend the shelf life of cold stored pasteurised milk
International Journal of Molecular Sciences, 2013Co-Authors: Patricia Munschalatossava, Abdul Ghafar, Tapani AlatossavaAbstract:For different reasons, the amount of food loss for developing and developed countries is approximately equivalent. Altogether, these losses represent approximately 1/3 of the global food production. Significant amounts of pasteurised milk are lost due to bad smell and unpleasant taste. Currently, even under the best cold chain conditions, psychrotolerant spore-forming bacteria, some of which also harbour virulent factors, limit the shelf life of pasteurised milk. N2 Gas-based flushing has recently been of interest for improving the quality of raw milk. Here, we evaluated the possibility of addressing bacterial growth in pasteurised milk during cold storage at 6 °C and 8 °C. Clearly, the treatments hindered bacterial growth, in a laboratory setting, when N2-treated milk were compared to the corresponding controls, which suggests that N2-flushing treatment constitutes a promising option to extend the shelf life of pasteurised milk.
-
Improved Storage of Cold Raw Milk by Continuous Flushing of N2 Gas Separated from Compressed Air: A Pilot Scale Study
Journal of Food Processing and Technology, 2010Co-Authors: Patricia Munsch-alatossava, Oguz Gursoy, Tapani AlatossavaAbstract:Nitrogen Gas (N2) produced by a Gas generator unit from compressed air was continuously introduced in a tank of 170 L, that contained up to 110 L raw milk kept at 5.5±0.4 oC with an ice-water cooling unit. N2 Gas was introduced in the tank at a fixed flow rate ranging from 4 L to 14 L per min, whether flushed in the head space of the raw milk tank or bubbled directly into raw milk. In the tested conditions, the combination bubbling for 6 h followed by continuous flushing of N2, up to seven days, gave the best results, since the bacterial growth in raw milk could be retarded significantly. An increase of one log unit of the total bacteria required about 2.5-fold longer time under the N2 Gas flushing compared to the control (no N2 Gas treatment). The treatments also reduced phospholipases (PLs)-producing and Bacillus cereus type bacteria. The results obtained at a pilot plant scale demonstrate the potential of this technology, that could be applied in order to improve quality and safety of raw milk, during prolonged storage along the cold chain.
-
potential of Nitrogen Gas N2 to control psychrotrophs and mesophiles in raw milk
Microbiological Research, 2010Co-Authors: Patricia Munschalatossava, Oguz Gursoy, Tapani AlatossavaAbstract:Summary Pure N 2 Gas was introduced in the headspace of test bottles containing raw milk that were then stored at either 6.0, 7.0, or 12.0 °C. Treatment with N 2 significantly reduced the growth of total bacteria, and the growth of bacterial subgroups such as psychrotrophs, enterobacteria, protease- and lipase-producing bacteria, and Listeria spp, and completely excluded Bacillus cereus growth on MYP plates. The inhibitory effect was maximal at 6.0 °C, and bacterial growth could be halted at this temperature for 11 days. At 12.0 °C, N 2 was able to inhibit growth during the first 48 h. No alarming or undesirable effects, such as the excessive growth of anaerobes or lactobacilli, were observed during the course of the study. The same treatments also halted the growth of one bacterial isolate in pure culture that expressed multiresistance to antibiotics. The continuous flushing of raw milk with pure N 2 Gas in a so-called open system that allows Gas exchanges with the environment positively impacted the microbiological quality of the raw milk at a temperature range of 6.0–12.0 °C. This procedure should therefore be considered as a possible complementary method to refrigeration in controlling bacterial growth and the spoilage potential of both psychrotrophs and mesophiles in raw milk.
