Pulsed Electric Field Treatment Conditions Research Articles

Effect of pulsed electric field processing on the quality characteristics and enzyme activity of tender coconut water.

Tender coconut water (TCW) is a natural drink rich in natural electrolytes, minerals, salts and sugars; it has good health benefits. But, its shelf-life is very limited because of the active nature of enzymes present in it when exposed to air. Therefore, the processing of TCW is necessary to inactivate the enzymes. So, this study aims to observe the effect of various process parameters of pulsed electric field (PEF) on the quality parameters of TCW. For the treatment of TCW with PEF, a full-factorial design of experiments was followed with process parameters such as three levels of electric field intensity (8, 12, and 16 kV/cm), two levels of pulse width (PW) (50 and 70 μs), and six levels of the number of pulses (2000 to 12,000 pulses) were considered at a constant pulse OFF time of 75 ms. PEF treatment did not significantly change pH, total soluble solids, and viscosity. However, it significantly affected vitamin C, colour, and total and reducing sugars. PEF treatment significantly enhanced the total phenolic content and antioxidant activity by 23.17% and 42.49%, respectively. At the same time, significant inactivation of polyphenol oxidase (100%) and peroxidase (60.2%) was observed at PEF treatment conditions of 16 kV/cm, 70 μs PW, and 12,000 pulses. Moreover, no significant change in the sensory acceptability of PEF-treated TCW (16 kV/cm, 70 μs PW, 12,000 pulses) when compared to the untreated/fresh TCW, which is a promising sign.

Effect of Pulsed Electric Fields on the Shelf Stability and Sensory Acceptability of Osmotically Dehydrated Spinach: A Mathematical Modeling Approach.

This study focused on the osmotic dehydration (OD) of ready-to-eat spinach leaves combined with the pulsed electric field (PEF) pre-treatment. Untreated and PEF-treated (0.6 kV/cm, 0-200 pulses) spinach leaves were osmotically dehydrated at room temperature for up to 120 min. The application of PEF (0.6 kV/20 pulses) prior to OD (60% glycerol, 25 °C, 60 min) lowered water activity (aw = 0.891) while achieving satisfactory product acceptability (total sensory hedonic scoring of 8). During the storage of the product (at 4, 8, 12, and 20 °C for up to 30 d), a significant reduction in total microbial count evolution was observed (9.7 logCFU/g for the untreated samples vs. 5.1 logCFU/g for the PEF-OD-treated samples after 13 d of storage at 4 °C). The selection of these PEF and OD treatment conditions enabled the extension of the product shelf life by up to 33 d under chilled storage. Osmotically treated spinach could find application in ready-to-eat salad products with an extended shelf life, which is currently not possible due to the high perishability of the specific plant tissue.

Biological autoluminescence enables effective monitoring of yeast cell electroporation.

The application of pulsed electric fields (PEFs) is becoming a promising tool for application in biotechnology, and the food industry. However, real-time monitoring of the efficiency of PEF treatment conditions is challenging, especially at the industrial scale and in continuous production conditions. To overcome this challenge, we have developed a straightforward setup capable of real-time detection of yeast biological autoluminescence (BAL) during pulsing. Saccharomyces cerevisiae culture was exposed to 8 pulses of 100 µs width with electric field strength magnitude 2-7kV cm-1. To assess the sensitivity of our method in detecting yeast electroporation, we conducted a comparison with established methods including impedance measurements, propidium iodide uptake, cell growth assay, and fluorescence microscopy. Our results demonstrate that yeast electroporation can be instantaneously monitored during pulsing, making it highly suitable for industrial applications. Furthermore, the simplicity of our setup facilitates its integration into continuous liquid flow systems. Additionally, we have established quantitative indicators based on a thorough statistical analysis of the data that can be implemented through a dedicated machine interface, providing efficiency indicators for analysis.

