Enhancing Cutin Extraction Efficiency from Industrially Derived Tomato Processing Residues by High-Pressure Homogenization.

This study primarily aimed to enhance the extraction of cutin from industrial tomato peel residues. Initially, the conventional extraction process was optimized using response surface methodology (RSM). Subsequently, high-pressure homogenization (HPH) was introduced to improve extraction efficiency and sustainability. The optimization process focused on determining the optimal conditions for conventional extraction via chemical hydrolysis, including temperature (100-130 °C), time (15-120 min), and NaOH concentration (1-3%). The optimized conditions, determined as 130 °C, 120 min, and 3% NaOH solution, yielded a maximum cutin extraction of 32.5%. Furthermore, the results indicated that applying HPH pre-treatment to tomato peels before alkaline hydrolysis significantly increased the cutin extraction yield, reaching 46.1%. This represents an approximately 42% increase compared to the conventional process. Importantly, HPH pre-treatment enabled cutin extraction under milder conditions using a 2% NaOH solution, reducing NaOH usage by 33%, while still achieving a substantial cutin yield of 45.6%. FT-IR analysis confirmed that cutin obtained via both conventional and HPH-assisted extraction exhibited similar chemical structures, indicating that the main chemical groups and structure of cutin remained unaltered by HPH treatment. Furthermore, cutin extracts from both conventional and HPH-assisted extraction demonstrated thermal stability up to approximately 200 °C, with less than 5% weight loss according to TGA analysis. These findings underscore the potential of HPH technology to significantly enhance cutin extraction yield from tomato peel residues while utilizing milder chemical hydrolysis conditions, thereby promoting a more sustainable and efficient cutin extraction process.

Sustainable Valorization of Industrial Cherry Pomace: A Novel Cascade Approach Using Pulsed Electric Fields and Ultrasound Assisted-Extraction.

In this study, a two-stage cascade extraction process utilizing pulsed electric fields (PEF) (3 kV/cm, 10 kJ/kg) for initial extraction, followed by ultrasound (US) (200 W, 20 min)-assisted extraction (UAE) in a 50% (v/v) ethanol-water mixture (T = 50 °C, t = 60 min), was designed for the efficient release of valuable intracellular compounds from industrial cherry pomace. The extracted compounds were evaluated for total phenolic content (TPC), flavonoid content (FC), total anthocyanin content (TAC), and antioxidant activity (FRAP), and were compared with conventional solid-liquid extraction (SLE). Results showed that the highest release of bioactive compounds occurred in the first stage, which was attributed to the impact of PEF pre-treatment, resulting in significant increases in TPC (79%), FC (79%), TAC (83%), and FRAP values (80%) of the total content observed in the post-cascade PEF-UAE process. The integration of UAE into the cascade process further augmented the extraction efficiency, yielding 21%, 49%, 56%, and 26% increases for TPC, FC, TAC, and FRAP, respectively, as compared to extracts obtained through a second-stage conventional SLE. HPLC analysis identified neochlorogenic acid, 4-p-coumaroylquinic, and cyanidin-3-O-rutinoside as the predominant phenolic compounds in both untreated and cascade-treated cherry pomace extracts, and no degradation of the specific compounds occurred upon PEF and US application. SEM analysis revealed microstructural changes in cherry pomace induced by PEF and UAE treatments, enhancing the porosity and facilitating the extraction process. The study suggests the efficiency of the proposed cascade PEF-UAE extraction approach for phenolic compounds from industrial cherry pomace with potential applications to other plant-based biomasses.

Pulsed electric fields-assisted extraction of valuable compounds from red grape pomace: Process optimization using response surface methodology.

Background: The application of Pulsed electric fields as a mild and easily scalable electrotechnology represents an effective approach to selectively intensify the extractability of bioactive compounds from grape pomace, one of the most abundant residues generated during the winemaking process. Objective: This study addressed the optimization of the pulsed electric fields (PEF)-assisted extraction to enhance the extraction yields of bioactive compounds from red grape pomace using response surface methodology (RSM). Methods: The cell disintegration index (Z p ) was identified as response variable to determine the optimal PEF processing conditions in terms of field strength (E = 0.5-5 kV/cm) and energy input (WT = 1-20 kJ/kg). For the solid-liquid extraction (SLE) process the effects of temperature (20-50°C), time (30-300min), and solvent concentration (0-50% ethanol in water) on total phenolic content (TPC), flavonoid content (FC), total anthocyanin content (TAC), tannin content (TC), and antioxidant activity (FRAP) of the extracts from untreated and PEF-treated plant tissues were assessed. The phenolic composition of the obtained extracts was determined via HPLC-PDA. Results: Results demonstrated that the application of PEF at the optimal processing conditions (E = 4.6 kV/cm, WT = 20 kJ/kg) significantly enhanced the permeabilization degree of cell membrane of grape pomace tissues, thus intensifying the subsequent extractability of TPC (15%), FC (60%), TAC (23%), TC (42%), and FRAP values (31%) concerning the control extraction. HPLC-PDA analyses showed that, regardless of the application of PEF, the most abundant phenolic compounds were epicatechin, p-coumaric acid, and peonidin 3-O-glucoside, and no degradation of the specific compounds occurred upon PEF application. Conclusion: The optimization of the PEF-assisted extraction process allowed to significantly enhance the extraction yields of high-value-added compounds from red grape pomace, supporting further investigations of this process at a larger scale.

