High-intensity Pulsed Electric Fields Research Articles

Numerical study of the effects of pulsed electric field on β-casein

As a non-thermal microbial inactivation technology, pulsed electric field (PEF) treatment can be used in liquid food sterilization. It is necessary to investigate the effects and mechanisms of PEF on the important contents of liquid food. In this study, molecular dynamics (MD) simulation and multiple structural analyses were employed to investigate the effects of PEF on β-casein (BCN) molecule. The investigation focused on examining the impact of PEF on molecular conformation, flexibility, electrostatic properties, and solvent interactions. Results found that high-intensity pulsed electric fields can cause irreversibly complete unfolding of BCN molecule within a picosecond timeframe. The applied PEF changed the dipole moment of BCN molecules, leading to the reorientation of residues towards the direction of the applied electric field. Furthermore, the electric field-induced movement of hydrophobic and hydrophilic residues within the BCN molecules was observed, resulting in concomitant changes in the solvent accessible surface area (SASA) of BCN molecule.Industrial relevance: PEF is an emerging non-thermal processing technology in the food industry. MD simulations were employed to investigate the conformational changes of BCN under different pulse electric fields and exposure times. Our study elucidates the fundamental mechanism of PEF's interaction with protein molecules and may contribute to improving the functional properties of this protein. Analysis at the molecular level can be experimentally validated, providing a theoretical foundation for the widespread application of PEF technology in protein-containing food systems.

High-intensity pulsed electric field-assisted acidic extraction of pectin from citrus peel: Physicochemical characteristics and emulsifying properties

Sustainable innovation seeks more energy-efficient processes for producing highly demanded products from industrial by-products. This study follows this endeavor. Comparisons were made on two processes for producing pectins from citrus peel as well as the two derived pectin products: a high-intensity pulsed electric field (HIPEF) pretreatment of citrus peel powder followed by a milder acidic extraction (pH 2, heating at 70 °C for 1 h; pectin termed HIPEF-CP), and a conventional direct hot-acid extraction (pH 2, heating at 90 °C for 2 h; pectin termed CP). HIPEF-assisted extraction significantly improved pectin yield (by 8.48%) and production efficiency (by 100.23%) while reducing energy consumption. Both were low-methoxyl pectins with similar branching degrees and contents of rhamnogalacturonan-I (RG-I), protein, phenolic compounds, total alkaloids and vitamin C. Compared with CP, HIPEF-CP contained higher homogalacturonan content, higher galactose content, higher galacturonic acid content, lower arabinose content, lower xylose content, slightly lower degree of methyl esterification, higher linearity, lower side chain size, higher molecular weight, and wider molecular weight distribution. The antioxidant, emulsifying and emulsion-stabilizing abilities of HIPEF-CP were superior to those of CP, though both pectins were satisfactory emulsifiers, exhibiting good antioxidant activities and emulsifying capacities at pectin concentrations not lower than 1.0%. The HIPEF pretreatment of citrus peel made the subsequent acidic pectin extraction feasible under milder conditions, to produce pectin with desired antioxidant and emulsifying capacities.

Mung bean protein isolate treated with high-intensity pulsed electric field: characteristics and its use for encapsulation of Asian seabass oil

Aim To modify the techno-functional properties of mung bean protein isolate (MBPI) by high-intensity pulsed electric field (HIPEF) treatment and to apply the treated MBPI for encapsulation of Asian seabass oil (ASO). Methods MBPI was prepared using isoelectric precipitation. HIPEF was applied to MBPI solutions at 25 kV/cm with varying pulse numbers (0–400). Physicochemical properties and structure of MBPI were assessed. ASO microcapsules prepared using HIPEF-treated protein as wall material was characterised and tested for storage stability. Results Solubility, surface hydrophobicity, total sulfhydryl content, and emulsifying property of MBPI increased and β-sheets and α-helix were altered after HIPEF treatment at pulse number of 300. ASO microcapsules possessing spherical shape with surface indentations had EE of 72.07 ± 5.08%. ASO capsules had lower lipid oxidation than the control during storage. Conclusion HIPEF improved techno-functional properties of treated MBPI. Treated MBPI could be used as wall material for encapsulation of fish oils.