Impact of pulsed electric field treatment on barley germination for malting

The malting process takes one week to steep, germinate, and kiln barley to make malt. Making quality malt is critically important to achieve the desired attributes of the finished beer, and the process is time-intensive and costly. Malt quality is assessed by indicators including β-glucan quantity, α-amylase activity, Free Amino Nitrogen (FAN) content, and overall extract concentration in the finished malt. Here, we report Pulsed Electric Field (PEF) treatment of barley to accelerate malt production. A small-scale trial of 250 g to 1.00 kg barley, was evaluated for germination at two PEF treatment conditions, generically referred to as “low” and “high”, that resulted in increased barley rootlet length during germination of 1.3 mm longer than was observed for the control. Large-scale trials of 1.00 kg–3.00 kg barley, resulted in an increase in germination rate and a decrease of β-glucan concentration in the PEF treated barley. Micromalted barley using PEF parameters of 1.0 kV/cm and 15.0 kJ/kg displayed a reduction in β-glucan concentration by 38%, and increase in malt extract by 1.5%, FAN by 6.2%, and α-amylase by 8.4%, supporting the hypothesis that PEF treated barley generates more and better malt, leading to greater efficiency in the beer making process.

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.

Pulsed Electric Field: Fundamentals and Effects on the Structural and Techno-Functional Properties of Dairy and Plant Proteins.

Dairy and plant-based proteins are widely utilized in various food applications. Several techniques have been employed to improve the techno-functional properties of these proteins. Among them, pulsed electric field (PEF) technology has recently attracted considerable attention as a green technology to enhance the functional properties of food proteins. In this review, we briefly explain the fundamentals of PEF devices, their components, and pulse generation and discuss the impacts of PEF treatment on the structure of dairy and plant proteins. In addition, we cover the PEF-induced changes in the techno-functional properties of proteins (including solubility, gelling, emulsifying, and foaming properties). In this work, we also discuss the main challenges and the possible future trends of PEF applications in the food proteins industry. PEF treatments at high strengths could change the structure of proteins. The PEF treatment conditions markedly affect the treatment results with respect to proteins’ structure and techno-functional properties. Moreover, increasing the electric field strength could enhance the emulsifying properties of proteins and protein-polysaccharide complexes. However, more research and academia–industry collaboration are recommended to build highly effective PEF devices with controlled processing conditions.

Improving the Extraction of Catechins of Green Tea (Camellia sinensis) by Subcritical Water Extraction (SWE) Combined with Pulsed Electric Field (PEF) or Intense Pulsed Light (IPL) Pretreatment.

The aim of this study was to find the optimum condition of pulsed electric field (PEF) and intense pulsed light (IPL) for the enhancement of subcritical water extraction (SWE), which is an eco-friendly extraction method, for extracting tea catechins from green tea leaves (Camellia sinensis). The leaves were treated with PEF under conditions of electric field strength (1, 2 and 3 kV/cm) during 60 s. Moreover, IPL was applied at various voltages (800, 1000, and 1200 V) for 60 s. The SWE was performed for 5 min at varying temperatures (110, 130, 150, 170, and 190 °C). The maximum yield of total catechin was 44.35 ± 2.00 mg/g dry green tea leaves at PEF treatment conditions of 2 kV/cm during 60 s, as well as the SWE temperature of 130 °C. In the case of IPL treatment, the largest amount of total catechin was 48.06 ± 5.03 mg/g dry green tea leaves at 800 V during 60 s when the extraction temperature was 130 °C. The total catechin content was increased by 15.43% for PEF and 25.09% for IPL compared to the value of untreated leaves. This study verified that PEF and IPL had a positive effect on the enhancement of tea catechins extraction from green tea leaves using SWE.

Pulsed electric fields‐ and ultrasound‐assisted green extraction of valuable compounds from Origanum vulgare L. and Thymus serpyllum L.