Evaluating the influence of operational parameters of pulsed light on wine related yeasts: focus on inter- and intra-specific variability sensitivity.

In oenology, there is a growing demand by consumers for wines produced with less inputs (such as sulphite, frequently used for microbial control). Emerging control methods for managing microorganisms in wine are widely studied. In this study, the efficiency of pulsed light (PL) treatment was investigated. A drop-platted system was used to evaluate the impact of three PL operational parameters: the fluence per flash, the total fluence and the flash frequency. Fluence per flash appeared to be a key parameter prior to total fluence, thus demonstrating the importance of the effect of peak voltage during PL treatments. The efficiency of PL treatment was assessed on 198 strains distributed amongst fourteen yeast species related to wine environment, and an important variability in PL response was observed. Brettanomyces bruxellensis strains were strongly sensitive to PL, with intraspecific variation. PL was then applied to red wines inoculated with 9 strains of B. bruxellensis, Saccharomyces cerevisiae and Lachancea thermotolerans. Results confirmed interspecific response variability and a higher sensitivity of B. bruxellensis species to PL. Wine treatments with a total fluence of 22.8 J cm-2 resulted in more than 6 log reduction for different B. bruxellensis strains. These results highlight the potential of PL for wine microbial stabilization.

Antioxidant and Anti-Inflammatory Effects of Extracts from Pulsed Electric Field-Treated Artichoke By-Products in Lipopolysaccharide-Stimulated Human THP-1 Macrophages.

In this study, pulsed electric field (PEF-3 kV/cm; 5 kJ/kg) pretreatment was used to intensify the extractability of valuable intracellular compounds from artichoke by-products during a subsequent aqueous extraction (solid-liquid ratio = 1:10 g/mL, T = 20 °C; t = 120 min). Total phenolic content (TPC), antioxidant activity (DPPH, ABTS) and HPLC-PDA analysis of the artichoke extract (AE) and the biological effects on human cell lines were determined. Chlorogenic acid was found to be the most abundant phenolic compound (53% of the TPC) in the AE. The extract showed good antioxidant properties in a concentration-dependent manner. The potential biological effects of AE were investigated using THP-1 macrophages stimulated by lipopolysaccharides (LPS) as an in vitro model system of oxidative stress. Reduced reactive oxygen species production upon treatment with AE was found. Moreover, AE was able to reduce the secretion of the pro-inflammatory mediators Interleukin-6 and Monocyte Chemoattractant Protein-1 in LPS-stimulated macrophages, as determined by qRT-PCR and ELISA assays. These results highlighted the anti-inflammatory and antioxidant properties of the extracts from PEF-treated artichoke by-products, corroborating their potential application as a source of functional ingredients obtained through a feasible and sustainable process.

Application of Pulsed Electric Fields and High-Pressure Homogenization in Biorefinery Cascade of C. vulgaris Microalgae.

In this study, a cascaded cell disintegration process, based on pulsed electric fields (PEF - 20 kV/cm, 100 kJ/kgSUSP.) and high-pressure homogenization (HPH - 150 MPa, 5 passes) was designed for the efficient and selective release of intracellular compounds (water-soluble proteins, carbohydrates, and lipids) from C. vulgaris suspensions during extraction in water (25 °C, 1 h) and ethyl acetate (25 °C, 3 h). Recovery yields of target compounds from cascaded treatments (PEF + HPH) were compared with those observed when applying PEF and HPH treatments individually. Particle size distribution and scanning electron microscopy analyses showed that PEF treatment alone did not induce any measurable effect on cell shape/structure, whereas HPH caused complete cell fragmentation and debris formation, with an undifferentiated release of intracellular matter. Spectra measurements demonstrated that, in comparison with HPH alone, cascaded treatments increased the selectivity of extraction and improved the yields of carbohydrates and lipids, while higher yields of water-soluble proteins were measured for HPH alone. This work, therefore, demonstrates the feasibility of sequentially applying PEF and HPH treatments in the biorefinery of microalgae, projecting a beneficial impact in terms of process economics due to the potential reduction of the energy requirements for separation/purification stages.

