Electric Field Treatment Research Articles

Influence of pulsed electric field treatment on the fate of Fusarium and Alternaria mycotoxins present in malting barley

Mycotoxin contamination of cereals is a global problem. Different decontamination technologies are in use today, from simple non-destructive ones such as sorting and sieving, to more sophisticated physical methods exploiting irradiation, ultrasound, cold plasma or a pulsed electric field (PEF). The current study focuses on characterizing the effect of PEF on mycotoxins present on malting barley. The degradation potential, as well as changed extractability into the electrolyte (water) after PEF treatment was assessed for 16 common and emerging Fusarium and Alternaria mycotoxins, using ultra-high performance liquid chromatography coupled with high-resolution tandem mass spectrometry. The presence of degradation/transformation products was screened for in the samples after in silico prediction. The overall PEF-induced reduction in trichothecenes, zearalenone, enniatins, beauvericin, and tentoxin, calculated based on the dry matter of barley, was up to 31, 48, 84, 36 and 46%, respectively. For the majority of mycotoxins, decreases were also observed in water, whereas for type A trichothecenes, zearalenone, enniatins, and beauvericin, increases up to 130, 123, 629 and 192% occurred, probably associated with facilitated extraction from the matrix (100% = mycotoxins rinsed into water independent of PEF treatment). The degradation/transformation products of mycotoxins were mostly the result of hydrolysis, elimination and/or oxidation.

Experimental and simulation-based investigation of the interplay between factor gradients following pulsed electric field treatments triggering whey protein aggregation

Novel pulsed electric field (PEF) applications to modify the techno-functionality of biomacromolecules have recently emerged. Insights into the involved interplay of factor domains (electrical, flow, concentration, temperature) with respect to the treatment chamber locations, and into the scalability are lacking. Therefore, a parallel plate batch (0.8 mL) and a scaled up parallel plate continuous (50 mL, 0.83 mL s −1 ) setup were built and simulated to investigate these domains and resulting gradient interactions using liquid whey protein solutions (0.5% w/w). In both setups, protein agglomerations and aggregations were observed below 60 °C at the electrode boundary layers for pulses in the range of 2–2.5 kV cm −1 , 10 μs, 40–350 Hz. The boundary layer is characterized by higher protein concentrations due to temperature- and pH-dependent migration trajectories, increased electrochemical reactivity (e.g., pH), and increased residence times due to the laminar flow or no flow conditions. Characterizing the domain interconnectivity led to effective scaling-up approaches of protein aggregations and insights into involved mechanisms. • Pulsed electric fields trigger whey protein migration and aggregations below 60 °C. • Identified regimes might provide a new process window to alter techno-functionalities. • Migration direction and aggregation location are pH-dependent. • Translation of observations from a batch to a scaled up continuous system. • Reactive boundary layer is characterized by overlaying factor domains and gradients.

Tunable phase structure in NaNbO3 ceramics by grain-size effect, electric field and heat treatment

Large polarization and strain change during antiferroelectric - ferroelectric phase transition under electric field is the foundation for realizing excellent electrical properties in antiferroelectric ceramics, therefore, the adjustment of antiferroelectricity and clarification of the corresponding mechanism is the foundation for controlling electrical properties. NaNbO3 is the most complex perovskite system showing multiple antiferroelectric phases in a wide temperature range, in which the antiferroelectricity shows obvious instability with changing external and internal conditions, namely the antiferroelectric phase can be adjusted by grain-size effect, electric field and heat treatment. According to the systematical study in terms of the Rietveld refinement of synchrotron XRD and Raman, NaNbO3 exhibits a ferrielectric P21ma structure at room temperature, the ferroelectric component of which increases with decreasing grain size. Two antiferroelectric tetragonal phases exist around Curie temperature TC before the entrance of antiferroelectric R phase zone, while an antiferroelectric monoclinic phase, which can be maintained to room temperature by annealing treatment, acts as the bridge for the depolarization of the poled NaNbO3 with ferroelectric Q phase. A detailed phase diagram mainly focused on the antiferroelectric phase zones of NaNbO3 is plotted, which gives a clear understanding about the polymorphic phase transitions under different conditions. The results concluded in this work would give a clear guidance for designing high-performance NaNbO3-based lead-free ceramics from the point of structure.

