• Korean Journal of Food Science and Technology
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• v.31 no.5
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• pp.1247-1253
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• 1999

Yakju(rice wine) was sterilized with high-voltage pulses of short time on a batch pulsed electric field(PEF) system. The initial microbial counts of Yakju were 7.52 X $10^4\;CFU/mL$ for total aerobes, 2.20 X $10^4\;CFU/mL$ for lactic acid bacteria and 7.08 X $10^4\;CFU/mL$ for yeasts. The pH, acidity and electric conductivity of Yakju were 3.36, 0.462% and 1.24 mS/cm, respectively. Yakju was treated with 2-250 of pulses exponential-wave formed electric pulses under the field strength of 12.5-25 kV/cm. The critical strengths of the electrical field for the sterilization of Yakju were 7.5 kV/cm for total aerobes, 8.5 kV/cm for lactic acid bacteria and 6.5 kV/cm for yeasts. Logarithmic survival rates decreased linearly at low pulse number, but curvilinearly at high pulse number. The PEF sterilization kinetics of Yakju could be analysed by In s = In A-k In (n) and the sterilization rate constant increased with electric field strength and the size of target microorganisms. No changed in pH, acidity, and the growth of microorganisms were found in the PEF treated Yakju during the storage for 6 weeks at both $4^{\circ}C$ And $30^{\circ}C$.

• Korean Journal of Food Science and Technology
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• v.44 no.6
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• pp.704-710
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• 2012

This study was designed to investigate the effect of pulsed electric fields on the drying of ginseng and extraction of dried ginseng to reduce energy-consumption. Fresh ginseng was treated in a PEF system of 1 and 2 kV/cm electric field strength, 25 and 200 Hz of frequency, $30{\mu}s$ of pulse width and pulse number of 175. The samples were subsequently dried for 26 h at $55{\pm}1^{\circ}C$, and the characteristic of hot-water extraction on dried ginseng was investigated. The ginseng pretreated with an intensity of 2 kV/cm (200 Hz, n=175) resulted in a reduction of approximately 38% for drying time. The influence of PEF treatment on the water extraction of dried ginseng at $95{\pm}1^{\circ}C$ was also investigated. The application of an electric field intensity of 2 kV/cm (25 and 200 Hz, n=175) increased soluble solid content, significantly reducing sugar content and free sugar content of the extract compared to non-PEF-treated samples.

• Journal of Dairy Science and Biotechnology
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• v.32 no.1
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• pp.31-36
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• 2014

Thermal pasteurization has been effectively used for decades as a method to extend the shelf life of milk and to inactivate any pathogenic bacteria that it may contain; however, it can negatively affect the nutritional properties of milk. In recent years, the food industry has sought new, less aggressive technologies that affect food freshness and its nutritive and health benefits less significantly. Various means have been used to extend the shelf life of dairy foods, such as high-pressure processing, irradiation, ohmic heating, and pulsed electric field (PEF) technologies. Of these, PEF technologies are potential alternatives to traditional thermal milk pasteurization, owing to their advantages in minimizing sensory and nutritional damage. In this review, we have primarily focused on the feasibility of applying PEF technologies to the sterilization of dairy products and briefly discussed whether they should be adopted for use in the dairy beverage industry in the future.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.375-379
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• 1999

This study was designed to develop non-thermal pasteurized fresh apple juice by applying pulsed electric field (PEF) treatment. The effect of non-thermal PEF treatment on physicochemical and sensory properties of apple juice was examined by measuring changes in vitamin C contents, colors, flavors and sensory properties. Color of PEF and heat treated apple juices was not significantly different from each other. Vitamin C content of PEF treated apple juice was close to that of fresh apple juice, but was much higher than that of heat treated apple juice. Heat treated apple juice lost 70% of flavor components, whereas PEF-treated apple juice lost only 15%. Sensory scores of PEF treated apple juice were significantly higher than heat-treated one in flavor, taste and overall acceptability. In conclusion, PEF treated apple juice had superior physico-chemical and sensory properties to heat-treated one.

• Food Science and Preservation
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• v.19 no.5
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• pp.665-671
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• 2012

The effects of pretreatment by pulsed electric fields (PEFs) on the juice expression characteristics of the Malus pumila fruit were investigated. Fresh fruits were divided into quarters, were produced on a laboratory scale (100 g apples per lot) by pretreatment with electric fields at two different field intensities (1, 2 kV/cm; n=50, 100, 200, and 400 pulses), and were then pressed at room temperature. Relative to the control samples, the juice yield increased with increasing field intensities. The total phenolics and antioxidant activity were higher in the juice from the PEF-treated fruit than in the juice from the untreated fruit. There was no significant difference in soluble-solid and reducing sugar contents between the PEF-treated and untreated fruits. These results suggest that PEF pretreatment may be useful for increasing the juice yield, total phenolics, and antioxidant activity of the Malus pumila fruit.