Large amplitude density fluctuations in a lipid bilayer, induced by picosecond electric pulses, and their possible biotechnological applications

Electroporation refers to changes in permeabilization of lipid membranes induced by external pulsed electric fields. Diverse applications of electroporation in biotechnology include gene transfer, modulation of gene expression, cell proliferation, seed germination, sterilization in the food industry, and extraction of chemical compounds. We argue that the formation of large amplitude, subnanometer density fluctuations in lipid bilayers, induced by high-intensity pulsed electric fields with picosecond durations, may produce lipid nanopores and change transmembrane transport, which trigger cellular signalling pathways with subsequent cellular responses and changes in cell physiology, thus, could represent perspectives regarding the development of electroporation biotechnologies.

Understanding the effect of meat electrical conductivity on Pulsed Electric Field (PEF) process parameters and the ability of PEF to enhance the quality and shorten sous vide processing for beef short ribs

The aim of this research was to investigate how the electrical conductivity of short ribs affected Pulsed Electric Field (PEF) process parameters and the ability of PEF to enhance their quality and reduce sous vide (SV) processing time. Short ribs with different range of electrical conductivity (3–6, 6–9, and 9–12 mS/cm) values were treated using input voltage of 10 kV, pulse width of 20 µs, pulse frequency of 50 Hz and pulse number, of either 1600 (low intensity PEF/LPEF) or 5200 (high intensity PEF/HPEF), followed by SV processing at 60 °C for either 24 or 36 h. The quality parameters assessed were cooking loss (%), Texture Profile Analysis (TPA) parameters, and Commission Internationale d’Eclairage (CIE) L*a*b* colour parameters. There was a variation in electrical conductivity of short ribs according to the position of the bone in the short rib, which demonstrated good congruence with the distribution of fat and connective tissue. SV processing with or without PEF pre-treatment did not have a significant effect (p > 0.05) on cooking loss or CIE L*a*b* colour parameters. Short ribs with a medium conductivity (6–9 mS/cm) had a significantly lower hardness after high intensity PEF followed by SV for 24 h, whilst short ribs with an average conductivity of 3–6 and 9–12 mS/cm required longer SV time (up to 36 h) and had a significantly lower hardness compared to non PEF pre-treated samples. TPA values of short ribs treated with the same PEF intensity and SV processing parameters were comparable regardless of the short ribs initial electrical conductivity, which indicates that PEF treatment could ameliorate the biological electrochemical variability inherent to short ribs and PEF could be the potential tool to decrease their SV processing time and enhance their tenderness.

The Application and Optimization of HIPEF Technology in the Processing of Juice from Strawberries Harvested at Two Stages of Ripeness.

The aim of this study was to investigate the influence of high intensity pulsed electric field (HIPEF) technology on the stability of total phenols, anthocyanins, hydroxycinnamic acids, flavonols, and condensed tannins in strawberry juices (Fragaria x ananassa Duch. cv. ‘Albion’) with different ripening stages (75% and 100%) and stored at +4 °C for 7 days. The HIPEF parameters studied were: (i) electric field strength (40 and 50 kV cm−1), (ii) frequency (100 and 200 Hz), and (iii) treatment duration (3 and 6 min). Of the HIPEF parameters studied, electric field strength and frequency had a statistically significant effect on the content of all phenolic compounds. Treatment duration showed no statistically significant effects on phenolic compounds except for flavonols and condensed tannins. Storage had a positive effect on the stability of most of the phenolic compounds, with the exception of flavonols. Optimization of HIPEF processing showed that strawberry samples at both ripeness levels were suitable for HIPEF treatment to obtain functional fruit juices with a high content of polyphenols.

Screening the Antioxidant Activity of Thermal or Non-Thermally Treated Fruit Juices by In Vitro and In Vivo Assays

The health benefits of fruit juices have been associated with their high content of antioxidant compounds. Commercial juice has been traditionally heat-processed to destroy microorganisms and enzymes. However, high temperatures induce undesirable changes in the nutritional value of the juice. High-intensity pulsed electric fields (HIPEF) are being studied as an alternative to heat treatments. In addition, in vitro and in vivo methods have been recommended to determine the antioxidant potential of juices in a complementary manner. Thus, the antioxidant activity of untreated, high-intensity pulsed electric fields (HIPEF) or heat-treated fruit juices (tomato, apple, pineapple and orange) was studied using in vitro (TEAC, DPPH, FRAP and Folin-Ciocalteu) and in vivo assays (Saccharomyces cerevisiae). Vitamin C and total phenolic compounds in these juices were determined. The highest antioxidant activities (12.01 mmol of Trolox/L) were obtained through the Folin-Ciocalteu assay in orange juices. The lowest values (0.119 mmol of Trolox/L) were found in apple juice analysed by the FRAP assay. Vitamin C content varied from 10 mg/L (orange juice) to 344 mg/L (orange juice). The highest concentration of total phenolic compounds was determined in orange juice (1238 mg/L), whereas the lowest value was found in tomato juices (149 mg/L). The effect of HIPEF and thermal processing on the antioxidant potential of juices depended on the fruits used to prepare the juices and the antioxidant activity assay conducted. Vitamin C concentration was directly related to the antioxidant activity analysed by Folin-Ciocalteu and FRAP methods and the S. cerevisiae growth rate. S. cerevisiae yeast can be used as a feasible in vivo assay to further determine the antioxidant activity of fruit juices.

