Pulsed Electric Field Parameters Research Articles

Potential of Pulsed Electric Fields for the preparation of Spanish dry-cured sausages

The aim of this investigation was to lay the groundwork of the potential application of Pulsed Electric Fields (PEF) technology for accelerating the drying process of meat and meat products, and specifically in this work of Spanish dry-cured sausages “longaniza”. PEF treatments were applied to pork loin samples, and the influence of different PEF parameters on the process were evaluated. An optimal PEF treatment of 1 kV/cm, 200 μs of pulse width and 28 kJ/kg was determined as the most suitable to electroporate meat cells and to improve water transfer by achieving a water content reduction of 60.4% in treated-meat samples dried at 4 °C. The influence of PEF on meat drying rate was also studied on minced pork and the results showed that with a particle size of 4.0 mm higher drying rates were achieved. To validate the results, Spanish cured sausages were prepared from treated and untreated minced pork and stuffed into gauzes and natural pork casings at pilot plant scale. After the curing process, the application of PEF to sausages stuffed into gauze reduced the drying time from 17 to 9–10 days, a reduction of 41–47%, confirming the effects described at lab scale and the potential of PEF for accelerating the sausage-drying process.

Electrophoretically Deposited Graphene-Based Coatings for Spacecraft Charging Mitigation

Spacecraft charging has been recognized as an important consideration for spacecraft design, and occurs due to interaction between hazardous space plasmas and spacecraft surface. Spacecraft can experience charging throughout operation due to high flux of incident electrons (ex. during geomagnetic sub-storm). As a result, different materials/components may experience a range of potentials which may lead to plasma-induced arcs, damaging spacecraft components. Graphene are emerging two-dimensional (2D) carbon materials with excellent physical and chemical properties, such as high conductivity, high tensile strength, high transparency, and high carrier mobility. These excellent properties make graphene potentially useful for applications in energy storage, aerospace, coatings and polymer markets and thermal protection. Substrates constituted by graphene harness the thermal and mechanical properties to create novel coatings with superior performance, hence broadening the graphene application spectrum. Of particular interest is the potential capability of graphene-based materials to provide increased protection against spacecraft charging in the space plasma environments. The work function of graphene can be tuned by either metal doping or functionalization, thereby increasing the electron yields and enhancing the possibility of emission through negative electron affinity. Within this context, Faraday Technology is working on developing an electrophoretic bath formulation and manipulate the pulsed electric field parameters to deposit graphene-based coatings onto test substrates, which may maintain integrity of spacecraft by autonomous electron emission in relevant environments. As shown in the Figure, uniform graphene-based coatings have been formed on an aluminum substrate. The coatings are characterized and evaluated by optical microscopy, scanning electron microscopy, and field-emission scanning electron microscopy. Faraday will also investigate the incorporation of metal particles into graphene film to tailor the emission properties, allowing for obtaining the low work function. The demonstrated technology not only addresses the desire to introduce novel manufacturing techniques for spacecraft charging mitigation, but also provides a scalable thin film and low-cost manufacturing process that has the potential of producing low reflective coatings. Acknowledgements: The financial support of DOD Air Force Contract No.: FA9453-19-P-0573 is acknowledged. Figure 1

Process Control of Pre-Sowing Seed Treatment by Pulsed Electric Field

Abstract Presented paper investigates the application of a line voltage changer to an installation for pre-sowing seed treatment by pulsed electric field (PEF) in order to increase the sowing quality of seeds and to suppress pathogenic microflora. The installation comprises an AC voltage regulator, a high voltage source, a voltage inverter, a working chamber for seed treatment, a control unit, and current and voltage sensors. The proposed installation differs from the existing apparatuses as it automatically provides the transformation of the pulsed electric field parameters by constant monitoring of power processes in a layer of treated seeds and feedback sending to the control unit. Seed treatment efficiency depends on the dose being determined by the parameters of electric field, namely, intensity in the seed layer, pulse duration, pulse repetition frequency, and seed treatment time. The parameters of rational treatment were determined, and the minimum treatment dose was calculated on the basis of results from the laboratory tests on the effect of pulsed electric field on sowing qualities of winter wheat seeds. It was experimentally confirmed that the proposed installation provides automatic transformation of electric field parameters depending on the changes taking place in the seed layer on the example of seeds with different moisture content maintaining the necessary treatment dose, ensuring the stability and repeatability of results.

Calcein Release from Cells In Vitro via Reversible and Irreversible Electroporation.

