Continuous Pulsed Electric Field Research Articles

Continuous pulsed electric field processing for intensification of aqueous extraction of protein from fresh green seaweed Ulva sp. biomass

The green marine macroalgae Ulva sp. can reach a high protein content and a high composition of essential amino acids. In this study, we have developed a novel device and investigated the parameters for a continuous Pulsed Electric Field (PEF) process, coupled with enzyme treatment followed by a spray drying, to facilitate the aqueous fractionation of Ulva protein. The process demonstrated 8.79 ± 0.58 (% w/w) protein extraction yield. Furthermore, the aqueous fractionation of protein exhibited a substantial 41.45% essential amino acid content and a branched amino acids composition of 17.58%. Additionally, it displayed an in vitro relative digestibility of 87.4 ± 1.36% compared to soy protein, along with a water holding capacity of 7.15 ± 0.17 g water/g sample and an oil holding capacity of 1.76 ± 0.11 g oil/g sample. These findings suggest that employing a continuous PEF process in conjunction with enzyme-induced cell wall degradation could position green marine macroalgae as an important potential source for food protein ingredients.

Effect of pulsed electric field processing on microbial and enzyme inactivation in blended plant-based milk alternatives: A case study on a microbial challenge test for a non-presterilized oat-based beverage enriched with pea protein

Microbial and enzyme inactivation by pulsed electric field (PEF) treatment was assessed in a blended plant-based milk alternative (PBMA) containing oats and pea protein without the application of presterilization. This was conducted to investigate a novel approach that permits PEF process validation for PBMA containing heat-labile components (protein and starch). Continuous PEF processing at moderate field strengths (9–10 kV/cm) combined with mild preheating (30–45 °C) for 25 s was applied over a range of specific energy inputs (77–245 kJ/L). Selective plating permitted bacterial enumeration of inoculated surrogate organisms, despite the presence of natural microbial contaminants in the non-presterilized product. A minimum 5-log reduction of inoculated surrogates Escherichia coli and Listeria innocua alongside native microbiota was identified after preheating to 35–45 °C followed by PEF at 192–215 kJ/L. α-amylase activity was reduced by up to 89% during a similar PEF treatment (205 kJ/L, 40 °C preheating). Overall, continuous PEF combined with mild preheating temperature was shown to achieve microbial inactivation in the pea protein enriched PBMA in compliance with current food safety regulations. Industrial relevancePresterilization is typically applied prior to conducting microbial challenge testing on food products to validate novel pasteurization treatments according to current regulatory requirements that a minimum 5-log reduction of relevant inoculated food pathogens must be achievable. However, for a variety of blended PBMA containing heat-labile proteins, presterilization is not advisable as the occurrence of irreversible changes in the product quality linked to protein coagulation and phase separation will affect the inactivation efficacy during subsequent microbial challenge testing. Hence, an alternative approach is presented utilizing a non-presterilized PBMA and thorough microbiological analysis, combining non-selective and selective plating techniques. This allows an identification of PEF treatment parameter with a minimum 5-log reduction of inoculated surrogate organisms alongside naturally present microbial contaminants. This may serve as a valuable guideline for stakeholders in the food industry when addressing the efficacy of novel preservation treatments such as PEF in PBMA products with similar heat-induced product stability challenges.

Time-dependent model of temperature distribution in continuous flow pulsed electric field treatment chambers

A key component of a continuous flow pulsed electric field (PEF) system is the treatment chamber, where the product is exposed to electric pulses. Determination of the temperature distribution in the chamber during PEF treatment is important since high local increases in temperatures can affect the quality of the product. Coupled simulations of electric field, fluid flow, and heating in the existing literature do not model each individual electric pulse, but rather employ a “duty cycle” approach, which does not account for transient variations in treatment intensity and temperature changes in the medium. We present a time-dependent approach to modelling PEF treatment in continuous flow treatment chambers, which can model each pulse separately, and thus enables a more accurate study of temporal and spatial distributions of electric field and temperature. The model has been validated on laboratory scale treatment chambers of parallel plate or colinear design and using realistic protocols. Industrial relevance textThe paper is relevant to all pulsed electric field (PEF) applications either on laboratory or industrial scale that implement a continuous flow treatment chamber. It presents an improved modelling approach which allows for an analysis of the electrical current, electric field, and temperature distribution in the chamber during, at the end, and in between application of electrical pulses. The model can be used to predict the peak temperature at the end of each pulse in the hot spots, which if large enough could potentially lead to thermal damage of the product or in extreme cases even potential local boiling of the medium, resulting not only in degradation of the treated product, but also in accelerated electrode fouling, oxidation, and dissolution (etching), as well as arcing. This would not only affect the quality of the treated product but would also affect the wear and lifetime of electrodes/chambers, and of the pulse generator. The model can also be used to avoid expensive trial-and-error optimization of the PEF protocols and chamber geometries in situ.

