Effect Of Pulsed Electric Fields Research Articles

Physicochemical and sensory properties of beef muscles after Pulsed Electric Field processing.

This study investigated the effects of pulsed electric field (PEF) processing on the sensory and physicochemical properties of beef biceps femoris (BF) and semitendinosus (ST) muscles. The fresh and frozen-thawed muscles were treated at an electric field strength of 0.8-1.1 kV/cm, pulse width of 20 μs, frequency of 50 Hz and specific energy of 130 kJ/kg. PEF treated samples improved meat tenderness and colour. However increased fat oxidation and increased saturated fatty acids were evident in PEF processed frozen samples. Temporal dominance of sensations results showed that although oxidation was the most dominant in temporal perception, the samples were only found to be detrimental to the sensory quality of PEF processed beef muscles stored for 7 days.

The effects of pulsed electric fields on the quality parameters of freeze-dried apples

In this study, the impact of a pulsed electric field (PEF) treatment on the final quality of freeze-dried apples was investigated. The PEF treatment has been performed at an electric field intensity equal to 1.07 kV/cm and a specific energy input of 0.5, 1 and 5 kJ/kg. The samples were freeze-dried (without a separate pre-freezing step) at varying temperatures (set on 40 °C and 60 °C) and pressures (0.1, 0.25 and 1 mbar). The quality of dried material was evaluated by the analysis of residual moisture content, macro- and microscopic properties, colour, the total content of phenolic compounds and the antioxidant activity as well as texture and acoustic properties. It was found that the residual moisture content of PEF treated samples was reduced by up to ∼82% in comparison to the intact tissue. For electroporated samples, a good preservation of macro-shape, an inhibition of shrinkage and the development of large pores were observed. The PEF treated material exhibited a higher total phenolic content, but a smaller antioxidant activity. Mechanical and acoustic analysis showed a higher crunchiness and brittleness for PEF-treated tissue, whereas untreated tissue was characterised by a harder and rather crackly texture.

Effect of Pulsed Electric Fields (PEF) on the ultrastructure and in vitro protein digestibility of bovine longissimus thoracis

Pulsed Electric Fields (PEF) has recently been extended to designing appetising and wholesome food products, such as tenderised meat. This process induces structural changes in foods that could affect their digestive properties. The objective of this research was to investigate the effect of PEF on the ultrastructure and in vitro protein digestibility of beef muscle. Two days post-mortem beef longissimus thoracis was PEF-treated using electric field strength of 1.00–1.25 kV/cm at two different pulse numbers of 500 and 2000. The moisture content of the PEF-treated samples was significantly lower (p < 0.05) by 1.3%–4.6% than the untreated samples while their pH, colour and protein thermal profile remained unchanged. Transmission electron micrographs showed the weakening of the Z-disk and I-band junctions of PEF-treated samples and their sarcomeres were 25%–38% longer than the control. PEF treatment improved in vitro protein digestibility by at least 18% (up to 31%) and the digestive profiles (SDS-PAGE) of both control and PEF-treated samples were different. This corresponds to more severe Z-disks and I-bands disruption observed in PEF-treated samples after 180 min of simulated digestion, showing that the PEF-treated muscle is more susceptible to enzymatic degradation.

Multi-Parametric Study of the Viability of in Vitro Skin Cancer Cells Exposed to Nanosecond Pulsed Electric Fields Combined With Multi-Walled Carbon Nanotubes.

Multi-walled carbon nanotubes with excellent electrical properties and high aspect ratios can reduce the high field strength required to kill cancer cells in vitro with nanosecond pulsed electric fields. For the first time, this article systematically and comprehensively evaluates the effects of various parameters of nanosecond pulsed electric fields combined with multi-walled carbon nanotubes on cell viability. The effects of field strength, E (2-10 kV/cm); pulse width, τ (100-500 ns); and pulse number, N (5-260) on the viability of A375 human skin cancer cells in the presence of multi-walled carbon nanotubes are studied using the Cell Counting Kit 8 assay. Based on a logistic model, the relationship between cell viability and various parameters is obtained using 1-dimensional nonlinear fitting. The results show a sigmoid-type variation in cell viability with field strength, pulse width, or pulse number. Multivariate scaling analysis shows that the relationship between cell viability and the pulse energy density σE2τN can be described as a sigmoid type. The introduction of multi-walled carbon nanotubes does not affect the above rules but significantly enhances the killing effect of nanosecond pulsed electric fields, which could effectively improve the electrical safety of nanosecond pulsed electric fields for the treatment of tumors.