Guidelines on reporting treatment conditions for emerging technologies in food processing.

In the last decades, different non-thermal and thermal technologies have been developed for food processing. However, in many cases, it is not clear which experimental parameters must be reported to guarantee the experiments' reproducibility and provide the food industry a straightforward way to scale-up these technologies. Since reproducibility is one of the most important science features, the current work aims to improve the reproducibility of studies on emerging technologies for food processing by providing guidelines on reporting treatment conditions of thermal and non-thermal technologies. Infrared heating, microwave heating, ohmic heating and radiofrequency heating are addressed as advanced thermal technologies and isostatic high pressure, ultra-high-pressure homogenization sterilization, high-pressure homogenization, microfluidization, irradiation, plasma technologies, power ultrasound, pressure change technology, pulsed electric fields, pulsed light and supercritical CO2 are approached as non-thermal technologies. Finally, growing points and perspectives are highlighted.

A Comprehensive Overview of Tomato Processing By-Product Valorization by Conventional Methods versus Emerging Technologies.

The tomato processing industry can be considered one of the most widespread food manufacturing industries all over the world, annually generating considerable quantities of residue and determining disposal issues associated not only with the wasting of invaluable resources but also with the rise of significant environmental burdens. In this regard, previous studies have widely ascertained that tomato by-products are still rich in valuable compounds, which, once recovered, could be utilized in different industrial sectors. Currently, conventional solvent extraction is the most widely used method for the recovery of these compounds from tomato pomace. Nevertheless, several well-known drawbacks derive from this process, including the use of large quantities of solvents and the difficulties of utilizing the residual biomass. To overcome these limitations, the recent advances in extraction techniques, including the modification of the process configuration and the use of complementary novel methods to modify or destroy vegetable cells, have greatly and effectively influenced the recovery of different compounds from plant matrices. This review contributes a comprehensive overview on the valorization of tomato processing by-products with a specific focus on the use of "green technologies", including high-pressure homogenization (HPH), pulsed electric fields (PEF), supercritical fluid (SFE-CO2), ultrasounds (UAE), and microwaves (MAE), suitable to enhancing the extractability of target compounds while reducing the solvent requirement and shortening the extraction time. The effects of conventional processes and the application of green technologies are critically analyzed, and their effectiveness on the recovery of lycopene, polyphenols, cutin, pectin, oil, and proteins from tomato residues is discussed, focusing on their strengths, drawbacks, and critical factors that contribute to maximizing the extraction yields of the target compounds. Moreover, to follow the "near zero discharge concept", the utilization of a cascade approach to recover different valuable compounds and the exploitation of the residual biomass for biogas generation are also pointed out.

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

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

Pulsed Electric Field-Assisted Extraction of Aroma and Bioactive Compounds From Aromatic Plants and Food By-Products.

In this work, the effect of pulsed electric field (PEF) pre-treatment on the extractability in green solvents (i. e., ethanol-water mixture and propylene glycol) of target aroma and bioactive compounds, such as vanillin from vanilla pods, theobromine and caffeine from cocoa bean shells, linalool from vermouth mixture, and limonene from orange peels, was investigated. The effectiveness of PEF as a cell disintegration technique in a wide range of field strength (1-5 kV/cm) and energy input (1-40 kJ/kg) was confirmed using impedance measurements, and results were used to define the optimal PEF conditions for the pre-treatment of each plant tissue before the subsequent solid-liquid extraction process. The extracted compounds from untreated and PEF-treated samples were analyzed via GC-MS and HPLC-PDA analysis. Results revealed that the maximum cell disintegration index was detected for cocoa bean shells and vanilla pods (Z p = 0.82), followed by vermouth mixture (Z p = 0.77), and orange peels (Z p = 0.55). As a result, PEF pre-treatment significantly enhanced the extraction yield of the target compounds in both solvents, but especially in ethanolic extracts of vanillin (+14%), theobromine (+25%), caffeine (+34%), linalool (+114%), and limonene (+33%), as compared with untreated samples. Moreover, GC-MS and HPLC-PDA analyses revealed no evidence of degradation of individual compounds due to PEF application. The results obtained in this work suggest that the application of PEF treatment before solid-liquid extraction with green solvents could represent a sustainable approach for the recovery of clean labels and natural compounds from aromatic plants and food by-products.

Pulsed Electric Fields-Assisted Extraction of Valuable Compounds From Arthrospira Platensis: Effect of Pulse Polarity and Mild Heating.