Pilot Scale Continuous Pulsed Electric Fields Treatments for Vinification and Stabilization of Arinto and Moscatel Graúdo (Vitis vinifera L.) White Grape Varieties: Effects on Sensory and Physico-Chemical Quality of Wines

Pulsed electric field (PEF) processing of white grapes (Arinto, Moscatel Graúdo also known as Moscatel de Setúbal) before pressing for must extraction (1.2 and 1.6 kV/cm) and before bottling for finished wine physical stabilization (10 kV/cm) was implemented in a pilot-scale winery to produce about 540 L of wine for each variety. PEF was applied at these two different stages of wine production, and its effects on the sensory and physico-chemical quality of the wines were investigated. The sensory triangle tests revealed no significant change in both wine varieties’ colour, odour, and taste with PEF extraction and PEF stabilization treatments. However, for colour coordinates assessed with a spectrophotometer, a significant increase in CIE b* colour coordinate was registered for PEF-extracted Arinto and Moscatel wine samples, showing a development of a more intense yellow colour. Concerning physico-chemical quality parameters, the PEF extraction increased both wine varieties’ turbidity and pH, although total acidity was not affected. The total phenols also increased in Arinto with extraction. The second PEF treatment applied for wine stabilization did not affect any of the quality parameters, except total phenols, which decreased in Moscatel wine. The results encourage the application of PEF in the wineries at different stages of vinification of white wine grape varieties.

Defining winery processing conditions for the decontamination of must and wine spoilage microbiota by Pulsed Electric Fields (PEF)

This study investigated the PEF-resistance of Saccharomyces bayanus, Brettanomyces bruxellensis, Lactobacillus plantarum, and Oenococus oeni in must or wine under continuous PEF processing. Results showed the capacity of PEF to achieve 3.0-log10-cycles (CFU/mL) of inactivation of all the microorganisms under moderate conditions (< 155 kJ/kg). Developed tertiary models accurately predicted the effect of PEF parameters on microbial inactivation, and Monte Carlo simulation considered the variability of factors and the maximum assumable microbial load in the final treated product. Results showed that PEF-treatments at 15 kV/cm and 129 or 153 kJ/kg would ensure the adequate decontamination (< 10 CFU/mL) of spoilage microorganism in must or wine, respectively. Industrial relevancePEF technology has been shown to achieve adequate levels of microbial inactivation (3-log10) in must and wine under industrial applicable processing parameters, making it a suitable alternative to SO2 or sterilizing filtration for microbial control in winemaking. Reductions of 3-log10 CFU/mL of must and wine microbiota were found by continuous flow PEF-processing at 15 to 25 kV/cm and 175 to 148 kJ/kg, parameters applicable at industrial scale at 1 ton/h.

Extracting Water-Soluble Proteins from the Red Macroalgae Gracilaria sp. with Pulsed Electric Field in a Continuous Process

Marine macroalgae are an emerging sustainable source of protein; however, protein extraction from macroalgae is challenging. In this work we report a novel, screw-press-based device for continuous high-voltage pulsed-electric-field (PEF) processing of fresh biomass to extract water-soluble protein from the red seaweed Gracilaria sp. The water extracts from the PEF-treated biomass showed higher protein yield (37.82 ± 7.96 to 47.56 ± 10.54 mg/g initial dry weight (DW) of biomass, depending on PEF conditions) compared to extracts without PEF (33.82 ± 6.01 mg/g initial DW of biomass). PEF followed by aqueous extraction removed 69.11% of the ash from the Gracilaria sp. biomass. The in vitro digestibility of the proteins in the water-soluble extract from the PEF process was 70% compared to that of casein, but it was only 25% for the juice protein extracted with a screw press alone. The energy consumption for PEF was 2.94 ± 0.91 kJ/(kg fresh weight (FW)) – 4.06 ± 0.48 kJ/kgFW, depending on the applied voltage. This study is the first report of processing Gracilaria sp. biomass using a continuous PEF system and successfully demonstrates the protein extraction with relatively lower energy inputs.

Effect of Pulsed Electric Field on the Electrodialysis Performance of Phosphate-Containing Solutions.