The aim of this study was to investigate the dependence of calcein extraction and cell viability on the parameters of pulsed electric field (PEF). Two different approaches concerning PEF parameters were investigated: (1) extraction efficiency and cell viability dependence on pulse number, exploiting 1200V/cm 100 µs duration high voltage (HV) electric pulses and (2) extraction efficiency and cell viability dependence on the pulses with different duration (44-400 µs) and electric field strength (600-1800V/cm) that result in the same amount of electric field energy delivered to Chinese hamster ovary cells. Extraction efficiency was evaluated as a percentage ratio of calcein fluorescence intensity prior and after PEF treatment. Cell viability was evaluated using PI test and cell clonogenic assay. Moreover, calcein release dynamics from cells after 600V/cm 400 µs, 1200V/cm 100 µs, and 1800V/cm 44 µs was evaluated. Our results show that HV pulses induce instant calcein extraction due to reversible electroporation; however, subsequent calcein leakage over time was only observed when 9 HV pulses of 1800V/cm 44 µs were used. The increased number of pulses resulted in more efficient total calcein extraction. With the same total energy delivered via electric pulses, the increase of calcein extraction efficiency was more dependent on pulse strength rather than pulse duration. The highest calcein extraction efficiency (84.5 ± 7.4%) was obtained using 9 electric field pulses of 1800V/cm, 44 µs at 1Hz. Furthermore, the extraction efficiency can be significantly enhanced if external mechanical stress (pipetting) is applied to cells. Cell viability was determined to be dependent on different PEF exposure parameters. It varied from 96.8 ± 4.8 to 31.2 ± 8.9%, implying the possibility to adjust PEF parameter combinations to maintain high cell viability.

Effect of Pulsed Electric Fields (PEF) on Accumulation of Magnesium in Lactobacillus rhamnosus B 442 Cells

The aim of this study was to determine the effect of pulsed electric fields (PEF) on accumulation of magnesium ions in Lactobacillus rhamnosus B 442 cells. Under optimized conditions, this is, on 15 min exposure of the 20 h grown culture to PEF of the 2.0 kV/cm and 20 µs pulse width at concentration 400 μg Mg2+/mL medium, accumulation of magnesium in the biomass reached maximum 4.28 mg/g d.m. Optimization of PEF parameters caused an increase of magnesium concentration in the cells by 220% in comparison to the control not treated with PEF. Bacterial cell biomass enriched with Mg2+ may be an alternative for pharmacological supplementation applied in deficiency of this cation.

Determination and analysis of the electrical components of a PEF treated equivalent circuit of potato tissue

The permeabilized membrane state of a pulsed electric field (PEF) treated biological sample is invisible to the naked eye, but can be deduced as the permeabilization causes loss of the insulating properties of the membrane, which can be determined by measuring the electrical impedance. This paper reports a spectroscopic analysis of a PEF treated and untreated potato sample to determine the electrical components of the biological tissue equivalent circuit model. The measurements concern flat potato samples which were subjected to different values of factors such as electric field, pulse number, pulse width and frequency. Cole–Cole plots are used to calculate the pore resistance and capacitance. This method of impedance measurement is used to establish the appropriate equivalent circuit model of the potato tissue according to the measured data, and thus explanations about the cell model from the impedance spectra are deduced. The PEF parameters had significant effect on the impedance and structural changes of the biological tissue. The treatment frequency does not have significant effect on the impedance when the electrical field, pulse number and width are kept constant.

Optimization Extraction of Protein from Mussel by High-Intensity Pulsed Electric Fields

High-intensity pulsed electric field (PEF) was used to extract protein from mussel. Results show that PEF extraction speed is much faster, and the extraction yield of protein is higher compared with traditional methods. Variation of PEF parameters and the extraction yield of protein were determined by single-factor experiments. The processing conditions were optimized by response surface methodology. The maximum extraction yield of protein of 77.08% was achieved under the following conditions: electric field intensity of 20 kV/cm, pulse number of 8 and enzymolysis time of 2 h. PEF can be widely used to extract protein with high speed and low pollution. Practical Applications Freshwater mussel is widely cultured in China and plays a very important role in aquaculture business. Recently, thanks to the nutritional value, advantages for human diets and edibleness as other shellfish such as shrimp, clam, lobster, scallop, abalone and crab, mussel is in growing value. It is valuable to exploit it. This study of PEF method to extract protein from mussel is important to utilize the mussel meat. PEF, with advantages of non-thermal performance, speediness, efficiency, low power and low pollution, is currently used for non-thermal pasteurization of food and extraction of value components from different natural sources. The results of this study are helpful to the further research of PEF method of protein extraction of mussel and, as such, are of practical significance.