Electric field efficiently enhanced thermochemical cleaning for oil recovery from oily sludge

Electric field efficiently enhanced thermochemical cleaning for oil recovery from oily sludge (OS) was proposed in this work, which was inspired by electro-kinetic (EK) remediation of sludge. The effects of different factors (e.g., current density, the concentration of solution, liquid to solid ratio) on oil removal efficiency of OS were investigated. It was found that the oil removal efficiency of OS could reach more than 60 wt% by electric field enhanced the instability of metastable emulsion system with a minimum energy consumption of 604.8 J/g. The content of the residual oil in the sludge could be lowered from 8.6 wt% to 2.8 wt% after being treatment under the optimum conditions, which showed a 143 wt% maximum increase in oil removal effiency compared to non electric field treatment. The recovered oil mainly consisted of long chain alkanes, which had high recovery value. Based on characterization and analysis results, the mechanism was speculated to provide guidance for the resource utilization of OS with low energy consumption in industrial processing.

Using electric field to modify wet gluten as meat analogue material: A comparative study between pulsed and direct current electric fields

To assess the efficacy of electric field (EF) on vegetable protein juice-holding and texturisation as a low denaturation processing means, the impacts of pulsed (PEF) and low direct current (DCEF) electric field on the water- (WHC) and oil-holding capacity (OHC), microstructure, texture and physical structure of wheat gluten were investigated using wet gluten dough. The results showed that the PEF and DCEF affected the WHC and OHC significantly. The PEF seemed not to affect the textural properties so severely although significant differences appeared in hardness, chewiness, gumminess, and cohesiveness; there were no significant differences either in springiness or in resilience. The DCEF had a stronger impact on all the textural indices. Scanning electronic microscopy suggested that the PEF caused smaller and uniform micropores and the DCEF derivated more continuous and compact microstructure. Fourier transform infrared spectrometry demonstrated that EF significantly altered the composition proportion of the secondary structure. A slight blue shifts of UV spectra, a red shift of fluorescence spectra, and an increased surface hydrophobicity of gluten could be observed after EF treatment. X-ray diffractometry demonstrated that the EF significantly made the physical structure of wet gluten compacter. The results suggested that EF is promising in vegetable protein texturisation.

Production of cyclosporin A by Tolypocladium inflatum using dairy waste medium: optimization and investigation of the effect of ultrasound, high hydrostatic pressure, and pulsed electric field treatments on the morphology of fungus

Production of cyclosporin A by Tolypocladium inflatum using dairy waste medium: optimization and investigation of the effect of ultrasound, high hydrostatic pressure, and pulsed electric field treatments on the morphology of fungus

Tenderization of Beef Semitendinosus Muscle by Pulsed Electric Field Treatment with a Direct Contact Chamber and Its Impact on Proteolysis and Physicochemical Properties.

In this study, the effects of pulse electric field (PEF) treatment on the tenderization of beef semitendinosus muscle were investigated. An adjustable PEF chamber was designed to make direct contact with the surface of the beef sample without water as the PEF-transmitting medium. PEF treatment was conducted with electric field strengths between 0.5 and 2.0 kV/cm. The pulse width and pulse number were fixed as 30 μs and 100 pulses, respectively. The impedance spectrum of PEF-treated beef indicated that PEF treatments induced structural changes in beef muscle, and the degree of the structural changes was dependent on the strength of the electric field. Cutting force, hardness, and chewiness were significantly decreased at 2.0 kV/cm (35, 37, and 34%, respectively) (p < 0.05). Troponin-T was more degraded by PEF treatment at 2.0 kV/cm intensity (being degraded by 90%). The fresh quality factors such as color and lipid oxidation were retained under a certain level of PEF intensity (1.0 kV/cm). These findings suggest that PEF treatment could tenderize beef texture while retaining its fresh quality.

Nanosecond bacteria inactivation realized by locally enhanced electric field treatment

Bacterial contamination in water is still a critical threat to public health; seeking efficient water disinfection approaches is of great significance. Here we show that locally enhanced electric field treatment (LEEFT) by electrodes modified with nanoscale tip structures can induce ultrafast bacteria inactivation with nanosecond electrical pulses. A lab-on-a-chip device with gold nanowedges on the electrodes is developed for an operando investigation. Attributed to the lightning-rod effect, the bacteria at the nanowedge tips are inactivated by electroporation. A single 20 ns pulse at 55 kV cm−1 has achieved 26.6% bacteria inactivation, with ten pulses at 40 kV cm−1 resulting in 95.1% inactivation. LEEFT lowers the applied electric field by about 8 fold or shortens the treatment time by at least 106 fold, compared with the system without nanowedges. Both Gram-positive and Gram-negative bacteria, including antibiotic-resistant bacteria, are inactivated with nanosecond pulses by LEEFT. According to simulation, when the membrane of the cell located at the nanowedge tip is directly charged by the concentrated charges at the tip, it is charged much faster and to a much higher level, leading to instant electroporation and cell inactivation. Efficient ways to disinfect water from bacterial contamination are essential for public health. Locally enhanced electric field treatment can be used to induce ultrafast bacteria inactivation with nanosecond electrical pulses.