• Journal of Animal Science and Technology
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• v.46 no.5
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• pp.871-878
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• 2004

Pulsed electric fields(PEF) technology is one of the latest nonthermal methods of food processing for obtaining safe and minimally processed foods. This technology can be effectively explored for obtaining safe food with minimum effect on nutritional, flavor, rheological and sensory qualities of food products. The process involves the application of high voltage(typically 20 ${\sim}$ 80 kv/cm) to foods placed between two electrodes. The mode of inactivation of microorganism; by PEP processing has been postulated in term; of electric breakdown and electroporation. The extent of destruction of microorganisms in PEF processing depends mainly on the electric field strength of the pulses and treatment time. For each cell types, a specific critical electric field strength and specific critical treatment time are required depending on the cell characteristics and the type and strength of the medium where they have been present. The effect also depends on the types of microorganisms and their phase of growth. A careful combination of processing parameters has to be selected for effective processing. The potential applications of PEF technology are numerous ranging from biotechnology to food preservation. With respect to food processing, it has already been established that, the technology is non-thermal in nature, economical and energy efficient, besides providing minimally processed foods. This article gives a brief overview of this technology for food processing applications.

• Korean Journal of Food Science and Technology
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• v.45 no.5
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• pp.590-597
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• 2013

High voltage pulsed electric fields (PEF) treatment is a promising non-thermal processing technology that can replace or partially substitute for thermal processes. The aim of this research was to investigate the microbial inactivation mechanisms by PEF treatment in terms of physiological changes to Saccharomyces cerevisiae. PEF was applied at the electric field strength of 50 kV/cm, treatment time of 56 ${\mu}s$ and temperature of $40^{\circ}C$. The microbial cells treated with PEF showed loss of salt tolerance on the cell membrane and collapse of the relative pH gradient on in-out of cells. Cell death or injury resulted from the breakdown of homeostasis, decreased $H^+$-ATPase activity, and loss of glycolysis activity.

• Korean Journal of Food Science and Technology
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• v.31 no.2
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• pp.410-415
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• 1999

Yakju was sterilized with high-voltage pulses of short time of a continuous pulsed electric field (PEF) system. The initial microbial counts of Yakju were $2.2{\times}10^{5}$ CFU/mL for total aerobes. The pH, acidity and electric conductivity of Yakju were 3.82, 0.37% and 1.24 mS/cm, respectively. Yakju was treated with exponential-wave formed electric pulses of 100 Hz for $0{\sim}4000{\mu}s$ under the field strength of $20{\sim}35\;kV/cm$. The lethal effect of electric fields on microorganisms was resulted from the breakdown of the cell membrane induced by the transmembrane electric potential. The critical values of the external field for the sterilization were 16.0 kV/cm for total aerobes. Logarithmic survival rates decreased linearly at low electric field strength, but curvilinearly at high electric field strength with treatment time. The sterilization of Yakju was more largely affected by the electric field strength than by the treatment time. Any changes in pH, acidity, and the growth of microorganisms were not found in the PEF treated Yakju during the storage at both $4^{\circ}C\;and\;30^{\circ}C$.

• Food Science and Preservation
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• v.14 no.2
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• pp.165-169
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• 2007

High voltage pulsed electric fields (PEF) is a promising technology for the nonthermal extraction of effective components from biological materials. Plant cells were ruptured with PEF at ambient or refrigerated temperature for a short treatment time of second or microsecond. Treatments of coarsely ground purple sweet potato (PSP) with PEF(30 kV/cm, 500 Hz) resulted in maximum extraction yield of 65% as compared with 45-50% for control. An increase in electric field strength (from 10kV/cm to 35kV/cm) and frequency (from 100Hz to 500Hz) resulted in increased amount of extracted pigments, but treatment time is not affected on pigment extraction. Starch granules were not detected and large intracellular spaces were visible between the cells on light and scanning election microscopy of PEF treated PSP. This result suggests that PEF have potential to use on extraction of pigments from plant cells.

• Journal of Ginseng Research
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• v.41 no.2
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• pp.169-179
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• 2017

Background: Ginsenosides are the main pharmacological components of Panax ginseng root, which are thought to be primarily responsible for the suppressing effect on oxidative stress. Methods: 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and oxygen radical absorption capacity were applied to evaluate the antioxidant activities of the ginsenosides. Human embryonic kidney 293 (HEK-293) cells were incubated with ginsenosides extracted by pulsed electric field (PEF) and solvent cold soak extraction (SCSE) for 24 h and then the injury was induced by $40{\mu}M$ $H_2O_2$. The cell viability and surface morphology of HEK-293 cells were studied using MTS assay and scanning electron microscopy, respectively. Dichloro-dihydro-fluorescein diacetate fluorescent probe assay was used to measure the level of intracellular reactive oxygen species. The intracellular antioxidant activities of ginsenosides were evaluated by cellular antioxidant activity assay in HepG2 cells. Results: The PEF extracts displayed the higher 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and stronger oxygen radical absorption capacity (with an oxygen radical absorption capacity value of $14.48{\pm}4.04{\mu}M\;TE\;per\;{\mu}g/mL$). The HEK-293 cell model also suggested that the protective effect of PEF extracts was dose-dependently greater than SCSE extracts. Dichloro-dihydro-fluorescein diacetate assay further proved that PEF extracts are more active (8% higher than SCSE extracts) in reducing intracellular reactive oxygen species accumulation. In addition, scanning electron microscopy images showed that the HEK-293 cells, which were treated with PEF extracts, maintained more intact surface morphology. Cellular antioxidant activity values indicated that ginsenosides extracted by PEF had stronger cellular antioxidant activity than SCSE ginsenosides extracts. Conclusion: The present study demonstrated the antioxidative effect of ginsenosides extracted by PEF in vitro. Furthermore, rather than SCSE, PEF may be more useful as an alternative extraction technique for the extraction of ginsenosides with enhanced antioxidant activity.