Semi‐Bionic Extraction of Effective Ingredient from Fishbone by High Intensity Pulsed Electric Fields

AbstractSemi‐bionic extraction method and high intensity pulsed electric fields (PEF) were combined to rapidly extract effective ingredients (calcium, chondroitin sulfate and collagen) from fishbone. In order to simplify the analytical process, comprehensive index formula was determined by principal component analysis. Based on the principle of bionics, the optimal fluid pHs in human stomach, small intestine and large intestine are 2.0, 7.5 and 8.3. The simulated pHs were 2.0, 7.5 and 8.3, respectively, and variation of PEF parameters and the comprehensive evaluation index were determined by single factor experiments. Too low or too high liquid‐material ratio and electric field strength were not conducive to the comprehensive evaluation index Y. The value of Y increased with the increase of pulse number. The maximum contents of calcium, chondroitin sulfate and collagen in the extract were obtained simultaneously by response surface methodology (RSM), that is, 19.8, 39.268 and 3.875 mg/mL, respectively The optimum condition is as the following: liquid‐material ratio 11, electric field strength 22.79 kV/cm and pulse number 9.Practical ApplicationsSBE and PEF technique were combined to analyze the effective ingredients in fishbone. The prepared fishbone hydrolysate can be processed into multi‐active and high‐added‐value compound products suitable for absorption and utilization by the digestive tract. This paper provides a new technique for comprehensive utilization of fishbone and fishbone waste, serves as a new clue for processing and extraction of natural products and provides a basis for promotion of SBE and PEF.

Effects of high-frequency and high-voltage pulsed electric field parameters on water chain formation

Separation methods utilizing high-frequency and high-voltage pulsed DC electric fields have been used extensively in the oil and petroleum industries, where the occurrence of water-in-oil dispersions is highly unwelcome because of physical constraints and the high maintenance costs required to treat these dispersions. This paper reports the results of studies of the effects of applied electric field parameters, including electric field strength, frequency, and duty ratio, on water chain formation in water-in-oil emulsions. The investigations were performed in a rectangular Perspex® cell. The results of the studies show that dipole–dipole forces dominate the process of water chain formation. At low electric field strength, frequency, or duty ratio, dipole–dipole forces are negligible; therefore, the process of water chain formation and aqueous drop coalescence are inconspicuous. However, at high electric field strength, frequency, or duty ratio, significant dipole–dipole forces give rise to water chain formation and aqueous drop coalescence. At extremely high electric field strength, frequency, or duty ratio, aqueous drops are excessively polarized and disintegrate, inhibiting the processes of water chain formation and aqueous drop coalescence. The optimum electric field parameters for separation of water-in-oil dispersions are as follows: electric field strength, 3.80 kV cm−1; frequency, 4.0 kHz; and duty ratio, 0.65.

Pulsed electric field treatment of sugar beet tails as a sustainable feedstock for bioethanol production

Sugar beet tails are a sustainable feedstock for bioethanol production. This work discusses a new process to produce a fermentable juice of sugar beet tails using pulsed electric field (PEF) and solid–liquid expression. The impact of PEF intensity E and duration tPEF on the expression kinetics of solutes from sugar beet tails was investigated. The optimal PEF intensity and duration were respectively E=450V/cm and tPEF=10ms corresponding to an energy input Q=1.91Wh/kg. At these PEF parameters, the yield of solutes was increased from 16.8% to 79.85% and the dryness of pressed cake was increased from 15% to 24% in comparison with the untreated tails. Moreover, the PEF expressed juice was more concentrated (10% vs. 5.2%) and had higher sucrose content (8.9 vs. 4.5°S) than the juice expressed from untreated tails. Batch fermentation experiments with commercial Saccharomyces cerevisiae yeast were realized using raw juices expressed from untreated and PEF treated sugar beet tails. It was found that the higher content of fermentable sugars in PEF expressed juice leads to a higher ethanol content in distillate (6.1% vs. 2.95% v/v) and a higher CO2 weight loss (57.2 vs. 28.3g/L) than that obtained from raw juice of untreated tissue. The obtained results are promising and open new opportunities for valorization of sugar beet by-products.

Bioaccumulation of the Selected Metal Ions in Saccharomyces cerevisiae Cells Under Treatment of the Culture with Pulsed Electric Field (PEF).

The obtained results demonstrated an influence of PEF on increase in accumulation of various ions in S. cerevisiae cells. Optimization of particular PEF parameters and ions concentrations in the medium caused twofold increase in accumulation of magnesium and zinc ions and 3.5-fold higher accumulation of calcium ions in the cells. In the case of ion couple, accumulation of magnesium and zinc was, respectively, 1.5-fold and twofold higher in comparison to the control cultures. Yeast cells biomass enriched with Mg(2+), Zn(2+), Ca(2+) as well as Mg(2+) and Zn(2+) (simultaneously) may be an alternative for pharmacological supplementation applied in deficiency of these cations.