A comparative analysis of mass transfer characteristics and energy consumption was carried out for the electrodialysis recovery of PV from of NaH2PO4 solutions and multicomponent (0.045 M NaxH(3-x)PO4, 0.02 M KCl, 0.045 M KOH, 0.028 M CaCl2, and 0.012 M MgCl2, pH 6.0 ± 0.1) solution in conventional continuous current (CC) and pulsed electric field (PEF) modes. The advantages of using PEF in comparison with CC mode are shown to increase the current efficiency and reduce energy consumption, as well as reduce scaling on heterogeneous anion-exchange membranes. It has been shown that PEF contributes to the suppression of the "acid dissociation" phenomenon, which is specific for anion-exchange membranes in phosphate-containing solutions. Pulse and pause lapse 0.1 s-0.1 s and duty cycle 1/2 were found to be optimal among the studied PEF parameters.

Continuous pulsed electric field pilot plant for olive oil extraction process

The olive oil extraction industry often uses unit-constructed processing lines lacking in the necessary efficiency and sustainability. The development of efficient processing lines is seen as crucial in obtaining higher product quality and extraction yields. In recent years, numerous researchers and companies have explored the possibilities of assistance from pulsed electric fields (PEF) technology as a mean of reducing processing time and increasing extraction yields from different food crops. The current article shows the application of PEF technology in olive oil extraction, and specifically it researches the results from application of PEF technology in a pilot plant of industrial-layout olive oil extraction process. The experimental methodology involves construction of a plant meeting specific functional and cost criteria, capable of delivering unipolar electric pulses with amplitude <10 kV, current <200 A and 3 kW maximum average power. The analyses then focalize on the assessment of the results from PEF assistance on oil extraction, particularly in terms of extractability from crop and enhancement of bioactive substances content. The proposed PEF unit was found to be easy to install within existing plants, flexible in control and capable of continuous operation. Operating at different pulse and power levels, the plant results in increased process efficiency and content of desirable substances.

Phenolic and colour characteristics of must and wine obtained from red grapes treated by pulsed electric fields. Efficacy of PEF to reduce maceration time in elaboration of red wines

Pulsed electric fields effect was studied on the physico-chemical and general phenolic composition as colour characteristics and stilbene content in must and wine. For this purpose, a continuous pulsed electric fields equipment was used to treat three red grape varieties of DOCa Rioja. Graciano, Tempranillo and Grenache wines from these grapes were elaborated with different maceration times, 2 days in the untreated sample (control) and the PEF-treated sample (PEF), and normal maceration time in another untreated sample (control-NM). Parameters as colour intensity, anthocyanin content, total polyphenol index and tannin content showed no differences between the PEF sample with 2 days of maceration and the control-NM sample, except in the case of Tempranillo wines. Total stilbenes, trans-resveratrol and trans-piceid of Graciano wines elaborated from PEF samples showed a higher concentration than the control wines. Alternatively, PEF wines and control-NM wines showed no differences between them. Tempranillo variety wines presented no differences between the three types of samples. In the Grenache variety, only trans-piceid levels showed differences between control and PEF wines. Moreover, relationship between must and wine characteristics was evaluated and compared between different samples. The trend lines obtained for the CI, TPI and AC parameters for samples of Graciano, Tempranillo and Garnacha indicate that the initial content of compounds extracted significantly affected the days of maceration necessary to obtain the appropriate wine. The results obtained increase the knowledge of pulsed electric fields as a technology available for use in the winery to elaborate red wines with reduced maceration time.

Microbial safety and shelf‐life of pulsed electric field processed nutritious juices and their potential for commercial production

Pulsed electric field (PEF) processing criteria which could achieve 5 or more log reduction of foodborne pathogens were obtained to get regulatory approval for the commercial production of three unique nutritious juices. Juice samples inoculated with Escherichia coli O157:H7 and Salmonella Typhimurium were processed in a continuous PEF process system. Among 18 tested conditions, three PEF treatments achieved an over 5 log reduction in populations of these pathogens. There was no recovery or regrowth of the pathogens in treated juices during storage at 4, 10, and 22°C. After 24 week-storage, population levels of native microorganisms in treated juices were the same or lower than those of the control samples at Day 0, except for those in apple-honey juice stored at 22°C. PEF processing had no significant effects on °Brix, pH, color, and vitamin C retention. This study provides an important step for the commercialization of PEF application. Novelty impact statement This study was specially designed for the project sponsored by a commercial juice producer. New and unique neutrinos juices were used to establish PEF processing criteria to achieve a 5 log or greater reduction of foodborne pathogens so that all data from this study can be used for regulatory approval and optimum processing conditions obtained from this study will be used for the commercial production of these juice products. This study also provides valuable information to the juice producers with similar nutritious juice products.