SummaryThis work compared the effects of pulsed electric fields (PEF) and ultrasound (US) technologies on the extent of cell disintegration of two Mediterranean herb tissues (Origanum vulgare L., Thymus serpyllum L.), as well as on the extractability of phenolic compounds during the subsequent hydroalcoholic extraction (0%–50% ethanol in water, v/v) for up to 4 h. The rate of phenolic compounds extraction decreased with time and was predicted rather satisfactorily (R2 = 0.898–0.989) by the Peleg’s model. The application of either PEF or US treatment prior to solid–liquid extraction (SLE) has the potential to reduce duration and concentration of ethanol to achieve the same recovery yield of phenolic compounds. Under optimised PEF (3 kV cm−1, 10 kJ kg−1) and US (400 W, 20 min) treatment conditions, the extracts obtained from either PEF or US pretreated herb samples showed higher total phenolic yield (36% on average) and antioxidant activity (FRAP) (36% on average) as compared to the control extraction, especially when 25% ethanol was used as a solvent. GC/MS analyses revealed no evidence of degradation of individual phenolics due to either PEF or US application.

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.

Reversibility of membrane permeabilization upon pulsed electric field treatment in Lactobacillus plantarum WCFS1

Pulsed electric field (PEF) treatment, or electroporation, can be used to load molecules into cells. The permeabilizing effect of the PEF treatment on the cellular membrane can be either reversible or irreversible depending on the severity of the PEF treatment conditions. The influence of PEF on the reversibility of membrane permeabilization in Lactobacillus plantarum WCFS1 by two different fluorescent staining methods was investigated in this study. Whereas staining with propidium iodide (PI) before and after PEF treatment indicated small reversible permeabilized fractions of maximum 14%, the use of a double staining method with PI and SYTOX Green suggested larger reversible permeabilized fractions up to 40% of the population. This difference shows that the choice for a fluorescent staining method affects the conclusions drawn regarding reversibility of membrane permeabilization. Additionally, the effect of PEF treatment conditions on membrane integrity was compared, indicating a relation between critical electric field strength, cell size and membrane permeabilization. Overall this study showed the possibilities and limitations of fluorescent membrane integrity staining methods for PEF studies.

Intracellular antioxidant activity and apoptosis inhibition capacity of PEF-treated KDHCH in HepG2 cells.

The effect of pulsed electric field (PEF) treatment on the intracellular antioxidant and apoptotic activity of the peptide Lys-Asp-His-Cys-His (KDHCH) was examined using model HepG2 cells. First, PEF treatment conditions specific for the antioxidant peptide were optimized, and it was found that PEF treatment could enhance DPPH, ABTS and hydroxyl radical scavenging capacity of KDHCH. Second, KDHCH subjected to PEF treatment at 1800 Hz and 15 kV/cm was investigated using various intracellular antioxidant assays. PEF treatment decreased the EC50 value and increased the protective ability of oxidative stress inhibition and reactive oxygen species (ROS) scavenging activity of KDHCH. Furthermore, catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and glutathione reductase (GR) activities of KDHCH-pre-treated HepG2 cells increased significantly compared with those of the H2O2 damaged group, whereas lactate dehydrogenase (LDH) and malonaldehyde (MDA) content were decreased. PEF-treated KDHCH exhibited an increased capacity to maintain the stability of mitochondrial membrane potential (MMP) and reduced the level of caspase-3. These results indicate that PEF treatment can enhance the intracellular antioxidant activity of KDHCH, which can inhibit the effect of H2O2 oxidation on HepG2 cells by inhibiting the accumulation of intracellular ROS, regulating antioxidant related enzymes, and blocking the apoptotic mitochondrial pathways activated by ROS.

Understanding the effect of Pulsed Electric Fields on multilayered solid plant foods: Bunching onions (Allium fistulosum) as a model system