Identification and Optimization of a Novel Taxanes Extraction Process from Taxus cuspidata Needles by High-Intensity Pulsed Electric Field.

Taxanes are a series of natural compounds with great application potential in antitumor therapy, whereas the lack of efficient taxanes extraction methods significantly hinders the development of taxanes. The high-intensity pulsed electric field (PEF) is a novel technology used to extract bioactive ingredients from food and other natural products. However, the prospect of using PEF for taxanes extraction remains to be elucidated. Herein, we extracted taxanes from Taxus cuspidata via PEF and explored the effects of seven extraction conditions on the yields of target compounds. The Placket–Burman design (PBD) assay revealed that electric field strength, pulse number, and particle size are key factors for taxanes extraction. The response surface methodology (RSM) and back-propagation neural network conjugated with genetic algorithm (GA-BP) were further used to model and predict the optimal extraction conditions, and GA-BP exerted higher reliability, leading to a maximum extraction yield of 672.13 μg/g under electric field strength of 16 kV/cm, pulse number of 8, particle size of 160 meshes, solid–liquid ratio of 1:60, a single extraction, centrifugal speed of 8000 r/min, and flow rate of 7 mL/min, which was 1.07–1.84 folds that of control, solid–liquid extraction (SL), and ultrasonic extraction (US) groups. Additionally, the scanning electron microscopy (SEM) results indicated that the sample particles extracted by PEF method exhibited a coarser surface morphology. Thus, we present for the first time that PEF is feasible for the extraction of taxanes from Taxus cuspidata and highlight the application value of the PBD, RSM, and GA-BP models in parameters optimization during extraction process.

Spatial mechanistic modeling for prediction of 3D multicellular spheroids behavior upon exposure to high intensity pulsed electric fields

<abstract> <p>The objective of this work was to investigate the growth specificities of cancer cells spheroids subjected to pulsed electric field. Multicellular HCT-116-GFP spheroids were exposed to different electric field intensities and the volume of multicellular spheroids was monitored by fluorescence and bright field microscopy. Thanks to an advanced mathematical model, based on differential equations and well-adapted estimation strategies, our modeling enables us to characterize the multicellular spheroids growth after permeabilizing pulsed electric field. In particular, we identify the percentage of cells which are destroyed and the percentage of cells which exhibit an altered growth pattern for different magnitudes of the electric field. We also quantify the growth resumption upon reversible and partially irreversible electroporation. Our preliminary results provide a first quantification of the impact of electroporation on multicellular spheroids growth, and suggest a booming growth of partially irreversible electric pulses, leading to an accelerated regrowth.</p> </abstract>

Recent, Bioelectricity-Related Articles Selected by Ann M. Rajnicek, Media Editor of Bioelectricity.

Recent, Bioelectricity-Related Articles Selected by Ann M. Rajnicek, Media Editor of Bioelectricity.

In vitro bioaccessibility of isoflavones from a soymilk-based beverage as affected by thermal and non-thermal processing

High Pressure Processing (HPP) and High Intensity Pulsed Electric Fields (HIPEF) are non-thermal processing technologies used for obtaining safe and high-quality foods and beverages. In the present work, the changes on both the concentration and the bioaccessibility of isoflavones from treated (thermally and non-thermally) and untreated soymilk-based beverages were evaluated. Thermal treatment (TT) was applied at 90 °C for 1 min, HPP: 400 MPa at 40 °C for 5 min and HIPEF: 35 kV cm−1 with 4 μs bipolar pulses at 200 Hz for 1800 μs. Later, beverages were subjected to an in vitro gastrointestinal digestion for obtaining the bioaccessibility. Thermal and non-thermal processing increased the isoflavone concentration up to 25–26% in TT and HIPEF treated beverages, and up to 38.52% in HPP treated. After in vitro digestion, the concentration of isoflavones in non-thermally processed beverages was higher (70.55% for HIPEF and 98.77% for HPP) than that TT processed (18.52%). HIPEF processing and HPP increased the isoflavone bioaccessibility up to 35.40 and 47.32%, respectively, regarding the untreated product. These results demonstrate that both non-thermal processing technologies HIPEF and HPP are suitable for obtaining high quality and nutritious beverages by improving their isoflavone bioaccessibility.