Application of Pulsed Electric Field for Oil Extraction from Sunflower Seeds: Electrical Parameter Effects on Oil Yield

AbstractThe application of pulsed electric field (PEF) as one of the nonthermal intensification methods has been proposed to increase oil yield extraction from sunflower seeds. PEF treatments have been carried out under various electrical parameters such as electric field, pulsed frequency, pulse width, time of treatment and sample conductivity. 55 fractional factorial design has been used for the analysis of the impact of PEF parameters on oil yield, and oil yield square model parameters have been investigated. The oil yield was found to increase by 9.1% after treatment of sunflower seeds by variation of PEF parameters: 30 s under an electric field of 7.0 kV/cm having frequency of 15 Hz, solvent content of 40 wt% and pulse width of 30 μs.Practical ApplicationsHere, we study the application of assisted pulsed electric field for oil extraction from sunflower seeds and we find the most effective variation of pulsed electric field parameters for treatment. It is very important in the industrial world as it deals with the time, quality of production and cost, which are usually carried out without preliminary treatment.

Skin rejuvenation with non-invasive pulsed electric fields.

Degenerative skin diseases affect one third of individuals over the age of sixty. Current therapies use various physical and chemical methods to rejuvenate skin; but since the therapies affect many tissue components including cells and extracellular matrix, they may also induce significant side effects, such as scarring. Here we report on a new, non-invasive, non-thermal technique to rejuvenate skin with pulsed electric fields. The fields destroy cells while simultaneously completely preserving the extracellular matrix architecture and releasing multiple growth factors locally that induce new cells and tissue growth. We have identified the specific pulsed electric field parameters in rats that lead to prominent proliferation of the epidermis, formation of microvasculature, and secretion of new collagen at treated areas without scarring. Our results suggest that pulsed electric fields can improve skin function and thus can potentially serve as a novel non-invasive skin therapy for multiple degenerative skin diseases.

Influential Mechanism of the HPEF Parameters on the Dielectric Properties of Fresh Vegetables

The pretreatment of fresh vegetables with HPEF can improve lyophilized speed and reduce energy consumption, but when people study how to use fresh vegetables dielectric properties online to monitor the change of lyophilized water, they need to consider the impact of parameters of high voltage pulsed electric field on dielectric properties of fresh vegetables. Therefore, according to the author's many years of study and practical experience, this study first analyzes the dielectric properties of fresh vegetables and then develops the required equivalent circuit of this study; finally, it focuses on the impact of the mechanism of pulsed electric field parameters. The result of this study will provide a useful reference to the treatment of fresh vegetables with the HPEF.

Microwave and pulsed electric field assisted extractions of polyphenols from defatted canola seed cake

SummaryThe incorporation of microwave and pulsed electric field (PEF) technologies in optimising the extraction of polyphenols from defatted canola seed cake was determined by Box‐Behnken response surface methodology, using three parameters of microwave treatment (power, time and liquid: solid (L:S) ratio) and four parameters of PEF (ethanol concentration, time, frequency and voltage). After microwave and PEF pretreatments, the polyphenols of defatted canola seed cake were extracted by ultrasound treatment under fixed variables (200 W of ultrasonic power, 70 °C of water bath and 20 min of extraction time). The measured responses were total phenolics, total flavonoids, the DPPH˙ scavenging activity and ferric reducing antioxidant power (FRAP). The maximum yields of all responses were achieved under optimum conditions of microwave processing (5 min, L:S ratio of 6.0 and 633.3 W) and PEF‐assisted extraction (30 V, 30 Hz, 10% ethanol concentration and 10 s).

A numerical investigation of the electric and thermal cell kill distributions in electroporation-based therapies in tissue.

