scholarly journals Inactivation Kinetics and Membrane Potential of Pathogens in Soybean Curd Subjected to Pulsed Ohmic Heating Depending on Applied Voltage and Duty Ratio

2020 ◽  
Vol 86 (14) ◽  
Author(s):  
Eun-Rae Cho ◽  
Sang-Soon Kim ◽  
Dong-Hyun Kang
Keyword(s):  
Membrane Potential ◽  
Electric Field ◽  
Applied Voltage ◽  
Ohmic Heating ◽  
High Water ◽  
Microbial Inactivation ◽  
Duty Ratio ◽  
Inactivation Kinetics ◽  
Content Type ◽  
Soybean Curd

ABSTRACT The aim of this research was to investigate the efficacy of the duty ratio and applied voltage in the inactivation of pathogens in soybean curd by pulsed ohmic heating (POH). The heating rate of soybean curd increased rapidly as the applied voltage increased, although the duty ratio did not affect the temperature profile. We supported this result by verifying that electrical conductivity increased with the applied voltage. Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium, and Listeria monocytogenes in soybean curd were significantly (P < 0.05) inactivated by more than 1 log unit at 80 Vrms (root mean square voltage). To elucidate the mechanism underlying these results, the membrane potential of the pathogens was examined using DiBAC4(3) [bis-(1,3-dibutylbarbituric acid)trimethine oxonol] on the basis of a previous study showing that the electric field generated by ohmic heating affected the membrane potential of cells. The values of DiBAC4(3) accumulation increased under increasing applied voltage, and they were significantly (P < 0.05) higher at 80 Vrms, while the duty ratio had no effect. In addition, morphological analysis via transmission electron microscopy showed that electroporation and expulsion of intracellular materials were predominant at 80 Vrms. Moreover, electrode corrosion was overcome by the POH technique, and the textural and color properties of soybean curd were preserved. These results substantiate the idea that the applied voltage has a profound effect on the microbial inactivation of POH as a consequence of not only the thermal effect, but also the nonthermal effect, of the electric field, whereas the duty ratio does not have such an effect. IMPORTANCE High-water-activity food products, such as soybean curd, are vulnerable to microbial contamination, which causes fatal foodborne diseases and food spoilage. Inactivating microorganisms inside food is difficult because the transfer of thermal energy is slower inside than it is outside the food. POH is an adequate sterilization technique because of its rapid and uniform heating without causing electrode corrosion. To elucidate the electrical factors associated with POH performance in the inactivation of pathogens, the effects of the applied voltage and duty ratio on POH were investigated. In this study, we verified that a high applied voltage (80 Vrms) at a duty ratio of 0.1 caused thermal and nonthermal effects on pathogens that led to an approximately 4-log-unit reduction in a significantly short time. Therefore, the results of this research corroborate database predictions of the inactivation efficiency of POH based on pathogen control strategy modeling.

Dielectrophoresis velocities response on tapered electrode profile: simulation and experimental

2019 ◽  
Vol 36 (2) ◽  
pp. 45-53
Author(s):  
Muhammad Izzuddin Abd Samad ◽  
Muhamad Ramdzan Buyong ◽  
Shyong Siow Kim ◽  
Burhanuddin Yeop Majlis
Keyword(s):  
Electric Field ◽  
Field Intensity ◽  
Particle Velocity ◽  
Applied Voltage ◽  
Electric Field Intensity ◽  
Particle Trajectory ◽  
Numerical Study ◽  
Time Interval ◽  
Content Type ◽  
Field Density

Purpose The purpose of this paper is to use a particle velocity measurement technique on a tapered microelectrode device via changes of an applied voltage, which is an enhancement of the electric field density in influencing the dipole moment particles. Polystyrene microbeads (PM) have used to determine the responses of the dielectrophoresis (DEP) voltage based on the particle velocity technique. Design/methodology/approach Analytical modelling was used to simulate the particles’ polarization and their velocity based on the Clausius–Mossotti Factor (CMF) equation. The electric field intensity and DEP forces were simulated through the COMSOL numerical study of the variation of applied voltages such as 5 V p-p, 7 V p-p and 10 V p-p. Experimentally, the particle velocity on a tapered DEP response was quantified via the particle travelling distance over a time interval through a high-speed camera adapted to a high-precision non-contact depth measuring microscope. Findings The result of the particle velocity was found to increase, and the applied voltage has enhanced the particle trajectory on the tapered microelectrode, which confirmed its dependency on the electric field intensity at the top and bottom edges of the electrode. A higher magnitude of particle levitation was recorded with the highest particle velocity of 11.19 ± 4.43 µm/s at 1 MHz on 10 V p-p, compared to the lowest particle velocity with 0.62 ± 0.11 µm/s at 10 kHz on 7 V p-p. Practical implications This research can be applied for high throughout sensitivity and selectivity of particle manipulation in isolating and concentrating biological fluid for biomedical implications. Originality/value The comprehensive manipulation method based on the changes of the electrical potential of the tapered electrode was able to quantify the magnitude of the particle trajectory in accordance with the strong electric field density.

scholarly journals Effect of Electropermeabilization by Ohmic Heating for Inactivation of Escherichia coli O157:H7, Salmonella enterica Serovar Typhimurium, and Listeria monocytogenes in Buffered Peptone Water and Apple Juice

2013 ◽  
Vol 79 (23) ◽  
pp. 7122-7129 ◽  
Author(s):  
Il-Kyu Park ◽  
Dong-Hyun Kang
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Electric Field ◽  
Salmonella Enterica ◽  
Apple Juice ◽  
Ohmic Heating ◽  
Conventional Heating ◽  
Content Type ◽  
Serovar Typhimurium ◽  
Peptone Water