Influence of electrical process parameters to inactivate microorganisms in orange juice by PEF technology

Pulsed electric field (PEF) is a non-thermal/chemical food processing method for microbial inactivation in liquid food. This method finds its application to prolong the shelf-life of the seasonal fruit juices which helps to maintain the supply chain throughout the year. So, in the present study, the most commonly found microorganisms of Escherichia coli (E. coli), Staphylococcus aureus (S.aureus) and Saccharomyces cerevisiae (S.cerevisiae) inoculated in orange juice are considered. PEF impact on microbial inactivation based on the experimental results are analyzed with respect to pulse frequency, electric field intensity and treatment time. The PEF treatment conditions set for the investigation are as follows. Electric field intensity: - 5 kV/cm and 10 kV/cm; Pulse frequency: - 1, 10, 20 and 50 kHz; Pulse width: - 1.2 µs; Treatment time: - 10 s, 20 s, 30 s, 40s and 50s. A maximum inactivation of log10 reduction 2.62 ± 0.122 is observed when E. coli was subjected to 10 kV/cm at 50 kHz. Meanwhile S.cerevisiae and S.aureus are inactivated at the level of log10 reduction 2.4 + 0.16 and 2.1 + 0.9 respectively at the same treatment conditions when the treatment time is 50 s. It is also observed that the electric field intensity along the higher frequency enhances the inactivation level of microorganisms and the variations in the log reduction might be due to the different biological structure of the microorganisms.

Methods for improving meat protein digestibility in older adults

This review explores the factors that improve meat protein digestibility and applies the findings to the development of home meal replacements with improved protein digestion rates in older adults. Various methods improve the digestion rate of proteins, such as heat, ultrasound, high pressure, or pulse electric field. In addition, probiotics aid in protein digestion by improving the function of digestive organs and secreting enzymes. Plant-derived proteases, such as papain, bromelain, ficin, actinidin, or zingibain, can also improve the protein digestion rate; however, the digestion rate is dependent on the plant enzyme used and protein characteristics. Sous vide processing improves the rate and extent of protein digestibility, but the protein digestion rate decreases with increasing temperature and heating time. Ultrasound, high pressure, or pulsed electric field treatments degrade the protein structure and increase the proteolytic enzyme contact area to improve the protein digestion rate.

Electric field promotes dermal fibroblast transdifferentiation through activation of RhoA/ROCK1 pathway.

With the increased incidence of age-related and lifestyle-related diseases, chronic wounds are sweeping the world, where recent studies reveal that dysfunction of fibroblast plays an indispensable role. Endogenous electric field (EF) generated by skin wound disrupting an epithelial layer has been used as an alternative clinical treatment in chronic wound by modulating cellular behaviours, including fibroblasts transdifferentiation. Although many molecules and signaling pathways have been reported associated with fibroblasts transdifferentiation, studies investigating how the electric field affects the cellular pathways have been limited. For this purpose, a model of electric field treatment in vitro was established, where cells were randomly divided into control and electrified groups. The changes of protein expression and distribution were detected under different conditions, along with Zeiss imaging system observing the response of cells. Results showed that fibroblast transdifferentiation was accompanied by increased expression of a-SMA and extracellular matrix (COL-1 and COL-3) under the EF. Simultaneously, fibroblast transdifferentiation was also consistent with changes of cell arrangement and enhanced motility. Furthermore, we found that electric field activated RhoA signaling pathways activity. Y-27632, a RhoA inhibitor, which was used to treat fibroblasts, resulted in reduced transdifferentiation. The connection between electric field and RhoA signaling pathways is likely to be significant in modulating fibroblast transdifferentiation in acute injury and tissue remodeling, which provides an innovative idea for the molecular mechanism of EF in promoting chronic wound healing.

