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Dong-hyun Kang - One of the best experts on this subject based on the ideXlab platform.
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Investigation of a new UVC LEDs array continuous type water disinfection system for inactivating Escherichia coli O157:H7 according to flow Rate and electrical energy efficiency analysis
Food Control, 2021Co-Authors: Kyun Kim, Dong-hyun KangAbstract:Abstract UVC LEDs are gaining popularity for its advantages which compensate for the limitations of low-pressure mercury UV lamps. In order to investigate the efficacy of UVC LEDs-based continuous water disinfection system, various numbers of UVC LEDs chips were introduced to inactivate Escherichia coli O157:H7 in water. Also, the effect of an aluminum reflector in the irradiation system was investigated in order to enhance bacterial Inactivation. Without the reflector, the pathogen Inactivation profile showed a sigmoidal curve, while linear fitting was shown for the treatment with the reflector, and there was a 1.5 times greater bactericidal effect when the reflector was installed. Based on the Inactivation Rate Constant, no significant differences were revealed among the UVC LEDs chip arrays. Electrical energy efficiency necessary for 3- and 5-log reductions were calculated and the 18 UVC LEDs chip array consumed 30% less energy compared to the 33 UVC LEDs array. In this study, kinetic profiles of E. coli O157:H7 in a continuous water disinfection system using UVC LEDs irradiation with or without a reflector under various operational currents were obtained. Electrical energy consumption was considered in order to optimize the efficacy of this disinfection system. These results can be used as practical database to develop a water disinfection system using UVC LEDs and attributed to water and food safety.
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Inactivation modeling of human enteric virus surrogates, MS2, Qβ, and ΦX174, in water using UVC-LEDs, a novel disinfecting system.
Food Research International, 2016Co-Authors: Dong-hyun KangAbstract:Abstract In order to assure the microbial safety of drinking water, UVC-LED treatment has emerged as a possible technology to replace the use of conventional low pressure (LP) mercury vapor UV lamps. In this investigation, Inactivation of Human Enteric Virus (HuEV) surrogates with UVC-LEDs was investigated in a water disinfection system, and kinetic model equations were applied to depict the surviving infectivities of the viruses. MS2, Qβ, and ΦX 174 bacteriophages were inoculated into sterile distilled water (DW) and irradiated with UVC-LED printed circuit boards (PCBs) (266 nm and 279 nm) or conventional LP lamps. Infectivities of bacteriophages were effectively reduced by up to 7-log after 9 mJ/cm2 treatment for MS2 and Qβ, and 1 mJ/cm2 for ΦX 174. UVC-LEDs showed a superior viral Inactivation effect compared to conventional LP lamps at the same dose (1 mJ/cm2). Non-log linear plot patterns were observed, so that Weibull, Biphasic, Log linear-tail, and Weibull-tail model equations were used to fit the virus survival curves. For MS2 and Qβ, Weibull and Biphasic models fit well with R2 values approximately equal to 0.97–0.99, and the Weibull-tail equation accuRately described survival of ΦX 174. The level of UV-susceptibility among coliphages measured by the Inactivation Rate Constant, k, was statistically different (ΦX 174 (ssDNA) > MS2, Qβ (ssRNA)), and indicated that sensitivity to UV was attributed to viral genetic material.
Kumiko Oguma - One of the best experts on this subject based on the ideXlab platform.
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Inactivation of feline calicivirus using ultraviolet light emitting diodes
Fems Microbiology Letters, 2018Co-Authors: Kumiko OgumaAbstract:Ultraviolet light-emitting diodes (UV-LEDs) with peak emission wavelengths of 265, 280 and 300 nm were applied for the Inactivation of feline calicivirus (FCV) in water, and the results were compared to those derived with a common viral surrogate coliphage MS2. The fluence response profiles indicated that the log10-based Inactivation Rate Constant of FCV was 0.113, 0.101 and 0.007 cm2 mJ-1 for the 265, 280 and 300 nm UV-LEDs, respectively, while that of MS2 was 0.034, 0.033 and 0.003 cm2 mJ-1 for the 265, 280 and 300 nm UV-LEDs, respectively. Namely, FCV was about two to three times more sensitive than MS2 to germicidal UV emissions adopted in this study, and the 265 nm and 280 nm UV-LEDs were particularly effective to inactivate FCV. Results of this study are to be a part of database on fluence response profiles of various microorganisms, which would foster the development of disinfection apparatuses equipped with UV-LEDs.
