High Voltage Electrical Discharges Research Articles

High voltage electrical discharges followed by deep eutectic solvents extraction for the valorization of pomegranate seeds (Punica granatum L.)

This work proposes a sustainable methodology based on the use of high voltage electrical discharges (HVED) and deep eutectic solvents (DES) for the simultaneous extraction of proteins and polyphenols from pomegranate seeds. Pomegranate seeds were firstly pretreated with HVED and, next, submitted to a solid-liquid extraction using DES. HVED pretreatment was compared with ultrasounds observing a better performance of HVED that promoted the disintegration of 86% of cells at 160 kJ/kg energy input and, consequently, the release of 70% of proteins and 78% of polyphenols. Extraction/solubilization of proteins and polyphenols was carried out using 5 different DES and results were compared with the obtained using NaOH. DES improved the diffusivity of both proteins and polyphenols, although the highest rates were observed for proteins, while NaOH extracted higher amounts of both. Application of RP-HPLC-ESI-Q-TOF to the analysis of extracts enabled to identify 30 different phenolic compounds among extracts, most of them ellagitannins. Proteomics enabled to identity a total of 11 different proteins among pomegranate seed extracts that were mainly assigned to globulins and albumins, with nutrient reservoir activity.

Electrode Erosion During High-Voltage Electrical Discharge in a Liquid

The paper presents the results of experimental studies of the mass value of electrode (anode) erosion during a high-voltage electric discharge in a liquid. The results obtained made it possible to determine the influence of technological parameters and operating conditions of high-voltage electric discharge installations on the mass erosion of an anode. It is noted that with an increase in the specific electrical conductivity of the working fluid and in the length of the interelectrode gap, a decrease in the value of the mass erosion of the anode is observed. Comparison of mass erosion of anodes made of copper, steel, and aluminum showed that among them the steel anode has the highest erosion resistance during an electric discharge in water. Based on the results of the performed experimental studies, an empirical technique was developed that allows to estimate the mass erosion of the anode in one electric discharge in water.

Experimental Study of the Structural Damage to Coal Treated by a High-Voltage Electric Pulse Discharge in Water

Experimental Study of the Structural Damage to Coal Treated by a High-Voltage Electric Pulse Discharge in Water

Recent advancements in baking technologies to mitigate formation of toxic compounds: A comprehensive review

Conventional hot air baking is a widely used food processing technology, which involves simultaneous heat and mass transfer processes. Chances of acrylamide and hydroxymethylfurfural formation is high in baked products due to high-temperature treatment. Since acrylamide and hydroxymethylfurfural are harmful to human health, it becomes crucial to develop novel baking technologies to mitigate these harmful components without affecting the sensorial properties of the final baked product. The formation of hydroxymethylfurfural and acrylamide are closely related to baking temperature, baking time, and ingredients. Novel technologies and pretreatments are shown promising results to mitigate these harmful components in the end products. This review describes the suitable pretreatment methods, novel baking technologies, and effective post-baking techniques that help mitigate the development of harmful compounds without affecting the textural attributes of baked products. Novel baking technologies, such as vacuum baking, high voltage electrical discharge, supercritical carbon dioxide extrusion process, power ultrasound, infrared, microwave and halogen lamp baking; different pretreatment technologies – ozone treatment, plasma treatment, high-pressure processing, ohmic heating, ultraviolet irradiation and ligh emitting diode treatment are discussed together with a comprehensive insight to the understanding of mechanisms involved in the formation of harmful components during processing and post-baking. • Mechanism of baking and heat transfer reactions occurred in baking are summarized. • Effect of pre-treatments on the harmful compounds in final baked product is discussed. • Application of novel baking technologies is outlined. • There is a miles away to produce healthier baked products with minimal toxic component.