While it is well known that the nature of the applied electric field and the heterogeneity of the tissue can influence the impact of PEF treatment on the plant tissues found in plant-based foods, few studies have investigated the influence of PEF on plant structures that are made up of multiple structurally similar organs. The aim of this study was to understand the effect of pulsed electric fields (PEF), at different electric field strengths (0, 0.3, 0.7 and 1.2 kV/cm) and specific energy (7, 21 and 52 kJ/kg), on a multilayered plant material, with bunching onion bulb tissues being used as a model system. The present study found that carbohydrates leakage was an appropriate index to assess PEF induced damage and that plasmolysis of epidermal cells was a good indicator of plasma membrane integrity after PEF. In addition, electric field strength had a greater impact on the cell integrity than specific energy applied. While other studies have shown that different cell types have different sensitivities to PEF, using plasmolysis as an indicator of cell damage, this study clearly showed that the same PEF treatment conditions had a greater effect on the epidermal cells of the outer scales compared to the inner scales. Hence, while different plant cell types vary in their sensitivities to PEF the spatial location of the same cell type within a complex plant material made up of multiple similar organs, i.e. an onion bulb, can also influence how cells respond to the PEF treatment. Despite PEF induced disruption at the cellular level being detected by carbohydrate leakage, the epidermal cell plasmolysis test and by cryo-scanning electromicroscopy (cryo-SEM), no gross structural changes at the organ level were observed using cryo-SEM or fluorescence microscopy. This study also reports for the first time that PEF treatment can enhance fructan leakage from onion bulbs, which means that PEF treatments have the potential to manipulate the fructan contents of some plant-based foods.

Effect of pulsed electric fields on the production of yeast extract by autolysis

Abstract The production of yeast extract by autolysis can be accelerated by treating yeast cell suspensions with pulsed electric fields (PEF) prior to autolysis. The present work is aimed at investigating the effects of PEF on the progress of yeast autolysis. Saccharomyces cerevisiae suspensions (8.3 log CFU/mL in distilled water) were subjected to various PEF treatment conditions (5–20 kV/cm, 1–2000 pulses, 15-μs pulse width) corresponding to various values of cell disintegration index (0–1). Suspensions were then autolyzed and the production of yeast extract was monitored in terms of total protein, amino acid and total solids release. PEF treatment led to an increase of final amino acid and total solids release of 37% and 20%, respectively. Autolysis was described mathematically by a first-order fractional model through which PEF treatment was found to accelerate the progress of autolysis up to 78% compared to untreated samples. Industrial relevance The application of pulsed electric fields (PEF) for the production of yeast extract was studied. The standard lengthy autolysis procedure can be accelerated by the electroporation caused by PEF and increase the extract yield. The present study provides an exploration of the effects of PEF on the kinetics and yield of the autolysis procedure.

Pulsed electric fields as a green technology for the extraction of bioactive compounds from thinned peach by-products

Abstract Thinned fruits are agricultural by-products which nowadays have few economic or environmental benefits. However, previous studies have revealed that these immature fruits have a large amount of antioxidant compounds. The aim of this study was to evaluate whether pulsed electric fields (PEF) might be a suitable green technology for enhancing the extraction of phenols, flavonoids and antioxidant compounds from fresh thinned peaches, thus reducing the use of methanol. Moreover, response surface methodology has been used to determine the optimal PEF treatment conditions, observing that the solvent is the main factor. The highest amounts of bioactive compounds were extracted using 80% methanol and no PEF. Methanol combined with PEF produced a negative effect on the extraction yield. However, the use of water as a solvent increased the amount of total bioactive compounds and individual phenols (chlorogenic acid, coumaric acid and neochlorogenic acid). Thus, PEF-assisted extraction of bioactive compounds from thinned peach fruits using water as a solvent is an alternative to conventional extraction methods which require dried products, large amounts of organic solvents and long extraction times.

Antioxidant activity improvement of identified pine nut peptides by pulsed electric field (PEF) and the mechanism exploration