Targeted gold nanorods combined with low-intensity nsPEFs enhance antimelanoma efficacy in vitro

High-intensity nanosecond pulsed electric fields (nsPEFs) are a novel treatment with promising applications for cell stimulation and tissue ablation, and many research studies have shown that gold nanorods (GNRs) are high-conductivity nanomaterials that can enhance electroporation for biomedical applications. In addition, the folic acid (FA) receptor has been demonstrated as a valuable therapeutic target that is highly expressed in a variety of cancers. To reduce the electric field strength required to treat tumors by nsPEFs, for the first time, gold nanorods with folic acid were proposed to achieve higher antimelanoma efficacy at lower electric field intensity in this study. The surface of polyethylene glycol-gold nanorods with good biocompatibility was further modified by folic acid (FA) to provide modified gold nanorods (GNR-PEG-FA) with specific targeted recognition of A375 melanoma cells. The binding of GNRs to A375 melanoma cells was observed by dark field microscopy. After combined treatment with nsPEFs and GNRs, cell viability was evaluated by a CCK-8 assay. Flow cytometry was performed to evaluate apoptosis and the cell cycle. And active caspase 3 was also detected after treatment. The antimelanoma efficacy was enhanced in a pulsed electric field-dependent manner. More importantly, compared with the group of nsPEFs alone and gold nanorods without FA, treating cells with nsPEFs combined with GNR-PEG-FA resulted in a lower percentage of viable cells, higher percentages of necrosis and apoptosis and higher concentration of active caspase 3 and induced cell cycle arrest in S phase, effectively inhibiting the proliferation of A375 melanoma cells. nsPEFs combined with GNR-PEG-FA showed the best antimelanoma efficacy in vitro and effectively killed melanoma cells with low-intensity nsPEFs. The combined treatment of cells with nsPEFs and GNR-PEG-FA is expected to become a safer and more efficient physical treatment of melanomas.

Ultrastructural changes in hepatocellular carcinoma cells induced by exponential pulses of nanosecond duration delivered via a transmission line

Clinical applications of high-intensity pulsed electric fields have proven useful in ablating solid tumors. However, novel ideas for the development of an effective tumor ablation device are urgently needed. Here, we studied cellular effects of the nanosecond exponential pulse, which is generated by a capacitor-discharging circuit and delivered via a transmission line. Pulses of peak voltage boosted by transmission line oscillation possess high capability to induce swelling and to cause loss of viability in cells. The appropriate parameter of the pulse was selected to investigate the ultrastructural changes in swollen cells, which present smoothened plasma membrane, loss of microvilli, and lowered cytoplasm electron density. We propose the equivalent force field hypothesis to understand the mechanism underlying cell swelling induced by pulsing. Wrinkles on the plasma membrane might indicate recovery from cell swelling, and this was verified by co-culture of pulsed PKH26-Cells with sham-treated PKH67-Cells. We concluded that the ultrastructural changes, such as irregular pores formed on the plasma membrane, were mainly induced by the effect of electric pulse applied on the charged molecules in the membrane.

High-intensity pulsed electric fields or thermal treatment of broccoli juice: the effects of processing on minerals and free amino acids

This research evaluated the influence of high-intensity pulsed electric fields (HIPEF) parameters, electric field strength (15–35 kV/cm), treatment time (500–2000 μs) and polarity (monopolar or bipolar mode) on minerals and free amino acids content of broccoli juice. Additionally, HIPEF-processed broccoli juice was compared with thermally treated (90 °C/60 s) and untreated juices. In general, HIPEF parameters significantly influenced the content of minerals and free amino acids, except Cu, S, P, Trp, Ala, His, and Tyr, which were not influenced by electric field strength, treatment time and/or polarity. At the strongest HIPEF conditions (35 kV/cm for 2000 μs) in bipolar mode, an increment or not significant changes in the mineral content in comparison to fresh broccoli juice was observed. Iron (214.2%), manganesus (117.7%) and zinc (148.4%) were the minerals with the greatest relative augment. While, the highest amino acid retention was histidine (159.3%), and lysine (157.8%). Increment in mineral content was associated to electrode corrosion; while the increase in amino acid content was related to the increment in the activity of enzymes associated with their biosynthesis. Changes in the content of free amino acids depended on HIPEF treatment conditions applied and the amino acid evaluated. Significant losses of minerals and free amino acids were reached after thermal processing of broccoli juice. Overall, HIPEF-treated broccoli juice had superior mineral and free amino acids content than those thermally treated.