Simulation Study of Coaxial Treatment Chambers for PEF Pasteurization: A Critical Review

A pulsed electric field (PEF) produces pasteurized liquid foods with fresh and nutritional properties. The treatment chamber is a crucial part of the PEF processing system where a high voltage is applied, producing an electric field to treat the liquid foods. The proper construction of the treatment chamber regulates the distribution of the electrical field inside the treatment zone. Mixing of liquid inside the treatment zone is an effective tool to overcome this heterogeneous effect. The coaxial treatment chamber offers a heterogeneous electric field and temperature distribution inside the treatment zone. A helical insulator inside the coaxial treatment chamber provides a mixing effect. In this research, a numerical simulation was done to measure the electric field in different geometries of treatment chambers at different flow rates. The simulation aimed to optimize the new coaxial treatment chamber design. The modelling findings showed homogeneous electrical field strength in the helical treatment chamber. This study provides new insights for industrial-scale setup using multiple helical chambers in a continuous flow PEF treatment.

Pulsed electric field treatment of Lacticaseibacillus rhamnosus and Lacticaseibacillus paracasei, bacteria with probiotic potential

Lactic acid bacteria play an important role in functional food and fermentation products for human and animal nutrition, as probiotics, paraprobiotics, postbiotics or high-lactic acid-producing strains in biorefineries. Pulsed electric field (PEF) treatment is gaining recognition in the food industry, but little is known about the effects of PEF treatment on the probiotic characteristics of lactic acid (LA) bacteria or its application for the production of paraprobiotics and postbiotics. Thus, we studied the inactivation kinetics and permeabilization of Lacticaseibacillus rhamnosus and Lacticaseibacillus paracasei as high LA-producing strains with probiotic characteristics by batch and continuous PEF treatment.Significant linear correlations between the logN reduction and permeabilization of the studied bacteria and specific energy input and current were observed during PEF treatment. Sublethal PEF treatment (5 kV/cm, 8 × 1 ms, 1 Hz) induced 10% higher LA production in L. rhamnosus, as well as the release of proteins from both bacteria. Sublethal PEF treatment did not change the susceptibility to specific antibiotics in L. rhamnosus, while L. paracasei showed some decrease in susceptibility to antibiotics. The results obtained are valuable for PEF treatment of functional food with probiotics and the production of paraprobiotics and postbiotics to improve food safety and functionality.

Enhanced solute diffusion to promote shear-type reverse transformation recovery in metastable austenitic stainless steel

The martensite reverse transformation behavior and the effect of microstructure differences on mechanical properties were investigated in metastable austenitic stainless steel. During continuous heating, whether annealing or pulsed electric field treatment, the deformation-induced martensite transforms to austenite by diffusionless shear reversion. In subsequent isothermal holding, the samples treated by pulsed electric treated accomplish the reverse transformation from martensite to austenite, and forming the equiaxed, defect-free austenite grains, but the martensitic reversion in annealed samples is incomplete, consisting of the diffusion-type austenite, lath-type austenite and dislocation cells. The difference in microstructure is caused by atomic diffusion in essence. Under a pulsed electric field, the atom receives an electric force that reduces the activation energy required for diffusion. Therefore, the atom diffusion is promoted, which accelerates the dislocations climbing and subgrain boundaries coalescence and then promoting the schedule of recrystallization. As a result, the difference in microstructure has a significant effect on the mechanical properties, i.e., the annealed cold-rolled austenitic stainless steels have higher strength with poor ductility, yet the pulsed steels present an excellent ductility. The reason for the difference in mechanical properties is likely to the phase transformation-induced plasticity responses.