This study was aimed to explore the mechanism of peptides antioxidant activity improvement treated by pulsed electric field (PEF). The pine nut (Pinus koraiensis Sieb. et Zucc) peptides were used as the experimental materials. DPPH radical inhibition and cellular antioxidant activity (CAA) were applied to evaluate the peptides antioxidant activity. Structures of PEF-treated peptides were analyzed by mid-infrared (MIR) and circular dichroism (CD) spectroscopy. Peptides were indentified including Gln-Cys-His-Lys-Pro, Gln-Cys-His-Gln-Pro, Lys-Cys-His-Gln-Pro(KCHQP), and Lys-Cys-His-Lys-Pro. KCHQP was with the strongest DPPH radical scavenging of 89.10% ± 0.20%, and CAA units of 78.40 ± 1.71. Moreover, the DPPH radical scavenging of KCHQP was significantly increased from 89.10% ± 0.20% to 93.22% ± 0.09% under the PEF treatment conditions (pulse frequency 1800 Hz, and electric field intensity 15 kV/cm). The MIR and CD spectroscopy indicated that the structure of KCHQP was not changed by PEF. However, the zeta potential was reduced from 11.6 ± 0.28 mV to 0.4 ± 0.06 mV. This study enriched the resource of antioxidant peptides with indentified amino acid sequence. It provided a way to investigate mechanism of peptides antioxidant activity improvement treated by PEF.

Metabolic response of fresh-cut apples induced by pulsed electric fields

Abstract Pulsed electric field (PEF) treatments can induce metabolic stress responses in plant tissue as a function of the applied conditions. This study highlighted the metabolic effects of reversible and irreversible electroporation in fresh-cut apple tissue, by adjusting the electric field strength to 100, 250 and 400 V/cm (100 μs pulse width, 60 pulses, 100 Hz). Metabolic heat, O 2 and CO 2 gas analysis, along with metabolomics, were employed to jointly evaluate the PEF-induced effects after 24 h at 10 °C. Marked metabolic changes were registered when the threshold of irreversible electroporation was exceeded, at 250 and 400 V/cm. With such treatments, a drop of metabolic heat and respiration rate was observed, as a probable consequence of the loss of the cell viability, anaerobic respiration pathways were noticeably lowered, while γ-aminobutyric acid metabolism was activated. Conversely, minimal modifications of the metabolism heat and metabolites concentrations were noticed when 100 V/cm was applied. Industrial relevance Metabolic response of fresh-cut fruit and vegetables as function of the manufacturing process is a fundamental aspect directly related to the quality of the final products. Pulsed electric fields (PEF), as well as other innovative technologies, can induce undesired effects on tissue metabolism that might limit the industrial application. Furthermore, the analytical methods used in the present work provide useful tools for the optimization of the PEF treatment conditions for fresh-cut manufacturers.

Influence of the treatment medium temperature on lutein extraction assisted by pulsed electric fields from Chlorella vulgaris

Influence of the of temperature of biomass (10–40 °C) treated by pulsed electric fields (PEFs) at different intensities (10–25 kV/cm) on electroporation of the microalgae Chlorella vulgaris and on the extraction of lutein was investigated. The occurrence of reversible and irreversible electroporation increased with electric field strength and medium treatment temperature. On the other hand, increasing temperature increased the sensitivity of C. vulgaris cells to irreversible electroporation. Response surface methodology was used to identify optimal PEF treatment conditions for enhancing lutein extraction yield (LEY) from fresh C. vulgaris biomass. Considering the cultivation temperature of C. vulgaris (25–30 °C) and the low increase in the LEY when the PEF treatments were applied at temperatures above 30 °C, a treatment of 25 kV/cm–100 μs at 25–30 °C increased the LEY around 3.5–4.2-fold in comparison with the control, resulting in the most suitable treatment conditions for maximizing the lutein extraction at the lowest energy cost. In recent years, industrial interest in microalgae as source of bioproducts such as natural additives or active ingredients for food and cosmetic formulations has arisen. However, there are still several obstacles to fully take advantage, such as the ability to successfully extract these compounds from the cell biomass. Electroporation of microalgae by PEF-technology could be an alternative to conventional cell disruption techniques. Therefore, identifying critical factors affecting the enhancement of bioproduct extraction from microalgae is necessary to establish PEF as a true option. • Increasing medium temperature increased sensitivity towards electroporation. • PEF improved lutein extraction yield up to 4.2-fold compared to the control. • 25–30 °C resulted in the most suitable treatment temperature for subsequent extraction. • PEF-treatments did not cause degradation of lutein extracts.