Virgin olive oil processing by high voltage electrical discharge or high hydrostatic pressure

We test the application of two emerging technologies to virgin olive oil (VOO) processing. high voltage electrical discharge (HVED) was tested at 20 kV and about 100 kJ/kg of VOO. High-pressure processing (HPP) was applied for 360 s at about 600 MPa. VOO quality indices were evaluated immediately after treatment and after 6 months. The HPP treatment was found to have no negative influence on any aspect (p > .05 according to General Linear Model and the Tukey HSD test). The HVED treatment did not affect conventional quality indices (p > .05), but was consistent with the appearance of secondary oxidation products (anisidine value increment of about 50% and rDigs increment of roughly 200%, both at p ≤ .05), a significant fall in biophenol concentrations roughly from 5 to 10% at p ≤ .05; and a decrease of about 15% at p ≤ .05 in positive volatiles. Overall, HVED processing appears to negatively impact VOO quality. Novelty impact statement For the first time, high voltage electrical discharge (HVED) has been tested on virgin olive oil (VOO) in comparison to high-pressure processing (HPP) over a storage period While HPP was entirely safe for VOO quality, HVED determines a potential detrimental effect Our findings support the application of these technologies to food containing VOO, or for its direct treatment, for instance, to protect against microbial spoilage.

From the Chief Executive and IFST News

From the Chief Executive and <scp>IFST</scp> News

Pulsed high-voltage electrical discharges in water: The resource for hydrogen production and water purification

The high-voltage electrical pulses with magnitude up to 200 kV, generated in water, are studied experimentally. These pulses are the water sample saturation result by less powerful pulses with magnitude of 10 kV and higher frequency. The pulse generation process is accompanied by release of hydrogen from water into environment. Besides, the considered complex of two dischargers generates electricity, the power of which exceeds the input power. Proposed the hypothetical mechanism of the process based on successive acts of acceleration and thermalization of protons. The results of wastewater treatment by generated high-voltage pulses are also presented.

The Effect of High Voltage Electrical Discharge on the Physicochemical Properties and the Microbiological Safety of Rose Hip Nectars.

Although neglected as an industrial raw material, rose hip has been important for both nutritional and medical purposes for centuries. The main goal of this study was to propose a rapid and inexpensive non-thermal technique such as high voltage electrical discharge (HVED) to preserve valuable rose hip bioactive compounds, towards the development of high-quality products, including low-calorie products. The objective of this work was to evaluate the effects of HVED on the physicochemical properties and the microbiological safety of rose hip nectar formulations and, for comparison, on a pasteurised sample. Physicochemical analysis proved that rose hip pulp and the prepared nectars were valuable sources of polyphenols and ascorbic acid with high antioxidant activity. The HVED technique had minimal effects on the quality characteristics of the nectars under the different process conditions (50, 100 Hz; 10, 15, 20 min). In addition, the pasteurised nectar showed the greatest loss of ascorbic acid (54%) and phenolic compounds (40%). The microbiological quality of nectars was examined immediately after preparation/treatment and after 6 and 12 days of storage at 4 °C. In addition to the pasteurised sample, HVED-treated rose hip nectar prepared from microwave-blanched puree with extended shelf life had satisfactory microbiological safety after storage.

Valorization of cocoa shell: Impact of high voltage electrical discharge and drying technology on properties of cocoa shell

There is a growing interest for use of cocoa shell for the enrichment of different food products and for resolving problem of disposal of shell. High voltage electrical discharge (HVED) is a non-thermal technology that could solve problems linked to use of cocoa shell (contaminants and undesirable components). This paper investigated the broader impact of HVED on the properties of cocoa shells and how much influence drying (freeze- and oven- drying), which needs to be conducted, actually has on these properties. After the treatments, oil binding capacity increased in freeze-dried samples from 1.598 to 2.054 g/g. Also, water was easier to remove from HVED-treated oven-dried samples (by 1.75%). HPLC analysis showed that HVED caused better preservation of (−)-epicatechin and (−)-epicatechin gallate after oven-drying. Klason lignin contents slightly increased and differential scanning calorimetry showed higher thermostability of cocoa shell especially after HVED and freeze-drying because peak shifted for 11.54°C. Practical applications Cocoa shell is a valuable by-product of the chocolate industry, and it presents a problem for the environment. High voltage electrical discharge (HVED) would be a sustainable solution for this problem. After the HVED treatment, drying process is needed, and this study presents insights in a combination of these two technologies on cocoa shell properties. These results show that cocoa shells can be modified with these processes and are suitable for application in different food products.