-
exclusion of phospholipases pls producing bacteria in raw milk flushed with Nitrogen Gas N2
Microbiological Research, 2010Co-Authors: Patricia Munschalatossava, Oguz Gursoy, Tapani AlatossavaAbstract:Summary Prolonged cold storage of raw milks favors the growth of psychrotrophs, which produce heat-resistant exoenzymes of considerable spoilage potential; the bacterial proteases and lipases affect raw milk quality; among them phospholipases (PLs) may target the milk fat globule. More importantly, bacterial PLs are key virulence factors for numerous species. Two studies examined the use of Nitrogen (N 2 ) Gas and examined its effect on psychrotrophs, proteases and lipase producers when the milk was stored in closed vessels; however, the effect on PLs producers is unknown. Here we show that by considering an open system the PLs producers were sooner or later excluded in raw milk (whereas the PLs producers in the non-treated controls culminated at 10 8 CFU/ml), by effective Gas treatments that bring oxygen (O 2 ) levels in milk lower than 0.1 ppm. No increase of the PLs producers among the anaerobes was noticed during the course of the experiments. In the experiments performed at 6.0 °C, the delay after which the PLs producers were no longer detectable seemed independent of the initial level of PLs producers in raw milk (lower than 10 3 CFU/ml). We anticipate that flushing pure N 2 Gas in raw milk tanks, considered as open systems, along the cold chain of raw milk storage and transportation, may be an additional technique to control psychrotrophs, and may also constitute an interesting perspective for limiting their spoilage and pathogenic potential in food materials in general.
Patricia Munschalatossava - One of the best experts on this subject based on the ideXlab platform.
-
potential of Nitrogen Gas N2 flushing to extend the shelf life of cold stored pasteurised milk
International Journal of Molecular Sciences, 2013Co-Authors: Patricia Munschalatossava, Abdul Ghafar, Tapani AlatossavaAbstract:For different reasons, the amount of food loss for developing and developed countries is approximately equivalent. Altogether, these losses represent approximately 1/3 of the global food production. Significant amounts of pasteurised milk are lost due to bad smell and unpleasant taste. Currently, even under the best cold chain conditions, psychrotolerant spore-forming bacteria, some of which also harbour virulent factors, limit the shelf life of pasteurised milk. N2 Gas-based flushing has recently been of interest for improving the quality of raw milk. Here, we evaluated the possibility of addressing bacterial growth in pasteurised milk during cold storage at 6 °C and 8 °C. Clearly, the treatments hindered bacterial growth, in a laboratory setting, when N2-treated milk were compared to the corresponding controls, which suggests that N2-flushing treatment constitutes a promising option to extend the shelf life of pasteurised milk.
-
potential of Nitrogen Gas N2 to control psychrotrophs and mesophiles in raw milk
Microbiological Research, 2010Co-Authors: Patricia Munschalatossava, Oguz Gursoy, Tapani AlatossavaAbstract:Summary Pure N 2 Gas was introduced in the headspace of test bottles containing raw milk that were then stored at either 6.0, 7.0, or 12.0 °C. Treatment with N 2 significantly reduced the growth of total bacteria, and the growth of bacterial subgroups such as psychrotrophs, enterobacteria, protease- and lipase-producing bacteria, and Listeria spp, and completely excluded Bacillus cereus growth on MYP plates. The inhibitory effect was maximal at 6.0 °C, and bacterial growth could be halted at this temperature for 11 days. At 12.0 °C, N 2 was able to inhibit growth during the first 48 h. No alarming or undesirable effects, such as the excessive growth of anaerobes or lactobacilli, were observed during the course of the study. The same treatments also halted the growth of one bacterial isolate in pure culture that expressed multiresistance to antibiotics. The continuous flushing of raw milk with pure N 2 Gas in a so-called open system that allows Gas exchanges with the environment positively impacted the microbiological quality of the raw milk at a temperature range of 6.0–12.0 °C. This procedure should therefore be considered as a possible complementary method to refrigeration in controlling bacterial growth and the spoilage potential of both psychrotrophs and mesophiles in raw milk.
-
exclusion of phospholipases pls producing bacteria in raw milk flushed with Nitrogen Gas N2
Microbiological Research, 2010Co-Authors: Patricia Munschalatossava, Oguz Gursoy, Tapani AlatossavaAbstract:Summary Prolonged cold storage of raw milks favors the growth of psychrotrophs, which produce heat-resistant exoenzymes of considerable spoilage potential; the bacterial proteases and lipases affect raw milk quality; among them phospholipases (PLs) may target the milk fat globule. More importantly, bacterial PLs are key virulence factors for numerous species. Two studies examined the use of Nitrogen (N 2 ) Gas and examined its effect on psychrotrophs, proteases and lipase producers when the milk was stored in closed vessels; however, the effect on PLs producers is unknown. Here we show that by considering an open system the PLs producers were sooner or later excluded in raw milk (whereas the PLs producers in the non-treated controls culminated at 10 8 CFU/ml), by effective Gas treatments that bring oxygen (O 2 ) levels in milk lower than 0.1 ppm. No increase of the PLs producers among the anaerobes was noticed during the course of the experiments. In the experiments performed at 6.0 °C, the delay after which the PLs producers were no longer detectable seemed independent of the initial level of PLs producers in raw milk (lower than 10 3 CFU/ml). We anticipate that flushing pure N 2 Gas in raw milk tanks, considered as open systems, along the cold chain of raw milk storage and transportation, may be an additional technique to control psychrotrophs, and may also constitute an interesting perspective for limiting their spoilage and pathogenic potential in food materials in general.