Upscaling from benchtop processing to industrial scale production: More factors to be considered for pulsed electric field food processing

Pulsed electric field (PEF) processing of juice has been intensively studied with benchtop scale experiments. However, there is still limited information regarding critical factors to be considered for PEF efficacy in microbial reduction with PEF processing during pilot or commercial scale production of juice. In the present study, continuous benchtop (3.6–7.2L/h) PEF processing systems with co-field treatment chambers and bipolar square waveform pulses were used and simulated production conditions were tested for pomegranate juice. Microbial reductions of Escherichia coli, as affected by PEF process conditions (field strength, pulse width, pulse frequency, total treatment time, input energy), production conditions (flow rate, juice holding time and temperature), and juice properties (pH, conductivity, particulate), were investigated. Flow rate, PEF process parameters, production conditions, type of target microorganism, and properties of juice significantly affected microbial reductions by PEF treatments. E. coli ATCC 35218, a non pathogenic surrogate bacterium, exhibited higher resistance to PEF treatments than E. coli O157:H7 and E. coli K12 in pomegranate juice. Increase of a single PEF parameter (field strength, pulse width, pulse frequency, total treatment time, or energy input) is insufficient to achieve maximum microbial reduction. Optimal PEF treatment conditions for maximum microbial reduction depend on multiple factors including PEF processing parameters, production conditions and product properties. This study demonstrates that scale-up and validation studies in a specific PEF system for specific products are very important and necessary before successful commercial application of this novel technology is possible.

Effects of PEF and heat pasteurization on PME activity in orange juice with regard to a new inactivation kinetic model

The inactivation kinetics of pectin methyl esterase (PME) during the shelf life (4°C-180days) of freshly squeezed orange juice samples processed by both pulsed electric fields (PEF) and heat pasteurization (HP) was evaluated in the study. The PME inactivation level after the PEF (25.26kV/cm-1206.2μs) and HP (90°C-20s) treatments were 93.8% and 95.2%, respectively. The PME activity of PEF-processed samples decreased or did not change, while that of HP samples increased during storage (p<0.01). A kinetic model was developed expressing PME inactivation as a function of the PEF treatment conditions, and this enabled the estimation of the reaction rate constant (587.8–2375.4s−1), and the time required for a 90% reduction (De, 3917.7–969.5s). Quantification of the increase in PEF energy to ensure a ten-fold reduction in De (ze, 63.7J), activation electric fields (−921.2kVcm−1mol−1), and electrical activation energy (12.9kJmol−1) was also carried out. Consequently, PEF processing was very effective for the inactivation of PME and for providing stability of orange juice during storage.

Effect of Pulsed Electric Field Treatment on Cold-Boned Muscles of Different Potential Tenderness

Despite the release of several reports highlighting the potential benefits of pulsed electric field (PEF) technology in food processing, there are limited studies on the use of PEF in meat processing, in particular with fresh meat. The effect of PEF on the quality of beef loins (Musculus longissimus lumborum, LL) at 1 day postmortem and topsides (Musculus semimembranosus: SM) at 1 and 3 days postmortem was investigated using a range of treatment combinations [voltages (5 and 10 kV) and frequencies (20, 50 and 90 Hz)]. The investigated parameters were purge loss, cooking loss and meat tenderness (shear force) to identify the optimum PEF treatment conditions for each muscle to evaluate the economic (in terms of purge and cooking losses) and texture benefits of PEF treatments. The tenderness of the loin samples was found to benefit from PEF treatment (19.5 % reduction in the shear force) regardless of the electrical input, whereas the level of tenderness of the topsides was increased by increasing the treatment frequency (4.1, 10.4 and 19.1 % reduction in the shear force at 20, 50 and 90 Hz, respectively). Higher purge loss (%) and lower cooking loss (%) were found in PEF-treated samples. It is interesting to observe that the level of SM tenderness improvement was not dependent on the meat postmortem time up to 3 days which allows greater flexibility in the use of PEF technology.