Microemulsion as solvent for naphthoquinones extraction from walnut (Juglans mandshurica Maxim) green husk using high voltage electrical discharge

• An efficient method for obtaining naphthoquinones from walnut husk was developed. • High voltage electric discharge extraction with microemulsion was explored. • The effects of microemulsion formula and discharge conditions were investigated. • High voltage electric discharge with microemulsion shows favorable superiority. Walnut green husks are a good source of natural naphthoquinones (NQs). In this study, a novel extraction strategy combining microemulsion and high voltage electric discharge (HVED) was proposed to extract the NQs from walnut green husks and maximize the value of this agro-byproduct. Firstly, the optimum microemulsion formula (ME8) for NQs extraction was determined among 17 microemulsions prepared with various contents ratios. Then the single factor experiments were conducted to explore the effect of discharge parameters (voltage, treatment time, liquid-solid ratio) on NQs yield. These parameters were further optimized by response surface methodology with Box-Behnken design, and the highest yield of NQs (67.1 ± 0.3 mg/g) was obtained under the predicted optimal conditions. The combination of HVED and microemulsion showed favorable synergistic preponderance and the NQs yield was 1.52 times higher than heating reflux extraction. Moreover, this strategy presented a competitive option to extract hydrophobic compounds in a less-organics-consumption way.

Using the electrohydraulic impact method to obtain manure fertilizers

Currently, animal husbandry and poultry farming waste, cattle and pig manure, bird droppings are prohibited to be exported to the fields and used as fertilizer without pretreatment. The standard disinfection process is reduced to composting, which takes 3-12 months. A promising direction of intensification of animal waste processing is the creation of a specially formed pulsed high-voltage electric discharge inside the liquid volume. Under the influence of which the microbial flora – bacteria and fungi - intensively dies. Specialists of the SPA “Spiral” have developed a pilot plant for manure treatment. The test results showed that coliform and Enterobacteria, including dysentery bacillus, were completely destroyed after processing a sample of cattle manure by the EGI method.

Extraction of phenolic compounds from oregano using high voltage electrical discharges–sustainable perspective

SummaryThe aim of the study was to observe the sustainability parameters of high voltage electrical discharge (HVED) as a novel technology for extraction of phenolic compounds from oregano. The life cycle assessment (LCA) of HVED was evaluated and compared with conventional extraction methods–infusion and maceration. The results showed that HVED extraction with nitrogen gave 2.19%–34.04% higher yield of phenolic compounds compared to infusion and 6.13%–90.95% higher yield compared to maceration, depending on the voltage and treatment time used for HVED. The environmental pillar of LCA, assessed by global warming potential, ranged from 1.130 to 4.635 kg CO2e for HVED samples treated with nitrogen and from 1.207 to 4.487 kg CO2e for samples treated with argon, which was mainly related to the duration of treatment. Other pillars of sustainability, namely society, economy, food safety and quality, were discussed. HVED was found to be the more sustainable technology (based on the results from LCA), with prospects for future scale‐up for the food industry.

Effect of high-voltage electrical discharge treatment on multi-element content in cocoa shell and chocolates with cocoa shell

Cocoa shell is rich in bioactive components, but also contains significant amounts of micro and macro elements, but also toxic elements. In this study, we examined the contents of different elements in cocoa shell, cocoa mass and the effect of high voltage electrical discharge (HVED) on the contents of these elements in the cocoa shell. Also, dark and milk chocolates were produced with different contents of untreated and HVED treated cocoa shell for which was also conducted ICP-MS analysis of these elements. HVED treatment caused a decrease in potassium, cadmium, uranium, cobalt, nickel, iron, molybdenum, chromium, manganese and copper content. The analysis also showed that the contents of some elements were higher after HVED treatment, and the largest increase was observed for calcium. All chocolates produced with treated and untreated cocoa shells had the contents of toxic elements in a range already reported in the literature. After the addition of cocoa shell in chocolate, contents of iron and cobalt were higher than reported in the literature. This presents that, generally, chocolates with added cocoa shell could be safe for human consumption but there are also some opened questions about HVED's influence on these metals that need to be answered.