Pulsed electric field of goat milk: Impact on Escherichia coli ATCC 8739 and vitamin constituents

AbstractThere is a dire need to produce shelf‐stable and safe goat milk with minimal effects on its nutritive quality. In this study, raw goat milk was processed with a continuous pulsed electric field (PEF) system, at various electric field strength (EFS: 20, 25, 30, 35, and 40 kV/cm) and processing time (5, 7, 10, and 13 μs). The maximum log reduction of Escherichia coli was 3.87 log CFU/ml, achieved at 40 kV/cm for 13 μs. Weibull and Peleg models were better fitted to the inactivation kinetics of E.coli ATCC 8739 as a function of processing time and EFS, respectively. The mean concentration of vitamin A (as β‐carotene) and B‐group vitamins (thiamine, riboflavin, and niacin) were nonsignificantly (p &gt; .05) decreased compared to the unprocessed sample. Since the inactivation level did not reach the minimum log reduction recommended by USFDA, PEF is recommended as a complementary method to mild thermal pasteurization.Practical ApplicationsPEF processing has gained recognition in food processing through halting an adverse issue of thermal processing. Although PEF is drifting toward industrial practice, it is essential to verify the efficiency of PEF in a complex matrix like goat milk to assure PEF can be utilized for industrial use. The results of this study show that the PEF can be recommended as a complementary method to mild thermal pasteurization as a hurdle processing technique to ensure the safety and nutritive qualities of goat milk at the industry level.

Impact of Pulsed Electric Field on Glycerin Sedimentation from Biodiesel Production Process

This research aims to study the impact of continuous pulsed electric field (PEF) on glycerin separation from Transesterification process. Transesterification process of biodiesel production using 100 ml vegetable oils with alcohol of 1:5 molar ratio together with potassium hydroxide (KOH) as catalyst 1 wt.% for the reaction. The designed glass tube reaction chamber is 250 ml contained with coaxial cylindrical electrodes. The applied voltage to an electrode was at 1 kV and frequency of 1 kHz with pulse duration of 500 μs and also 4 kHz with pulse duration of 125 μs. The results showed that the glycerin volume from transesterification process has rapidly sedimented with pulsed electric field method. It is much faster than using conventional gravity method. The sedimentation rate increases rapidly with an increasing in frequency of the applied voltage. The highest volume of glycerin sedimentation of 10.2 ml is by using pulsed electric field at 1 kV and 4 kHz.

Development of a Continuous Pulsed Electric Field (PEF) Vortex-Flow Chamber for Improved Treatment Homogeneity Based on Hydrodynamic Optimization.

Pulsed electric fields (PEF) treatment is an effective process for preservation of liquid products in food and biotechnology at reduced temperatures, by causing electroporation. It may contribute to increase retention of heat-labile constituents with similar or enhanced levels of microbial inactivation, compared to thermal processes. However, especially continuous PEF treatments suffer from inhomogeneous treatment conditions. Typically, electric field intensities are highest at the inner wall of the chamber, where the flow velocity of the treated product is lowest. Therefore, inhomogeneities of the electric field within the treatment chamber and associated inhomogeneous temperature fields emerge. For this reason, a specific treatment chamber was designed to obtain more homogeneous flow properties inside the treatment chamber and to reduce local temperature peaks, therefore increasing treatment homogeneity. This was accomplished by a divided inlet into the chamber, consequently generating a swirling flow (vortex). The influence of inlet angles on treatment homogeneity was studied (final values: radial angle α = 61°; axial angle β = 98°), using computational fluid dynamics (CFD). For the final design, the vorticity, i.e., the intensity of the fluid rotation, was the lowest of the investigated values in the first treatment zone (1002.55 1/s), but could be maintained for the longest distance, therefore providing an increased mixing and most homogeneous treatment conditions. The new design was experimentally compared to a conventional co-linear setup, taking into account inactivation efficacy of Microbacterium lacticum as well as retention of heat-sensitive alkaline phosphatase (ALP). Results showed an increase in M. lacticum inactivation (maximum Δlog of 1.8 at pH 7 and 1.1 at pH 4) by the vortex configuration and more homogeneous treatment conditions, as visible by the simulated temperature fields. Therefore, the new setup can contribute to optimize PEF treatment conditions and to further extend PEF applications to currently challenging products.

Influence of Pulsed Electric Fields processing at high-intensity electric field strength on the relationship between anthocyanins composition and colour intensity of Merlot (Vitis vinifera L.) musts during cold maceration