Электрическая проводимость и устойчивость мембран ооцитов мыши к действию импульсного электрического поля в растворах криопротекторов

Using the method of pulsed conductometry, the values of electric conductivity of mouse oocytes in 1.0 M solutions of penetrating cryoprotectants have been first determined and the stability of their plasma membranes to the effect of pulsed electric field of increasing intensity has been investigated. For the oocytes, incubated in ethylene glycol (EG), 1,2-propanediol (1,2-PD), 2,3-butanediol (2,3-BD) and dimethyl sulfoxide (DMSO) solutions, the electric conductivity values were (23.6 ± 3.4), (21.3 ± 5.8) and (21.0 ± 2.3) and (23.6 ± 7.1) μS/cm respectively. The values of electric conductivity for mouse oocytes in acetamide (AC) and formamide (FA) solutions were (16.5 ± 6.1) and (16.9 ±± 10.7) μS/cm, respectively. Cryoprotectant solutions, belonging to alcohols (EG, 2,3-BD), as well as DMSO, were shown to have a stabilizing effect on the mouse oocyte plasma membranes under electric field action. The AC and FA solutions caused no stabilizing effect on mouse oocyte membranes, which was manifested in development of irreversible electric breakdown of plasma membranes with increasing electric field intensity. Probl Cryobiol Cryomed 2018; 28(4): 311-321

Pulsed electric field improved protein digestion of beef during in-vitro gastrointestinal simulation

Effect of pulsed electric field (PEF) on in-vitro simulated gastrointestinal protein digestion of cold-boned beef Semimembranosus was elucidated. PEF treated [T1, 5.0 kV (90 Hz); T2, 10 kV (20 Hz)] samples along with control were subjected to in-vitro simulated gastrointestinal protein digestion. Samples collected at 0, 30 and 60 min of gastric digestion and 120 and 180 min of intestinal digestion were analysed for protein digestibility (%), soluble protein (%), protein profile (SDS-PAGE), free amino acid analysis and mineral profile. Significantly higher (P < 0.05) protein digestibility (%) and soluble protein (%) values were observed for PEF treated samples. No negative impact (P > 0.05) of PEF was observed on the release of various minerals from the muscle during the digestion. By modifying the protein profile of the meat digests, PEF processing had a positive influence on in-vitro digestion kinetics that led to a faster and greater digestion of proteins during simulated gastrointestinal digestion.

Effect of pulsed electric field on structural properties and digestibility of starches with different crystalline type in solid state

Effect of pulsed electric field (PEF) on the structural properties of representative starches with different crystalline type, wheat starch for type A, potato starch for type B, and pea starch for type C, were investigated with polarized light microscopy (PLM), X-ray diffractometry (XRD), attenuated total internal reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, solid-state nuclear magnetic resonance (SSNMR) spectroscopy, small-angle X-ray scattering (SAXS), and gel permeation chromatography (GPC) to understand whether PEF could be applied directly in starchy foods. The results showed that PEF could change the structure of all three types of starch, especially potato starch; the birefringence, represented by Maltese cross in polarized microscopic observation changed slightly; XRD and SSNMR spectra demonstrated PEF did not change the crystalline type of starch granules. However, relative crystallinity variations happened at some points of electric field intensity (EFI). Increasing with the EFI, a bigger variation of R1045/1022 happened in potato starch than in wheat starch and pea starch, as illustrated by ATR-FTIR. Significant influences of PEF on the scatter structure and fractal dimension of self-similar structures were observed for wheat starch and potato starch, but not for pea starch. The GPC suggested that molecular weight distribution changed for all the three starches. And in vitro tests showed that PEF changed significantly (P < 0.05) the digestibility of starches, especially wheat starch and potato starch.