Optimization and simulation of pulsed electric field treatment chamber for food sterilization

Optimization and simulation of pulsed electric field treatment chamber for food sterilization

An electric-field instrument for accelerated aging to improve flavor of Chinese Baijiu

Chinese Baijiu is a traditional distilled spirit that is consumed abundantly in China and around the world. Aging would dramatically increase the flavor of Baijiu, and famous Baijiu usually needs the long storage time for aging. Therefore, artificial aging that could accelerate the flavor improvement is in high demand. In this study, an electric-field treatment device was developed for the electric-field aging of the liquor. We used three types of strong-flavor crude Baijiu from different manufacturers in Sichuan as samples for electric-field aging. The total acids and esters, volatile flavor components, and sensory evaluation of the Baijiu samples before and after treatment were determined. It was found that the total acids and total esters of the Baijiu samples decreased and increased, respectively, with aging. The composition of volatile components changed after the aging treatment, and the volatile flavor components associated with the changes in the quality of Baijiu were analyzed. Combined with the sensory evaluation results, it was concluded that the quality of the treated Baijiu was significantly improved via electric-field aging. The result showed that electric-field aging can be an effective way to improve the flavor of Baijiu.

Improvement of the probiotic growth-stimulating capacity of microalgae extracts by pulsed electric fields treatment

This study aimed to investigate the nutritional character (carbohydrates, proteins, pigments, and phycocyanin), total antioxidant capacity (TAC) and the capability of simulating the growth of Lactobacillus rhamnosus of different extracts from C. vulgaris and A. platensis by means of the application of conventional aqueous extraction procedure and pulsed electric field (PEF) extraction technology. It was confirmed a significantly improved nutritional profile of Chlorella and Spirulina extracts obtained by PEF technology pre-treatment (3 kV/cm, 100 kJ/kg), with specifically higher values in total carbohydrate, Chlorophyll a, Chlorophyll b, and carotenoids content, and TAC. Additionally, Spirulina PEF extract showed a probiotic's growth-stimulating capability of 1 log10 cycle when fermented by Lactobacillus rhamnosus, with a metabolomic profile specifically rich in bioactive short chain fatty acids (SCFAs) and organic acids (3-phenyl lactic acid). The present study points out the applicability of PEF extraction technology under optimized conditions to improve the nutritional and functional character of microalgae and cyanobacterial-derived ingredients.

Direct transesterification of microalgae after pulsed electric field treatment

AbstractBACKGROUNDLipid extraction is a major bottleneck for the commercialization of microalgae due to energy costs involved during solvent recycling. Direct transesterification offers the possibility to bypass the extraction step by immediately converting the lipids to fatty acid methyl esters (FAMEs). In this study, the efficiency of direct transesterification after pulsed electric field (PEF) treatment was evaluated. Freshly harvested Auxenochlorella protothecoides (A. protothecoides), cultivated either autotrophically or mixotrophically, was subjected to PEF. Two treatment energies were tested, 0.25 and 1.5 MJ kgdw−1, and results were compared with those for conventional two‐step transesterification.RESULTSFor autotrophically grown A. protothecoides, the percentage of the total FAMEs recovered from untreated biomass and microalgae treated with 0.25 MJ kgdw−1 was 30% for both cases, while for 1.5 MJ kgdw−1 it was 65%. A 24 h incubation step between PEF treatment and direct transesterification significantly improved the results. Untreated biomass remained stable with 30% of FAMEs, while with both treatment energies a 97% FAME recovery was achieved. However, for mixotrophic A. protothecoides the process was not as effective. Approximately 30% of FAMEs were recovered for all three conditions immediately after PEF with only a marginal increase after incubation. The reason for this different behavior of the two cultivation modes is unknown and under investigation.CONCLUSIONSOverall, the synergy between PEF and direct transesterification was proven to have potential, in particular for autotrophic microalgae. Its implementation and further optimization in a biorefinery therefore merit further attention. © 2022 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry (SCI).

Influence of High Hydrostatic Pressure and Pulsed Electric Field Treatment on Moisture Absorption of Wheat Grains

AbstractThe effect of high pressure (0.1–600 MPa) and pulsed electric field (E = 3 and 6 kV cm−1) pretreatments on the moisture absorption properties of non‐hulled wheat grains were investigated. Microwave sensor was used as a non‐invasive technique for determination of the moisture content. The results demonstrated that high pressure soaking (&gt;100 MPa) of wheat grains significantly increased the water uptake. High pressure soaking (600 MPa) decreased the water uptake due to the starch gelatinization and as a result appearance of structural changes. Compared to control samples, PEF‐pretreated samples showed a sharp increase of water absorption at the initial process with a further reduction of equilibrium water content. Peleg's water absorption model was adapted to the measured data of non‐hulled wheat grains. Results showed a good prediction of Peleg's equation in all experiments, which gave the possibility for estimation of initial water absorption rate and equilibrium moisture content.