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Inactivation kinetics and efficiencies of UV-LEDs against Pseudomonas aeruginosa, Legionella pneumophila, and surrogate microorganisms
Water Research, 2018Co-Authors: Surapong Rattanakul, Kumiko OgumaAbstract:To demonstRate the effectiveness of UV light-emitting diodes (UV-LEDs) to disinfect water, UV-LEDs at peak emission wavelengths of 265, 280, and 300 nm were adopted to inactivate pathogenic species, including Pseudomonas aeruginosa and Legionella pneumophila, and surrogate species, including Escherichia coli, Bacillus subtilis spores, and bacteriophage Qβ in water, compared to conventional low-pressure UV lamp emitting at 254 nm. The Inactivation profiles of each species showed either a linear or sigmoidal survival curve, which both fit well with the Geeraerd's model. Based on the Inactivation Rate Constant, the 265-nm UV-LED showed most effective fluence, except for with E. coli which showed similar Inactivation Rates at 265 and 254 nm. Electrical energy consumption required for 3-log10 Inactivation (EE,3) was lowest for the 280-nm UV-LED for all microbial species tested. Taken together, the findings of this study determined the Inactivation profiles and kinetics of both pathogenic bacteria and surrogate species under UV-LED exposure at different wavelengths. We also demonstRated that not only Inactivation Rate Constants, but also energy efficiency should be considered when selecting an emission wavelength for UV-LEDs.
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application of uv light emitting diodes to batch and flow through water disinfection systems
Desalination, 2013Co-Authors: Kumiko Oguma, Ryo Kita, H Sakai, Michio Murakami, Satoshi TakizawaAbstract:Abstract UV light emitting diodes (UV-LEDs) with peak emissions at 265, 280 and 310 nm were applied to batch and flow-through water disinfection systems. Inactivation efficiency of Escherichia coli was compared between reactors and among emissions based on the exposure time and fluence. Combined emissions at 265/280, 265/310, 280/310 and 265/280/310 nm were also tested in the flow-through reactor. The time-based Inactivation efficiency was highest with the 280 nm UV-LED while the fluence-based efficiency was highest with the 265 nm UV-LED. In the batch reactor, the UV-LEDs at 265 and 280 nm achieved over 4 log Inactivation of E. coli at fluences of 10.8 and 13.8 mJ/cm 2 , respectively, while the UV-LED at 310 nm required 56.9 mJ/cm 2 for 0.6 log Inactivation. The flow-through reactor showed tailing in the fluence-response curves and resulted in lower Inactivation efficiency than the batch reactor, with lower fluence-based Inactivation Rate Constant of 29% for 265 nm and 32% for 280 nm. Combined emissions were less efficient than the component emissions applied sepaRately, and reduced output power for each UV-LED was observed for combined cases. This study provides key implications for the future application of UV-LEDs to water disinfection systems.
Marc Hendrickx - One of the best experts on this subject based on the ideXlab platform.
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investigating the potential of bacillus subtilis α amylase as a pressure temperature time indicator for high hydrostatic pressure pasteurization processes
Biotechnology Progress, 2009Co-Authors: Tara Grauwet, Marc Hendrickx, Iesel Van Der Plancken, Liesbeth Vervoort, Ann Van LoeyAbstract:The potential of Bacillus subtilis α-amylase (BSA) as a pressure-temperature-time indicator (pTTI) for high pressure pasteurization processing (400–600 MPa; Ti 10–40°C; 1–15 min) was investigated. A stepwise approach was followed for the development of an enzyme-based, extrinsic, isolated pTTI. First, based on literature data on the pressure stability, BSA was selected as a candidate indicator. Next to the accuracy and ease of the measurement of the indicator's response (residual activity) to the pressure treatment, the storage and handling stability of BSA at atmospheric pressure was verified. Second, the stability of BSA at a Constant temperature (T) and time in function of pressure (p) was investigated. Solvent engineering was used to shift the Inactivation window of BSA in the processing range of interest. Third, the enzyme (1 g/L BSA—MES 0.05 M pH 5.0) was kinetically calibRated under isobaric-isothermal conditions. Time dependent changes in activity could be modeled best by a first-order model. Except for low pressures and high temperatures, a synergistic effect between pressure and temperature could be observed. Based on the model selected to describe the combined p,T-dependency of the Inactivation Rate Constant, an elliptically shaped isoRate contour plot could be constructed, illustrating the processing range where BSA can be used to demonstRate temperature gradients. Fourth, the validity of the kinetic model was tested successfully under dynamic conditions similar to those used in food industry. Finally, the indicator was found suitable to demonstRate nonuniformity in two-sectional planes of a vertical, single vessel system. © 2009 American Institute of Chemical Engineers. Biotechnol. Prog., 2009
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Inactivation kinetics of polygalacturonase in tomato juice
Innovative Food Science and Emerging Technologies, 2003Co-Authors: D Fachin, Ann Van Loey, Binh Ly Nguyen, I Verlent, Marc HendrickxAbstract:a ¸ ´´ ˜ ´ Abstract The Inactivation kinetics of polygalacturonase (PG) in tomato juice was studied during thermal and high-pressureythermal processing. In the temperature range of 55-70 8C the thermal Inactivation of polygalacturonase in tomato juice followed a fractional conversion model, with a thermostable fraction of approximately 14%. Under conditions of combined high-pressurey thermal processing, 200-550 MPay5-50 8C, PG Inactivation presented first order kinetics. A mathematical model to describe the Inactivation Rate Constant as a function of pressure and temperature was formulated. Industrial relevance: Polygalacturonase is responsible for the decrease of viscosity in tomato-based products. However, little research on thermal and high pressure ythermal Inactivation kinetics of tomato Polygalacturonase has been reported. This research clearly shows that it is possible to selectively inactivate PG by high pressureythermal processing without applying high temperatures. This leads to tomato-based products with improved functional properties while other quality attributes (color, flavor, nutritional value ) are maintained. 2002 Elsevier Science Ltd. All rights reserved.