Jean A. Laissue - One of the best experts on this subject based on the ideXlab platform.
-
characterization of a tungsten Gas multislit collimator for microbeam radiation therapy at the european synchrotron radiation facility
Review of Scientific Instruments, 2005Co-Authors: Elke Brauerkrisch, E A Siegbahn, Jan Stepanek, D N Slatkin, M Jasmin, Hans Blattmann, J O Gebbers, Alberto Bravin, L. Zhang, Jean A. LaissueAbstract:Clinical microbeam radiation therapy (MRT) will require a multislit collimator with adjustable uniform slit widths to enable reliable Monte Carlo-based treatment planning. Such a collimator has been designed, fabricated of >99% tungsten [W] by Tecomet/Viasys (Woburn, Massachusetts, USA) and installed at the 6GeV electron-wiggler-generated hard x-ray ID17 beamline of the European Synchrotron Radiation Facility. Its pair of 125 parallel, 8mm deep, 0.100mm wide radiolucent slits, 0.400mm on center, are perfused with Nitrogen Gas [N2] to dissipate heat during irradiation. Major improvements in uniformity of microbeam widths and good peak/valley dose ratios combined with a very high dose rate in targeted tissues have been achieved.
-
Characterization of a tungsten/Gas multislit collimator for microbeam radiation therapy at the European Synchrotron Radiation Facility
Review of Scientific Instruments, 2005Co-Authors: Elke Bräuer-krisch, E A Siegbahn, Jan Stepanek, D N Slatkin, M Jasmin, Hans Blattmann, J O Gebbers, Alberto Bravin, L. Zhang, Jean A. LaissueAbstract:Clinical microbeam radiation therapy (MRT) will require a multislit collimator with adjustable uniform slit widths to enable reliable Monte Carlo-based treatment planning. Such a collimator has been designed, fabricated of >99% tungsten [W] by Tecomet/Viasys (Woburn, Massachusetts, USA) and installed at the 6GeV electron-wiggler-generated hard x-ray ID17 beamline of the European Synchrotron Radiation Facility. Its pair of 125 parallel, 8mm deep, 0.100mm wide radiolucent slits, 0.400mm on center, are perfused with Nitrogen Gas [N2] to dissipate heat during irradiation. Major improvements in uniformity of microbeam widths and good peak/valley dose ratios combined with a very high dose rate in targeted tissues have been achieved.
Christopher P. Colella - One of the best experts on this subject based on the ideXlab platform.
-
Optimization of an urea decomposition chamber using CFD and VR
Applied Thermal Engineering, 2014Co-Authors: Bin Wu, Guangwu Tang, Xingjian Chen, Chenn Q. Zhou, Christopher P. Colella, Tyamo OkosunAbstract:Abstract Selective Catalytic Reduction (SCR) is an important air pollution control process that consists of injecting ammonia (NH3) into the boiler flue Gas and passing the flue Gas through a catalyst bed where the NOx and NH3 react to form Nitrogen Gas (N2) and water vapor (H2O). At a coal-fired power station, a decomposition chamber uses combustion air and a natural Gas burner to provide the necessary temperature, air flow and pressure to convert the injected urea solution into ammonia Gas. Inspections of this decomposition chamber indicate debris formations occurring at the burner/roof prevent the chamber from achieving proper temperature for conversion and redirect the burner flame/flow, which can potentially shift the flow pattern in the chamber. In order to identify the cause of this debris formation, Computational Fluid Dynamics (CFD) and Virtual Reality (VR) have been employed to simulate and visualize the flow distribution and species concentration inside this decomposition chamber. By analyzing the simulation data, excessive ammonia recirculation have been identified as the cause of the debris formation at the top of the chamber. Parametric studies have also been conducted to optimize the existing chamber design by introducing multiple baffles to eliminate the excessive recirculation, thus minimizing debris formation.