Understanding the influence of PEF treatment on minerals and lipid oxidation of wet- and dry-aged venison M. longissimus dorsi muscle

Pulse electric fields (PEF) treatment can be used to improve meat quality attributes, such as tenderness and mass transfer kinetics of dry ageing of meat. This study investigated the effect of PEF (high-PEF 10 kV, 50 Hz, 20 μs; low-PEF 2.5 kV, 50 Hz, 20 μs) and ageing method (wet- and dry-ageing) on venison mineral profiles, and lipid and conjugated linoleic acid (CLA) oxidative stability. Twelve loins from six red deer were assigned to six groups: no-PEF dry-aged control, no-PEF control, wet-aged Low-PEF, dry-aged Low-PEF, dry-aged High-PEF, wet-aged High-PEF. Secondary oxidation products contents were not affected by PEF treatment (p > 0.05), but were affected by dry ageing (p < 0.05). CLA was stable across PEF treatments and different ageing regimes (p > 0.05). PEF treatments did not have any effect on minerals (p > 0.05). This study validates the safety of using PEF in venison processing with limited detrimental oxidative modifications.Industrial relevance - PEF treatment and the dry-ageing regimes applied to venison in the present study did not produce excessive oxidative by-products that could compromise product quality. The application of both PEF treatments (HPEF 10 kV, 50 Hz, 5 μs; LPEF 2.5 kV, 50 Hz, 5 μs) could potentially improve the drying of venison with a low risk of increasing oxidation.

The effects of pulsed electric fields treatment on the structure and physicochemical properties of dialdehyde starch

The structural and physicochemical properties changes of corn starch oxidized by sodium periodate under the assistance of pulsed electric fields (PEF) were studied. It was found that dialdehyde starch (DAS) particles produced by PEF-assisted oxidation exhibited shrinkage and pits, and had a larger particle size when compared to the control without PEF. The solubility of the DAS (12 kV/cm PEF- assisted oxidation) improved by 70.2% when compared to the native starch. Increment in the strength of the PEF, led to a decrease in the viscosity of the DAS. In addition, the aldehyde group content of the DAS produced by PEF-assisted oxidation exhibited shrinkage and pits, and had a larger particle size when compared to the control increased by 11.6% when compared with the traditional oxidation method. PEF is an effective method to promote oxidation reaction of starch.

Pulsed Electric Field Processing of Red Wine: Effect on Wine Quality and Microbial Inactivation

Pulsed electric field (PEF) treatment of red wine samples with energies changing from 2.4 to 13.2 kJ to inactivate Saccharomyces cerevisiae, Hansenula anomala, Candida lipolytica, Lactobacillus delbrueckii ssp. bulgaricus, and Escherichia coli O157:H7 with the determination of the changes in the quality and sensory properties in addition to metal ion concentration (Na, Mg, K, and Mn) were explored. Increased applied energy resulted in a significant increase in pH, conductivity, lightness (L*), yellowness (b*), and total phenolic substance content with significant inactivation of all microorganisms with no significant change in metal ion concentration. Sensory properties of particle status, sour taste, and aftertaste were significantly decreased, whereas the other measured properties were significantly increased by 13.2 kJ PEF treatment (p &lt; 0.05). Joint optimization studies for the most optimal processing parameters for the measured properties were 488 s, 0.13 kJ, and 0.22 kV; 488 s, 13.2 kJ, and 31 kV; 348 s, 9.39 kJ, and 31 kV/cm; and 488 s, 13.2 kJ, and 0 kV EFS, with 0.79, 0.69, 1.00, and 0.72 composite desirability, respectively.

Modelling of a Resonant Charging Circuit for a Solid-State Marx Generator

For the pulsed electric field treatment of plant material on an industrial scale, Marx-type pulse modulators are used as a pulse source. The combination of a conventional Marx generator design equipped with solid-state switches with the concept of resonant charging via current-compensated chokes enables the set-up of a Marx generator having only one active semiconductor switch per stage. Thereby, the pulse shape is defined by the passive components of the RLC-pulse circuit. In the course of the design of such a resonant charging circuit, common-mode current components through the current-compensated chokes need to be considered. Moreover, especially for a generator having its ground connection at its centre, induced voltages versus ground need to be addressed. Therefore, an investigation based on circuit simulations has been made. The simulations showed that the common-mode current components decay to zero just after the resonant charging process and cause a voltage transient at the terminal of the power supply, which needs to be floating versus ground. In order to reduce the amplitude of this transient, the effects of adding a damping resistor have been studied. However, adding this resistor may involve an increase in the common-mode current components. Moreover, the common-mode current components of different chokes are influenced by the on-time of the switches. In the paper, based on the simulation results, different operation modes with and without the damping resistor are discussed. Thereby, the on-time of the switches has been varied. Selected simulation results have been verified by means of measurements.