Carbon Dioxide Decomposition by a Parallel-Plate Plasma Reactor: Experiments and 2-D Modelling

The applicability of high voltage electrical discharges for the decomposition of CO2 has been extensively demonstrated. In this study, a new AC parallel-plate plasma reactor is presented which was designed for this purpose. Detailed experimental characterization and simulation of this reactor were performed. Gas chromatography of the exhaust gases enabled calculation of the CO2 conversion and energy efficiency. A conversion factor approximating 25% was obtained which is higher in comparison to existing plasma sources. Optical emission spectroscopy enabled the determination of the emission intensities of atoms and molecules inside the plasma and characterization of the discharge. The Stark broadening of the Balmer hydrogen line Hβ was used for the estimation of the electron density. The obtained densities were of the order of 5 × 1014 cm−3 which indicates that the electron kinetic energy dominated the discharge. The rotational, vibrational, and excitation temperatures were determined from the vibro-rotational band of the OH radical. A 2-temperature plasma was found where the estimated electron temperatures (~18,000 K) were higher than the gas temperatures (~2000 K). Finally, a 2-D model using the fluid equations was developed for determining the main processes in the CO2 splitting. The solution to this model, using the finite element method, gave the temporal and spatial behaviors of the formed species densities, the electric potential, and the temperatures of electrons.

Study of Concentration-depth Profiles of the Titanium and Nitrogen Ions by SRIM/TRIM Simulation

In this research, the concentration-depth profiles reached by titanium and nitrogen particles, on the surface of AISI/SAE 1020 carbon steel substrates, by using of ion implantation technique, are studied. The ions are surface deposited by means of high voltage pulsed discharges and electric arc discharge under high vacuum conditions. The concentration and position distribution of the metallic and non-metallic species are obtained by simulation of the interaction of ions with the matter, stopping and ranges of ions in the matter, by the computer program transport of ions in matter. The implantation dose is calculated from the discharge data and the previously established study parameters in this work. From the simulation results, the depth profiles demonstrated that titanium and nitrogen ions may reach up to 300 Å and 600 Å and concentrations of 1.478 x 1016 ions⁄cm2 and 2.127 x 1016 ions⁄cm2, respectively. The formation of titanium microdroplets upon the surface of the substrates is identified from the micrographs obtained by the scanning electron microscopy technique; furthermore, the presence of titanium and nitrogen implanted on the surface of the substrate is verified through the elemental composition analysis by the energy dispersive spectroscopy, validating the effect of ion implantation on ferrous alloys.

Application of High Voltage Electrical Discharge Treatment to Improve Wheat Germination and Early Growth under Drought and Salinity Conditions.

The environmentally friendly, physical method of high voltage electrical discharge (HVED) was developed to improve the drought and salinity tolerance of two wheat genotypes. Unlike other plasma technologies, HVED treatment involves the discharge of electricity in water. In this study, the effect of HVED pretreatment on wheat germination and early vegetative growth under drought (0%, 15%, 20% and 30% PEG) and salinity (0, 90, 160 and 230 mM NaCl) stress conditions was investigated. HVED-exposed seeds showed altered seed surfaces and became more permeable to water uptake, resulting in higher germination percentages, germination index values, and shoot and root growth under the control and all drought and salinity concentrations. Moreover, the electrical conductivity of the water medium increased significantly, indicating HVED-induced reactions of ionization and dissociations of water molecules occurred. In addition, HVED pretreatment in the salt experiment improved the tolerance index values of the shoots and roots. The most pronounced genotypic variations occurred under the highest stress levels (30% PEG or 230 mM NaCl) and varied with the stress intensity and growth stage. The study results indicate that HVED pretreatment has the potential to improve drought and salt tolerance in wheat.

Gas-filled capillary-discharge stabilization for plasma-based accelerators by means of a laser pulse

The development of compact accelerator machines is leading towards the use of plasma-based devices that are able to sustain large acceleration gradients up to several tens of GV m−1. The main issue, in this regard, is due to the necessity to produce the plasma shot-by-shot starting from neutral gases, since its lifetime is limited to a few tens of microseconds. This puts severe limitations on its resulting uniformity, stability and reproducibility, which in turn strongly affects the quality of accelerated beams by plasmas. In this work, we describe a gas-filled discharge-capillary where the plasma generation, achieved by ionizing Hydrogen gas with a high-voltage electrical discharge, is stabilized by triggering its ignition with an external laser pulse. Results show a noticeable stabilization of the resulting plasma density along the capillary and the discharge pulse. This enables the development of very long capillaries and in turn, acceleration lengths as required, for instance, by next-generation plasma-based facilities delivering beams in the GeV-scale.