-
Optimization of an Urea Decomposition Chamber Using CFD and VR
Volume 2: Heat Transfer Enhancement for Practical Applications; Heat and Mass Transfer in Fire and Combustion; Heat Transfer in Multiphase Systems; He, 2013Co-Authors: Xingjian Chen, Bin Wu, Guangwu Tang, Chenn Q. Zhou, Christopher P. ColellaAbstract:Selective Catalytic Reduction (SCR) is an important air pollution control process that consists of injecting ammonia (NH3) into the boiler flue Gas and passing the flue Gas through a catalyst bed where the NOx and NH3 react to form Nitrogen Gas (N2) and water vapor (H2O). [1] At a coal-fired power station, a decomposition chamber uses combustion air and a natural Gas burner to provide the necessary temperature, air flow and pressure to convert the injected urea solution into ammonia Gas. The inspections of this decomposition chamber indicate debris formations occurring at the burner/roof block the chamber from achieving proper temperature for conversion and redirect the burner flame/flow, which can potentially shift the flow pattern in the chamber. In order to identify the cause of this debris formation, Computational Fluid Dynamics (CFD) and Virtual reality fVR have been employed to simulate and visualize the flow distribution and species concentration inside this decomposition chamber. By analyzing the simulation data, excessive ammonia recirculation had been identified as the cause of the debris formation at the top of the chamber. Parametric studies have also been conducted to optimize the existing chamber design by introducing multiple turning vanes to eliminate the excessive recirculation, thus minimizing debris formation.Copyright © 2013 by ASME
Alberto Bravin - One of the best experts on this subject based on the ideXlab platform.
-
characterization of a tungsten Gas multislit collimator for microbeam radiation therapy at the european synchrotron radiation facility
Review of Scientific Instruments, 2005Co-Authors: Elke Brauerkrisch, E A Siegbahn, Jan Stepanek, D N Slatkin, M Jasmin, Hans Blattmann, J O Gebbers, Alberto Bravin, L. Zhang, Jean A. LaissueAbstract:Clinical microbeam radiation therapy (MRT) will require a multislit collimator with adjustable uniform slit widths to enable reliable Monte Carlo-based treatment planning. Such a collimator has been designed, fabricated of >99% tungsten [W] by Tecomet/Viasys (Woburn, Massachusetts, USA) and installed at the 6GeV electron-wiggler-generated hard x-ray ID17 beamline of the European Synchrotron Radiation Facility. Its pair of 125 parallel, 8mm deep, 0.100mm wide radiolucent slits, 0.400mm on center, are perfused with Nitrogen Gas [N2] to dissipate heat during irradiation. Major improvements in uniformity of microbeam widths and good peak/valley dose ratios combined with a very high dose rate in targeted tissues have been achieved.
-
Characterization of a tungsten/Gas multislit collimator for microbeam radiation therapy at the European Synchrotron Radiation Facility
Review of Scientific Instruments, 2005Co-Authors: Elke Bräuer-krisch, E A Siegbahn, Jan Stepanek, D N Slatkin, M Jasmin, Hans Blattmann, J O Gebbers, Alberto Bravin, L. Zhang, Jean A. LaissueAbstract:Clinical microbeam radiation therapy (MRT) will require a multislit collimator with adjustable uniform slit widths to enable reliable Monte Carlo-based treatment planning. Such a collimator has been designed, fabricated of >99% tungsten [W] by Tecomet/Viasys (Woburn, Massachusetts, USA) and installed at the 6GeV electron-wiggler-generated hard x-ray ID17 beamline of the European Synchrotron Radiation Facility. Its pair of 125 parallel, 8mm deep, 0.100mm wide radiolucent slits, 0.400mm on center, are perfused with Nitrogen Gas [N2] to dissipate heat during irradiation. Major improvements in uniformity of microbeam widths and good peak/valley dose ratios combined with a very high dose rate in targeted tissues have been achieved.