Optimization of high-intensity pulsed electric field-assisted extraction of procyanidins from Vitis amurensis seeds using response surface methodology

Procyanidins (PC) from Vitis amurensis seeds was extracted using high-intensity pulsed electric field (PEF). The process parameters including pulse number, electric field strength, ratio of material to liquid and ethanol concentration were studied using response surface methodology, and extraction yield of the extracts were determined. Antioxidant activity of the extracts by PEF, ultrasonic-assisted extraction (UAE), microwave-assisted extraction (MAE) and ethanol extraction (EAE) were compared based on total antioxidant capacity, DPPH radical scavenging capacity and ferrous ion chelating activity. The results revealed that the optimization of conditions of PEF are: pulse number 10; electric field strength 25 kV/cm; ratio of material to liquid 1:21 g/mL; ethanol concentration 63% (v/v), and the PC yields reached 8.23% under this condition. The PEF resulted in a highest extraction yield of PC among the four extraction methods. There was no significant difference in total antioxidant capacity of PC obtained by four methods, the DPPH radical scavenging capacity and ferrous ion chelating activity of PC extracted by PEF were close to that of UAE and MAE, which were superior to EAE. These showed that PEF was an effective method for extracting PC.

Impact of critical high‐intensity pulsed electric field processing parameters on oxidative enzymes and color of broccoli juice

This research evaluated the influence of high-intensity pulsed electric field (HIPEF) processing parameters, electric field strength, treatment time, and polarity on color difference (∆E*), polyphenol oxidase (PPO), and lipoxygenase (LOX) activities in broccoli juice. An optimization of HIPEF processing was accomplished and compared with thermal treatment (90°C/60 s). The lowest RALOX (68.71%) and RAPPO (36.11%) were reached at the strongest HIPEF conditions (35 kV/cm for 2,000 µs in bipolar mode). Bipolar mode pulses showed lower RALOX and RAPPO than monopolar mode. However, polarity did not show a significant effect on ∆E*. LOX was always more resistant to HIPEF treatment than PPO. The optimization process (26.35 kV/cm for 1,235 μs in bipolar mode) showed around 60% of enzyme inactivation and ∆E* = 0.69. Thermally processed broccoli juice exhibited the greatest color difference (∆E* = 7.89). HIPEF processing could be an appropriate technology to preserve the color properties and reduce the enzyme activity of broccoli juice. Practical applications Vegetable juices, in particular broccoli juice is attracting the food industry attention because it contains high amounts of nutrients; however, this fact increase their susceptibility to endogenous enzymes. HIPEF is a nonthermal technology for liquid food preservation that inactivates microorganisms and enzymes without compromising the nutritional and sensorial features of foods. Consequently, this technology could be used in the food industry as an alternative for thermal treatment to inactivate deteriorative enzymes in vegetable juices, offering to consumers a high quality product.

Extraction and structural characterization of collagen from fishbone by high intensity pulsed electric fields

AbstractCollagen was extracted from fishbone by high intensity pulsed electric fields (PEF) and its structure was characterized. A maximum collagen yield of 16.13 mg/mL was achieved under the following conditions: pepsin dosage of 1%, material‐liquid ratio of 1:10, electric field strength of 20 kV/cm, and pulse number of 8. The change of each secondary structure component content was highly correlated with the PEF operating parameters (R2 > .900). The tertiary structure of collagen was changed by PEF. The surface hydrophobicity increased first and then decreased with the PEF operating parameters. Scanning electron microscopy results showed the tissues changes of sample particles from dispersed and disorganized to uniform by PEF, but the high electric field strength (>30 kV/cm) and pulse number (>8) causes samples over agglomerated, which were dispersed disorderly. This article has proposed a new approach for comprehensive utilization of fishbone, which has important research significance for the promotion of PEF.Practical ApplicationsCollagen was extracted from fishbone by high intensity pulsed electric fields. The prepared fishbone collagen can be widely used in foods, cosmetics, biology, fertilizers, medical materials, and other fields. This article provides a new technique for comprehensive utilization of fishbone. The structure of extracted collagen was characterized. This opens up a new dimension in the study of the impact of PEF technology on protein structure.