Phosphorylation of Maize Starch Enhanced with High-Voltage Electrical Discharge (HVED) Instead of Thermal Treatment.

The aim of this research was to explore the use of a high-voltage electrical treatment (HVED) as a substitute for heating during the phosphorylation of maize starch. Starch was treated with HVED, phosphorylated with Na2HPO4 or Na5P3O10 with and without thermal treatment and phosphorylated in combination with HVED prior to and after the chemical modification. When starch was phosphorylated with Na2HPO4, HVED was more efficient in catalyzing reaction (3.89 mg P/kg for 30 min HVED in relation to 0.43 mg P/kg for thermal treatment), whereas with Na5P3O10 similar P content was achieved as with thermal treatment (0.76 P/kg for 30 min HVED in relation to 0.86 mg P/kg). The order of HVED and chemical reactions did not have a marked effect on phosphorous content. In combination with Na2HPO4, HVED pre-treatment had a more pronounced effect on the solubility and water absorption, whereas post-treatment was favoured with Na5P3O10. Mean diameter was increased by all treatments, where HVED had a marked effect. Enthalpy of gelatinization ranged from 11.76 J/g for starch treated with Na5P3O10 and 10 min-HVED to 13.58 J/g for Na5P3O10 treated sample. G′ and G″ increased after both thermally and HVED enhanced phosphorylations, with a slightly more pronounced effect of the HVED.

Emerging Green Techniques for the Extraction of Antioxidants from Agri-Food By-Products as Promising Ingredients for the Food Industry.

Nowadays, the food industry is heavily involved in searching for green sources of valuable compounds, to be employed as potential food ingredients, to cater to the evolving consumers’ requirements for health-beneficial food ingredients. In this frame, agri-food by-products represent a low-cost source of natural bioactive compounds, including antioxidants. However, to effectively recover these intracellular compounds, it is necessary to reduce the mass transfer resistances represented by the cellular envelope, within which they are localized, to enhance their extractability. To this purpose, emerging extraction technologies, have been proposed, including Supercritical Fluid Extraction, Microwave-Assisted Extraction, Ultrasound-Assisted Extraction, High-Pressure Homogenization, Pulsed Electric Fields, High Voltage Electrical Discharges. These technologies demonstrated to be a sustainable alternative to conventional extraction, showing the potential to increase the extraction yield, decrease the extraction time and solvent consumption. Additionally, in green extraction processes, also the contribution of solvent selection, as well as environmental and economic aspects, represent a key factor. Therefore, this review focused on critically analyzing the main findings on the synergistic effect of low environmental impact technologies and green solvents towards the green extraction of antioxidants from food by-products, by discussing the main associated advantages and drawbacks, and the criteria of selection for process sustainability.

Inhaled Nitric Oxide Delivery Systems for Mechanically Ventilated and Nonintubated Patients: A Review.

Nitric oxide (NO) is a biologically active molecule approved for the treatment of pulmonary hypertension in newborn patients. Commercially available NO delivery systems use pressurized cylinders as the source of NO and a sensor to control the concentrations of NO and nitrogen dioxide (NO2) delivered. Cylinder-based delivery systems are safe and widely used around the world, but they are bulky, expensive, and reliant on a robust supply chain. In the past few years, novel NO generators and delivery systems have been developed to overcome these limitations. Electric NO generators produce NO from ambient air using high-voltage electrical discharge to ionize air, which leads to the formation of NO, NO2, and ozone (O3). A scavenging system is incorporated to reduce the concentration of the toxic byproducts generated in this type of system. NO can also be generated by the reduction of NO2 by ascorbic acid or released from liquid solutions or solid nanoparticles. The development of easy-to-use, safe, and portable NO delivery systems may enable the delivery of NO in the out-patient setting or at home. Furthermore, non-cylinder-based NO generators reduce the cost of NO production and storage and may therefore make NO delivery feasible in low-resource settings. Here we review commercially available systems that can generate and administer inhalable NO.