Abstract Merlot grapes have high proportion of anthocyanins protected inside cell vacuoles but the thick skins limit their extractability. This study investigated the effect of a continuous Pulsed Electric Fields (PEF at 500 kg/h) system operated at high-intensity electric field strengths (>30 kV/cm) combined with energy inputs ranging from 4.7 to 49.4 kJ/L on anthocyanins extraction and colour intensity of Merlot musts during a 4-day cold maceration. Considerable amount of anthocyanins with different chemical features was extracted instantaneously due to PEF treatment at high-intensity electric field strength, in which the amount was higher than those extracted from non PEF-treated Merlot followed by 4 days maceration. During maceration, malvidin derivatives were the most significant anthocyanins contributing (r > 0.71, p Industrial relevance text Previous PEF studies mainly investigated the effect of low-intensity electric field strength ( 30 kV/cm) using Marx generator for the first time in the literature. Marx generator has a tendency to produce high-intensity electric field strength, up to 80 kV/cm, but the impact on plant materials intended for food application are not well studied. In this study, Merlot grapes were continuously treated with PEF at high-intensity electric field strength at a flow rate of 500 kg/h while many previous studies conducted trial at approximately 100–200 kg/h in conjunction with low-intensity electric field strength ( 200 kg/h) at the commercial scale. In this study, we have successfully showed that high-intensity electric field strengths (33.1 and 41.5 kV/cm) of PEF were efficient (i.e. instantaneous extraction) in extracting all types of anthocyanins with different chemical features from the thick-grape skins of Merlot. Therefore, grape juice with more elaborated anthocyanin composition and intense colour was produced at a large scale immediately after PEF. The extracted anthocyanins were found to be stable over time after PEF treatment in which the issues on anthocyanin stability and colour development have never been considered in many previous studies, but are important quality aspects that beverage industry desired.

Challenges and limitations for the decontamination of high solids protein solutions at neutral pH using pulsed electric fields

Pulsed electric fields (PEF) can be used to pasteurize aqueous liquid foods at reduced temperatures to provide increased product quality, depending on the individual product to be treated. Thus, the continuous decontamination of high solids (10–25% dm) protein solutions by PEF at neutral pH was investigated in detail in this study, evaluating different processing strategies. Resultsindicate that, independent of the individual matrix used (10, 18, 25% whey protein; 10% skim milk concentrate, skim milk), inactivation levels obtained using a co-linear treatment chamber were in the same range and seemingly only based on heat-induced mechanisms. The use of further alternative treatment chamber configurations did also not positively influence the effectiveness of continuous PEF pasteurization. This confirms the protective effect of proteins considering inactivation of microorganisms by PEF and the decreased efficiency of the treatment for foods at neutral pH levels.

Design and Optimization of a Microchip Operating at Low-Voltage Pulsed Electric Field for Juice Sterilization

Microchip has been widely used in the biochemical field, but it is rarely applied in the food area. In this paper, an optimal microelectrode model was obtained via the improved evolutionary structural optimization (ESO) method, the effect of topological parameters on the sterilization efficiency was clarified, and the optimized microchip was applied to the sterilization of blueberry juice to verify its feasibility. The analysis of finite element method (FEM) results showed that planar comb teeth (PCT) form, quadrilateral electrode structure with 100-μm electrode spacing, was the ideal model for the microchip. On the basis of the optimal electrode model, a continuous low-voltage pulsed electric field (LPEF) experimental platform was built. Under 400 V and 0.2-ms conditions, LPEF processing better preserved vitamin C, anthocyanin, total phenolics content, and color parameters while reducing microbial counts in blueberry juice significantly. During 30 days of storage at 4 °C, LPEF-treated juices had more vitamin C, anthocyanin content, and brighter color under the premise of ensuring microbiological safety, compared with high temperature short time (HTST) and pulsed electric field (PEF)-treated juices. This study provides theoretical and technological support for the widespread use of LPEF technology in the application of a non-thermal processing technique for food.

Continuous nanosecond pulsed electric field treatments foster the upstream performance of Chlorella vulgaris-based biorefinery concepts

Nanosecond pulsed electric field treatment (nsPEF) is an innovative, technology-driven, and resource-efficient approach to foster the upstream performance of microalgae-based biorefinery concepts to transform microalgae into economic more viable raw materials for the biobased industry. A processing window applying three treatments of 100 ns, 5 Hz, and 10 kV cm−1 to industrially relevant phototrophic Chlorella vulgaris in the early exponential growth phase significantly increased biomass yields by up to 17.53 ± 10.46% (p = 3.18 × 10−5). Treatments had limited effects on the carbon and pigment contents, but the protein content was decreased. The longest possible pulse width (100 ns) resulted in the highest biomass yield indicating underlying working mechanisms of enhanced cell proliferation based on intracellular and plasma membrane-related effects. The applicability to eukaryotes and prokaryotes, such as C. vulgaris and cyanobacteria highlights the possible impacts of nsPEF across multiple domains of the biobased industry relying on single-cell-based value-chains.