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Inactivation of orange pectinesterase by combined high pressure and temperature treatments a kinetic study
Journal of Agricultural and Food Chemistry, 2000Co-Authors: Ilse Van Den Broeck, L Ludikhuyze, And Ann Van Loey, Marc HendrickxAbstract:Pressure and/or temperature Inactivation of orange pectinesterase (PE) was investigated. Thermal Inactivation showed a biphasic behavior, indicating the presence of labile and stable fractions of the enzyme. In a first part, the Inactivation of the labile fraction was studied in detail. The combined pressure−temperature Inactivation of the labile fraction was studied in the pressure range 0.1−900 MPa combined with temperatures from 15 to 65 °C. Inactivation in the pressure−temperature domain specified could be accuRately described by a first-order fractional conversion model, estimating the Inactivation Rate Constant of the labile fraction and the remaining activity of the stable fraction. Pressure and temperature dependence of the Inactivation Rate Constants of the labile fraction was quantified using the Eyring and Arrhenius relations, respectively. By replacing in the latter equation the pressure-dependent parameters (Ea, krefT) by mathematical expressions, a global model was formulated. This mathemati...
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kinetics of combined pressure temperature Inactivation of avocado polyphenoloxidase
Biotechnology and Bioengineering, 1998Co-Authors: C Weemaes, L Ludikhuyze, Ilse Van Den Broeck, Marc HendrickxAbstract:Irreversible combined pressure-temperature Inactivation of the food quality related enzyme polyphenoloxidase was investigated. Inactivation Rate Constants (k) were obtained for about one hundred combinations of Constant pressure (0.1–900 MPa) and temperature (25–77.5°C). According to the Eyring and Arrhenius equation, activation volumes and activation energies, respectively, representing pressure and temperature dependence of the Inactivation Rate Constant, were calculated for all temperatures and pressures studied. In this way, temperature and pressure dependence of activation volume and activation energy, respectively, could be considered. Moreover, for the first time, a mathematical model describing the Inactivation Rate Constant of a food quality-related enzyme as a function of pressure and temperature is formulated. Such pressure-temperature Inactivation models for food quality-related aspects (e.g., the spoilage enzyme polyphenoloxidase) form the engineering basis for design, evaluation, and optimization of new preservation processes based on the combined effect of temperature and pressure. Furthermore, the geneRated methodology can be used to develop analogous kinetic models for microbiological aspects, which are needed from a safety and legislative point of view, and other quality aspects, e.g., nutritional factors, with a view of optimal quality and consumer acceptance. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 292–300, 1998.
Petros Taoukis - One of the best experts on this subject based on the ideXlab platform.
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high hydrostatic pressure Inactivation kinetics of the plant proteases ficin and papain
Journal of Food Engineering, 2009Co-Authors: George I. Katsaros, Petros Katapodis, Petros TaoukisAbstract:Abstract Papain and ficin are general non-specific plant thiol proteases applied in food processing. Inactivation kinetics of papain and ficin were studied for thermal (50–80 °C, ambient pressure) and high pressure/temperature (500–900 MPa at 50–80 °C) process conditions. The effect of temperature at each pressure and the effect of pressure at each temperature were expressed by the values of activation energy, E a , and activation volume, V a . The two enzymes showed the same Inactivation under thermal process. At high pressures, at each process temperature, increase of pressure increases the Inactivation Rate. Up to 60 °C for ficin and 70 °C for papain, Inactivation Rates at high pressures are higher than the corresponding thermal Rates at ambient pressure. At higher temperatures up to certain pressures an antagonistic effect was observed. At 80 °C thermal Inactivation Rates at all high pressures are lower than the ones at ambient pressure. E a increased for papain (from 50 to 88 kJ/mol) and decreased for ficin (from 139 to 43 kJ/mol) as process pressure increased, a different effect of pressure on temperature sensitivity. V a depended on process temperature showing increasing effect of pressure at higher temperatures for papain and decreasing for ficin. The enzymes Inactivation Rate Constant was modeled as a function of both temperature and pressure conditions by a multi-parameter equation. Overall, papain and ficin showed a high thermal and pressure stability requiring intense process conditions for adequate Inactivation.