Moderate intensity Pulsed Electric Fields (PEF) as alternative mild preservation technology for fruit juice

Moderate intensity Pulsed Electric Fields (PEF) was studied for microbial inactivation as an alternative to high intensity PEF or to classical thermal pasteurization. The process is characterized by the application of electric pulses, allowing an increase of the product temperature by the ohmic heat generated by the pulses. A systematic evaluation of the effect of parameters electric field strength (E) and pulse width (τ) on the inactivation of Escherichia coli, Listeria monocytogenes, Lactobacillus plantarum, Salmonella Senftenberg and Saccharomyces cerevisiae in orange juice was carried out in a continuous flow system. A wide range of conditions was evaluated, and both E and τ were shown to be important in the efficacy to inactivate micro-organisms. Remarkably, PEF conditions at E = 2.7 kV/cm and τ = 15–1000 μs showed to be more effective in microbial inactivation than at E = 10 kV/cm and τ = 2 μs.Inactivation kinetics of the tested PEF conditions were compared to an equivalent thermal process to disentangle non-thermal effects (electroporation) from thermal effects responsible for the microbial inactivation. At standard high intensity PEF treatment a non-thermal inactivation at E = 20 kV/cm and τ = 2 μs pulses was observed and attributed to electroporation. Non-thermal effects could also be resolved with moderate intensity PEF at E = 2.7 kV/cm and pulse width between τ = 15–1000 μs. Microbial inactivation at these moderate intensity PEF conditions was studied in more detail at different pH and medium conductivity for E. coli and L. monocytogenes in watermelon juice and coconut water. Under moderate intensity PEF conditions the effectiveness of treatment was independent of pH for all evaluated matrices in the pH range of 3.8–6.0, whereas under high intensity PEF conditions the pH of the product is a critical factor for microbial inactivation. This suggests that the inactivation proceeds through a different mechanism at moderate intensity PEF, and speculations for this mechanism are presented. In conclusion, moderate intensity PEF conditions at E = 2.7 kV/cm and pulse width of 15–1000 μs has potential for industrial processing for the preservation of fruit juices and pH neutral liquid food products.

Comparing the impact of high pressure, pulsed electric field and thermal pasteurization on quality attributes of cloudy apple juice using targeted and untargeted analyses

Abstract The impact of low-oxygen spiral-filter press technology combined with thermal pasteurization (TP), pulsed electric field (PEF) and high pressure processing (HPP) on cloudy apple juice quality was investigated immediately after the treatments and after 3 weeks of storage at 4 °C. Based on equivalent levels of microbial safety and desired shelf-life, low and high processing intensities were selected: TP (72 °C/15 s; 85 °C/30 s), PEF (12.5 kV/cm, 76.4 kJ/L; 12.3 kV/cm, 132.5 kJ/L), and HPP (400 MPa/3 min; 600 MPa/3 min). High intensity thermal treatment resulted in a bright, yellowish color which was maintained during storage. PPO and POD activities were largely reduced by high intensity PEF and TP yet showed high resistance to HPP. The highest vitamin C content was provided by fresh juice followed by PEF-treated juices. Due to oxidative degradation reactions, vitamin C of all treated samples significantly decreased during storage. Immediately after processing, high cloud stability values were obtained in all samples; however, cloud stability decreased during storage particularly for HPP juices with high residual PME. No significant changes were observed in pH, titratable acidity, organic acid and sugar content which also corresponded to sweet and sour taste. Results from untargeted volatile profiles showed that esters increased after PEF and were better retained after HPP. Contrary to TP treatment where ester degradation reactions occurred together with the formation of off-flavors. Most of the volatiles decreased during storage which could be linked to oxidation and ester hydrolysis reactions. Industrial relevance Being one of the most popular fruit juices consumed worldwide, cloudy apple juice can still undergo quality changes such as color degradation, cloud loss (fast sedimentation) and flavor changes during processing and storage. This study evaluates the potential of low-oxygen spiral-filter press in combination with different preservation technologies to obtain a maximal quality of cloudy apple juice. Results showed that high intensity thermal pasteurization can effectively inactivate quality-degrading enzymes, therefore it is useful to obtain an optimal cloudy apple juice product in terms of color and cloud stability. Although HPP has minimal impact on aroma of the juice, shelf-life of the juice may be limited due to incomplete enzyme inactivation. In the case of PEF treatment, thermal effects may contribute to maintain apple juice quality.

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 < 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.