ABSTRACTThe effect of electric field-induced ohmic heating for inactivation ofEscherichia coliO157:H7,Salmonella entericaserovar Typhimurium, andListeria monocytogenesin buffered peptone water (BPW) (pH 7.2) and apple juice (pH 3.5; 11.8 °Brix) was investigated in this study. BPW and apple juice were treated at different temperatures (55°C, 58°C, and 60°C) and for different times (0, 10, 20, 25, and 30 s) by ohmic heating compared with conventional heating. The electric field strength was fixed at 30 V/cm and 60 V/cm for BPW and apple juice, respectively. Bacterial reduction resulting from ohmic heating was significantly different (P< 0.05) from that resulting from conventional heating at 58°C and 60°C in BPW and at 55°C, 58°C, and 60°C in apple juice for intervals of 0, 10, 20, 25, and 30 s. These results show that electric field-induced ohmic heating led to additional bacterial inactivation at sublethal temperatures. Transmission electron microscopy (TEM) observations and the propidium iodide (PI) uptake test were conducted after treatment at 60°C for 0, 10, 20, 25 and 30 s in BPW to observe the effects on cell permeability due to electroporation-caused cell damage. PI values when ohmic and conventional heating were compared were significantly different (P< 0.05), and these differences increased with increasing levels of inactivation of three food-borne pathogens. These results demonstrate that ohmic heating can more effectively reduce bacterial populations at reduced temperatures and shorter time intervals, especially in acidic fruit juices such as apple juice. Therefore, loss of quality can be minimized in a pasteurization process incorporating ohmic heating.

Effects of Ohmic Heating, Including Electric Field Intensity and Frequency, on Thermal Inactivation of Bacillus subtilis Spores

2016 ◽  
Vol 80 (1) ◽  
pp. 164-168 ◽  
Author(s):  
SUGURU MURASHITA ◽  
SHUSO KAWAMURA ◽  
SHIGENOBU KOSEKI
Keyword(s):  
Bacillus Subtilis ◽  
Electric Field ◽  
Field Intensity ◽  
Survival Data ◽  
Electric Field Intensity ◽  
Thermal Inactivation ◽  
Ohmic Heating ◽  
Weibull Model ◽  
Microbial Inactivation ◽  
Inactivation Effect

ABSTRACT Methods for microbial inactivation are important in the food industry; however, conventional external heating (CH) reduces food quality. Accordingly, the nonthermal effects of ohmic heating (OH) on Bacillus subtilis spores in a sodium chloride aqueous solution at 101°C (i.e., the boiling point), as well as the effects of electric field intensity and frequency during OH, were investigated. Survival kinetics were compared between OH and external CH. The inactivation effect on B. subtilis was greater for all electric field conditions (5, 10, and 20 V/cm) than for CH. In particular, 20 V/cm showed a significantly higher inactivation effect (P &lt; 0.05) on B. subtilis than those of CH at 8, 10, 12, 14, and 16 min. The survival data were fitted to various primary kinetic models. In the Weibull model and the log-linear model, there were significant differences (P &lt; 0.05) in the rate parameters δ and kmax between OH at 20 V/cm and CH. However, there were no significant differences (P &gt; 0.05) in survival kinetics between 20, 40, and 60 kHz; B. subtilis spores were inactivated more efficiently as the frequency increased. B. subtilis spores were almost completely inactivated at 14 to 16 min for the 60-kHz treatment, but spores were still alive at 20 and 40 kHz for the same treatment times. These results demonstrated that OH inactivates B. subtilis spores more effectively than CH. OH conditions with high electric field intensities and high frequencies resulted in efficient B. subtilis spore inactivation.

scholarly journals Improving the microbial inactivation uniformity of pulsed electric field ohmic heating treatments of solid products

LWT ◽  
2021 ◽  
pp. 112709
Author(s):  
L. Astráin-Redín ◽  
J. Moya ◽  
M. Alejandre ◽  
E. Beitia ◽  
J. Raso ◽  
...  
Keyword(s):  
Electric Field ◽  
Ohmic Heating ◽  
Pulsed Electric Field ◽  
Microbial Inactivation

scholarly journals Ohmic Heating in the Food Industry: Developments in Concepts and Applications during 2013–2020

2021 ◽  
Vol 11 (6) ◽  
pp. 2507
Author(s):  
Zina T. Alkanan ◽  
Ammar B. Altemimi ◽  
Asaad R. S. Al-Hilphy ◽  
Dennis G. Watson ◽  
Anubhav Pratap-Singh
Keyword(s):  
Energy Consumption ◽  
Ohmic Heating ◽  
Bioactive Compound ◽  
Heating Time ◽  
Microbial Inactivation ◽  
Conventional Heating ◽  
Food Ingredients ◽  
Physico Chemical ◽  
Key Characteristics ◽  
Comparable Performance

Various technologies have been evaluated as alternatives to conventional heating for pasteurization and sterilization of foods. Ohmic heating of food products, achieved by passage of an alternating current through food, has emerged as a potential technology with comparable performance and several advantages. Ohmic heating works faster and consumes less energy compared to conventional heating. Key characteristics of ohmic heating are homogeneity of heating, shorter heating time, low energy consumption, and improved product quality and food safety. Energy consumption of ohmic heating was measured as 4.6–5.3 times lower than traditional heating. Many food processes, including pasteurization, roasting, boiling, cooking, drying, sterilization, peeling, microbiological inhibition, and recovery of polyphenol and antioxidants have employed ohmic heating. Herein, we review the theoretical basis for ohmic treatment of food and the interaction of ohmic technology with food ingredients. Recent work in the last seven years on the effect of ohmic heating on food sensory properties, bioactive compound levels, microbial inactivation, and physico-chemical changes are summarized as a convenient reference for researchers and food scientists and engineers.

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