Convective air, microwave, and combined drying of potato pre-treated by pulsed electric fields

The effects of pulsed electric field (PEF) treatment on drying of potato have been investigated. The convective air (CA) (T = 50 °C), microwave (MW), and combined (CA + MW or MW + CA) drying was applied. The drying curves, progression of temperature inside samples, microstructure, and capillary imbibition capacity of untreated (U) and PEF treated samples were compared. The PEF treatment noticeably affected the CA and MW drying characteristics and structure of dried samples. It reflected impact of electroporation on the heat and mass transfer processes during the different drying periods. The different progressions of temperatures inside U and PEF samples for the MW mode of drying were revealed. The highest and smallest rehydrations were observed for the U samples for individual CA and MW modes of drying, respectively. The observed behavior was explained accounting for the absence of starch gelatinization for the CA mode of drying and presence of it for the MW mode of drying.

Enhancing hydroxycinnamic acids and flavan-3-ol contents by pulsed electric fields without affecting quality attributes of apple

Pulsed electric fields (PEF) have arisen as a promising tool for enhancing plant-based food bioactive compounds, although side effects on quality attributes might compromise consumer acceptance. This work was aimed at filling the gap in the understanding of whole effects of PEF on apple phenolic compounds profile and quality parameters. Treatment specific energy was a critical factor affecting phenolic profile and quality attributes, which in turn varied from 0 to 24 h after treatment. Treatments at 1.8 and 7.3 kJ kg−1 (140 and 260 μs total treatment times, respectively) induced important quality changes, mainly discoloration and firmness loss, while overall phenolic contents decreased, except those of flavonols. However, 24 h after treatment at 0.01 kJ kg−1 (20 μs total treatment time), the main apple phenolic compounds as determined by HPLC-DAD-MS had enhanced contents (28% 5-caffeoylquinic acid; 35% procyanidin B2). Accordingly, total phenolics and total flavan-3-ols contents increased (26% and 35%, respectively), while physicochemical quality attributes were not affected. Therefore, 0.01 kJ kg−1 PEF treatment is proposed for obtaining apples with optimal quality and enhanced functional value.

Pulsed electric field effects on inactivation of microorganisms in acid whey

Prospects of pulsed electric field technology application on acid whey concentrate pretreatment were analyzed. Stationary and flow pre-treatment systems were combined with different treatment parameters: electric field strength (E = 39 kV/cm, 95 kV/cm, 92 kV/cm), pulse duration (τ = 60 ns, 90 ns, 1000 ns) and pulse number (pn = up to 100 pulses). Isolates of Saccharomyces sp. and Lactobacillus sp. were predominant in concentrate. Significant non-thermal inactivation effect was achieved after PEF treatment. Exposure to short pulses selectively inactivated yeast cells, as a result PEF technology can be applied for low-energy acid whey processing.

Pulsed electric field: Effect on in-vitro simulated gastrointestinal protein digestion of deer Longissimus dorsi

The effect of pulsed electric field (PEF) on in-vitro simulated gastrointestinal protein digestion of cold-boned deer Longissimus dorsi was elucidated. PEF treated samples viz. T1 (2.5 kV, 50 Hz) and T2 (10 kV, 90 Hz) along with a control were subjected to in-vitro simulated gastrointestinal protein digestion. Samples were collected after 0, 30, and 60 min of gastric digestion and 120 and 180 min of intestinal digestion. A significant (P < 0.05) increase was observed in the protein digestibility and soluble protein (%) of PEF treated samples, highlighting a positive influence of PEF processing on the digestion process. Higher concentrations of almost all the free amino acids were observed for the PEF treated samples. No significant effect of PEF was observed on the release of various minerals. PEF may be utilized for the development of novel muscle foods with improved protein digestibility.