Electroporation-based therapies are powerful biotechnological tools for enhancing the delivery of exogeneous agents or killing tissue with pulsed electric fields (PEFs). Electrochemotherapy (ECT) and gene therapy based on gene electrotransfer (EGT) both use reversible electroporation to deliver chemotherapeutics or plasmid DNA into cells, respectively. In both ECT and EGT, the goal is to permeabilize the cell membrane while maintaining high cell viability in order to facilitate drug or gene transport into the cell cytoplasm and induce a therapeutic response. Irreversible electroporation (IRE) results in cell kill due to exposure to PEFs without drugs and is under clinical evaluation for treating otherwise unresectable tumors. These PEF therapies rely mainly on the electric field distributions and do not require changes in tissue temperature for their effectiveness. However, in immediate vicinity of the electrodes the treatment may results in cell kill due to thermal damage because of the inhomogeneous electric field distribution and high current density during the electroporation-based therapies. Therefore, the main objective of this numerical study is to evaluate the influence of pulse number and electrical conductivity in the predicted cell kill zone due to irreversible electroporation and thermal damage. Specifically, we simulated a typical IRE protocol that employs ninety 100-µs PEFs. Our results confirm that it is possible to achieve predominant cell kill due to electroporation if the PEF parameters are chosen carefully. However, if either the pulse number and/or the tissue conductivity are too high, there is also potential to achieve cell kill due to thermal damage in the immediate vicinity of the electrodes. Therefore, it is critical for physicians to be mindful of placement of electrodes with respect to critical tissue structures and treatment parameters in order to maintain the non-thermal benefits of electroporation and prevent unnecessary damage to surrounding healthy tissue, critical vascular structures, and/or adjacent organs.

Removal of Organic Pollutants from Reverse Osmosis Concentrate by Electro-Fenton Process

The RO concentrate containing non-degradation organic pollutants was treated by electro-Fenton process. The high voltage pulse generator was used as discharge power. The effects of pulsed electric field parameters, aeration rate and pH on COD removal rate was investigated. The results indicate that the COD removal rate is up to 80.71% when pulsed voltage, pulsed frequency, treatment time, aeration rate and pH are 30000 V, 5 Hz, 240 s, 1.0 m3/h and 10, respectively.

Optimisation extraction of chondroitin sulfate from fish bone by high intensity pulsed electric fields

High intensity pulsed electric fields (PEF) was used to extract chondroitin sulphate (CS) from fish bone. Results show that PEF extraction speed is much faster, and the content of CS is much higher compared with traditional methods. Variation of PEF parameters and the content of CS were determined by single factor experiments. The processing conditions were optimised by quadratic general rotary unitised design experiments. The maximum yield of 6.92g/L was achieved under the following conditions: material–liquid ratio of 1:15g/mL, electric field intensity of 16.88kV/cm, pulse number of 9, and NaOH concentration of 3.24%. The purity of CS was analysed by agarose gel electrophoresis. CS purity was high, and the extract did not contain any other glycosaminoglycans. PEF can be widely used to extract CS with non-thermal performance, high speed, and low pollution.

Optimization and characterization of pulsed electric field parameters for extraction of quercetin and ellagic acid in emblica officinalis juice

A novel study has been optimized for the application of pulsed electric field (PEF) treatment (varying from 18 to 24 kV cm−1 for the duration 300–1,000 µs) on fresh emblica juice for extracting quercetin & ellagic acid which are considered as the major secondary metabolites in plant based foods. HPLC–PDA studies showed substantial increase (p < 0.05) in the PEF extracted levels of above metabolites in herb juice. It can be attributed to PEF induced vibrational disruption which increases the metabolic stress leading to emergence of these compounds. Both Raman and FTIR characterization, confirmed the presence of these in emblica juice. Electric field strength of 22 kV cm−1 was found to be optimum, where maximum cell disintegration index (0.79) was achieved during treatment time of 500 µs, which enhanced the amount of quercetin to about ninefolds and ellagic acid to about twofolds respectively, in comparison to untreated and thermally treated juice sample. However, a reverse trend was observed in thermally treated juice where degradation of the compounds (p < 0.05) was detected. Thus, PEF can be considered as a viable medium for extracting intracellular metabolites, thereby incrementing the functional potential of emblica juice.

Structural and Biochemical Changes Induced by Pulsed Electric Field Treatments on Cabernet Sauvignon Grape Berry Skins: Impact on Cell Wall Total Tannins and Polysaccharides

Pulsed electric field (PEF) treatment is an emerging technology that is arousing increasing interest in vinification processes for its ability to enhance polyphenol extraction performance. The aim of this study was to investigate the effects of PEF treatment on grape skin histocytological structures and on the organization of skin cell wall polysaccharides and tannins, which, until now, have been little investigated. This study relates to the effects of two PEF treatments on harvested Cabernet Sauvignon berries: PEF1 (medium strength (4 kV/cm); short duration (1 ms)) and PEF2 (low intensity (0.7 kV/cm); longer duration (200 ms)). Histocytological observations and the study of levels of polysaccharidic fractions and total amounts of tannins allowed differentiation between the two treatments. Whereas PEF1 had little effect on the polyphenol structure and pectic fraction, PEF2 profoundly modified the organization of skin cell walls. Depending on the PEF parameters, cell wall structure was differently affected, providing variable performance in terms of polyphenol extraction and wine quality.