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Inactivation kinetics of pectin methylesterase of greek navel orange juice as a function of high hydrostatic pressure and temperature process conditions
Journal of Food Engineering, 2004Co-Authors: A C Polydera, E Galanou, Nikolaos G Stoforos, Petros TaoukisAbstract:Abstract The Inactivation kinetics of endogenous pectin methylesterase (PME) in freshly squeezed orange juice under high hydrostatic pressure (100–800 MPa) combined with modeRate temperature (30–60 °C) was investigated. Atmospheric pressure conditions in a temperature range of 50–80 °C were also tested. PME Inactivation followed first order kinetics with a residual PME activity (5–20%) at all pressure–temperature combinations used. The values of activation energy and activation volume were estimated as 109 kJ mol −1 and −19.76 ml mol −1 at a reference pressure of 600 MPa and reference temperature of 50 °C respectively. Pressure and temperature were found to act synergistically, except in the high temperature–low pressure region where an antagonistic effect was found. The PME Inactivation Rate Constant was expressed as a function of the temperature and pressure process conditions used. This function incorpoRates the observed exponential dependence of activation energy on the pressure conditions, as well as the linear dependence of activation volume on process temperature.
Tristan S Maurer - One of the best experts on this subject based on the ideXlab platform.
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impact of mechanism based enzyme Inactivation on inhibitor potency implications for rational drug discovery
Journal of Pharmaceutical Sciences, 2000Co-Authors: Tristan S Maurer, Mohammad A Tabrizifard, Holeung FungAbstract:Mechanism-based enzyme inactivators (MBEIs) have unique kinetic actions that make predictions of potency, selectivity, and potential for metabolic drug interactions more complex than for competitive antagonists. We have derived a mathematical relationship that links the influence of substRate concentration and binding Constant ([S] and K(m), respectively), inhibitor concentration and binding Constant ([I] and K(I), respectively), and Inactivation Rate Constant (k(inact)) to enzyme activity (v) and maximal activity (V(max)) at any time (t). The kinetic behavior of this relationship was validated in murine-macrophage cell cultures using MBEIs of nitric oxide synthase (NOS). This initial equation was also used in the derivation of a new relationship that directly links the kinetic parameters of mechanism-based Inactivation to inhibitory potency at a particular time (IC((t))(50)). Using this direct relationship, we observed that the predicted rank inhibitory potency of a series of MBEIs was improved over that predicted by the K(I) parameter alone. These relationships offer a fundamental understanding of the kinetics of MBEI action and may be useful in the evaluation of these compounds during the discovery process.
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impact of mechanism based enzyme Inactivation on inhibitor potency implications for rational drug discovery
Journal of Pharmaceutical Sciences, 2000Co-Authors: Tristan S Maurer, Mohammad A Tabrizifard, Holeung FungAbstract:Abstract Mechanism‐based enzyme inactivators (MBEIs) have unique kinetic actions that make predictions of potency, selectivity, and potential for metabolic drug interactions more complex than for competitive antagonists. We have derived a mathematical relationship that links the influence of substRate concentration and binding Constant ([ S ] and K m , respectively), inhibitor concentration and binding Constant ([ I ] and K I , respectively), and Inactivation Rate Constant ( k inact ) to enzyme activity ( v ) and maximal activity ( V max ) at any time ( t ). The kinetic behavior of this relationship was validated in murine‐macrophage cell cultures using MBEIs of nitric oxide synthase (NOS). This initial equation was also used in the derivation of a new relationship that directly links the kinetic parameters of mechanism‐based Inactivation to inhibitory potency at a particular time ( I C 50 ( t ) ). Using this direct relationship, we observed that the predicted rank inhibitory potency of a series of MBEIs was improved over that predicted by the K I parameter alone. These relationships offer a fundamental understanding of the kinetics of MBEI action and may be useful in the evaluation of these compounds during the discovery process. © 2000 Wiley‐Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 89: 1404–1414, 2000