Effect of pulsed electric field on calpain activity and proteolysis of venison

Abstract The present study evaluated the effect of pulsed electric field (PEF) on the calpain activity, proteolytic pattern and myofibrillar protein profile of cold-boned Longissimus dorsi obtained from red deer (Cervus elaphus). PEF treated samples, T1 (2.5 kV, 50 Hz) and T2 (10 kV, 90 Hz) and a non-treated control were aged for 21 days at 4 ± 1 °C. The samples were analysed for shear force (N), myofibrillar fragmentation index (MFI), calpain activity, proteolysis of desmin and troponin-T and myofibrillar protein profile (SDS-PAGE). No significant impact of PEF was observed on the shear force and MFI. A slight increase was recorded in the calpain activity and proteolysis of troponin-T, suggesting a tendency of PEF to improve the tenderization process. Collectively, the results from casein zymography, Western blotting and myofibrillar protein profile suggest that PEF did not produce any significant impact on the tenderization process of venison.

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.

Impact of Pulsed Electric Fields on the Volatile Compounds Produced in Whole Onions (Allium cepa and Allium fistulosum).

The objective of this research was to investigate the effect of pulsed electric field (PEF) processing on the volatile compounds produced in onion cultivars. The changes in the volatile compounds of onions were assessed comparing results observed while measured immediately and 24 h after PEF treatment using headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC-MS). Significant increases in the concentrations of propanethial S-oxide, propenyl propyl thiosulfinate, 2-methyl-2-pentenal, dipropyl disulfide, propenyl propyl disulfide, methyl propyl disulfide, and methyl propenyl disulfide were observed immediately after PEF treatment. The concentrations of propenyl propyl thiosulfinate, dipropyl disulfide, methyl propyl disulfide, dipropyl trisulfide, methyl propyl trisulfide, and propenyl propyl trisulfide increased after 24 h compared to initial concentrations. It is postulated that these changes are due to PEF-induced cell permeabilisation that facilitates enzyme-substrate reactions after the PEF treatment.

Process optimisation of pulsed electric fields pre‐treatment to reduce the sous vide processing time of beef briskets

SummaryThis study used multiple regression to model the effect of pulsed electric field (electric field strengths 0.7, 1.0 or 1.5 kV cm−1) and sous vide (60 °C for either 12, 18 or 24 h) processing on the quality parameters (tenderness, cooking loss, colour, lipid stability) of beef brisket. Pulsed electric fields (PEF) at 0.7 kV cm−1 and 1.5 kV cm−1 followed by sous vide processing for 12–20.2 and 20.8–23.7 h, respectively gave the lowest values for hardness (&lt;20.2 N), shear force (100.5 N mm−1 s−1) and cooking loss (&lt;17.4%). PEF treatment prior to sous vide processing had no significant effect on lipid oxidation, colour stability, cooking loss or in vitro protein digestibility of sous vide‐processed brisket. Increasing the electric field strength and/or prolonging the sous vide time significantly increased collagen solubilisation in the sous vide brisket. This study demonstrated that a PEF pre‐treatment can reduce sous vide processing time while enhancing the tenderness of tough meat cuts.

The Effect of Pulsed Electric Field on the Generation of Charge in Flow-Based Medical and Diagnostic Systems

The aim of this study is to consider the effect of pulsed electric field on the process of charge generation caused by motion of water in flow-based systems widely used in medical proteomic and diagnostic devices. It has been demonstrated that the use of pulsed electric field leads to an increase in the value of charge generated during the motion of the liquid (~ 80%, T = 35°С). The observed effect should be taken into account in the development of novel highly sensitive flow-based diagnostic systems

Comparative Study of Phenolic Profile and Content in Infusions and Concentrated Infusions of Buddleja Scordioides Treated by High-Intensity Pulsed Electric Fields (HiPEF)

The effect of high-intensity pulsed electric fields (HiPEF) has been reported on the microbial resistance of fruit juices and beverages. However, the influence of HiPEF on bioactive compounds in herbal infusions is still limited. The objective of the present work was to evaluate chemical stability of polyphenols of infusions from Buddleja scordioides or Salvilla under thermal processing (concentrates) followed by HiPEF treatments. Buddleja infusions were prepared at 1% w/v of salvilla, heated, filtered and concentrated in a thin falling film evaporator. Three different HiPEF treatments were applied to Buddleja scordioides concentrated beverages. The percentage of pulse rate was 25 and 90%; output temperature, 18.3 ± 1 °C; and the frequency range, 100, 300 and 400 Hz. The feed flow was 0.5 L/h. DPPH radical scavenging assay, inhibition of Nitric Oxide activity and analysis of phenolic acids and flavonoids by UPLC-ESI-MS/MS were determined. ANOVA one-way analysis and Tukey test (p &lt; 0.05) were used to analyze results. Concentration process increases the amount of flavonols; however, the use of HiPEF produces a minor reduction on antioxidant capacity. The use of HiPEF at 1000 kJ/kg and 1100 kJ/kg displays a similar profile on phenolic acids between HiPEF-treated beverages and concentrates, showing that the use of HiPEF may be a promissory technology in the processing practices of herbal infusions.

Continuous pulsed electric field treatments’ impact on the microbiota of red Tempranillo wines aged in oak barrels

The effects of pulsed electric field (PEF) technology on the microbiota of wines aging in oak barrels without additional chemical preservatives were studied. Two differently aged wines without sensory deviations, naturally having Brettanomyces/Dekkera, were PEF-treated. Results showed that the PEF treatment in continuous flow inactivated the most abundant spoilage microbial population of each wine. However, the recovery of some microorganisms after treatment was also observed. Therefore, to determine PEF as an alternative to the use of SO2, additional studied are needed with a wider sampling set.

Pulsed electric fields treatment at different pH enhances the antioxidant and anti-inflammatory activity of ovomucin-depleted egg white.

This research investigated the effects of pulsed electric fields (PEF) (1.4-1.7 kV/cm, 653-695 kJ/kg) and heating (60 and 80 °C for 10 min) at different pH (4, 5, 7, and 9) on the antioxidant and anti-inflammatory activity of ovomucin-depleted egg white (OdEW) after in vitro gastrointestinal hydrolysis. PEF and heating (80 °C for 10 min) at pH 4 enhanced the antioxidant activity of the whole hydrolysates, chemically determined using DPPH and ORAC assays. Furthermore, the anti-inflammatory activity of protein hydrolysates was assessed in lipopolysaccharide-stimulated HT-29 cells using ELISA assay. PEF and heating at pH 4 enhanced the anti-inflammatory activity of the whole hydrolysates dose-dependently. Hydrolysates at 1 mg/ml showed similar inhibition (35.5% and 35.9%) of interleukin-8 production, due to PEF treatment and heating (80 °C for 10 min), respectively. Results indicated that prior PEF treatment can analogously enhance both antioxidant and anti-inflammatory activity of OdEW hydrolysates to heating, with potentially reduced thermal input.

Pulsed electric field: Role in protein digestion of beef Biceps femoris

Abstract The present study was conducted to evaluate the effect of pulsed electric field (PEF) on the protein digestion kinetics of cold-boned beef Biceps femoris during in-vitro simulated gastrointestinal digestion. Muscle was treated with PEF at 5 kV, 90 Hz, 20 μs (T1) and 10 kV, 20 Hz, 20 μs (T2) and subjected to in-vitro gastrointestinal digestion along with an untreated control. Samples were collected at 0, 30, and 60 min of gastric digestion and 120 and 180 min of intestinal digestion. PEF processing affected the digestion kinetics by modifying the protein profile (SDS-PAGE) of the meat digests and significantly (P 0.05) impact was observed on the release of minerals such as Fe, Zn, Cr, Cu, Mg, Ni, Na or K. PEF processing improved the digestion kinetics of the beef muscle during gastrointestinal digestion simulation. Industrial relevance PEF processing has already been reported to improve the tenderization of beef muscles during ageing process. The simulations and experiments conducted in this work showed that PEF processing has the potential to improve the protein digestion kinetics of beef muscle during in-vitro gastrointestinal digestion and could be utilized for the development of novel muscle foods and protein structures with improved digestibility and nutritive value.