The present study aimed to investigate the effect of the main pulsed electric field (PEF) process parameters on the cell damages of A. platensis microalgae and the extractability of valuable compounds [water-soluble proteins (WSP), C-phycocyanin (C-PC), and carbohydrates (CH)]. Aqueous microalgae suspensions (2%, w/w) were PEF-treated at variable field strength (E = 10, 20, 30 kV/cm), total specific energy (W T = 20, 60, 100 kJ/kgsusp), and inlet temperature (25, 35, 45°C), with either monopolar or bipolar square wave pulses (5 µs of width, delay time between pulses of opposite polarities = 1, 5, 10, 20 µs), prior to extraction with water at room temperature (25°C) for up to 3 h. High-pressure homogenization (HPH) treatment (P = 150 MPa, 3 passes) was used to achieve complete cell disruption to quantify the total extractable content of target intracellular compounds. Scanning electron microscopy (SEM) and optical microscopy analyses clearly showed that PEF merely electroporated the membranes of algae cell, without damaging the cell structure and forming cell debris. The application of PEF treatment (monopolar pulses, 20 kV/cm and 100 kJ/kgsusp) at room temperature significantly enhanced the extraction yield of WSP [17.4% dry weight (DW)], CH (10.1% DW), and C-PC (2.1% DW), in comparison with the untreated samples. Bipolar pulses appeared less effective than monopolar pulses and led to extraction yields dependent on the delay time. Additionally, regardless of pulse polarity, a clear synergistic effect of the combined PEF (20 kV/cm and 100 kJ/kgsusp)-temperature (35°C) treatment was detected, which enabled the extraction of up to 37.4% (w/w) of total WSP, 73.8% of total CH, and 73.7% of total C-PC. Remarkably, the PEF treatment enabled to obtain C-phycocyanin extract with higher purity than that obtained using HPH treatment. The results obtained in this work suggest that the application of PEF combined with mild heating could represent a suitable approach for the efficient recovery of water-soluble compounds microalgal biomass.

High Voltage Electrical Discharges as an Alternative Extraction Process of Phenolic and Volatile Compounds from Wild Thyme (Thymus serpyllum L.): In Silico and Experimental Approaches for Solubility Assessment.

The objective of this study was to evaluate the potential of green solvents for extractions of bioactive compounds (BACs) and essential oils from wild thyme (Thymus serpyllum L.) using theoretical and experimental procedures. Theoretical prediction was assessed by Hansen solubility parameters (HSPs) and conductor-like screening model for realistic solvents (COSMO-RS), to predict the most suitable solvents for extraction of BACs. An experimental procedure was performed by nonthermal technology high voltage electrical discharge (HVED) and it was compared with modified conventional extraction (CE). Obtained extracts were analyzed for chemical and physical changes during the treatment. Theoretical results for solution of BACs in ethanol and water, as green solvents, were confirmed by experimental results, while more accurate data was given by COSMO-RS assessment than HSPs. Results confirmed high potential of HVED for extraction of BACs and volatile compounds from wild thyme, in average, 2.03 times higher yield of extraction in terms of total phenolic content was found compared to CE. The main phenolic compound found in wild thyme extracts was rosmarinic acid, while the predominant volatile compound was carvacrol. Obtained extracts are considered safe and high-quality source reach in BACs that could be further used in functional food production.

Decontamination of fresh-cut cucumber slices by a combination of a modified chitosan coating containing carvacrol nanoemulsions and pulsed light.

In this study, the impact of the combination of pulsed light (PL) treatments with antimicrobial coatings, consisting of modified chitosan suspensions incorporating carvacrol nanoemulsions, was investigated on the decontamination of fresh-cut cucumber slices. The upper surface of the cucumber slices, with or without the coating deposition, was inoculated with Escherichia coli ATCC 26 to reach a final concentration of 107CFU/g of the vegetable. PL treatments were conducted at different fluence (4, 8, and 12J/cm2) on the inoculated surface of cucumber slices. Results showed that the microbial reduction was only marginally affected by the coating formulation. A slight increase was observed when the carvacrol nanoemulsions were embedded in the chitosan matrix, but microbial reduction levels remained always below 1log cycle. In contrast, the different PL treatments resulted in a statistically significant increase in inactivation with increasing the treatment fluence, reaching 2.6log cycles at the maximum fluence. Remarkably, the combination of the antimicrobial coating with the most intense PL treatments resulted in a strong synergistic effect. For example, by combining a PL treatment at 12J/cm2 with one of the antimicrobial coatings a microbial reduction >5log cycles was reached. Therefore, it can be concluded that the combination of antimicrobial coatings and PL treatment is a promising method for surface decontamination of fresh-cut vegetables, which could be exploited in view of ensuring their microbiological safety.

Influence of pulsed light treatment on the aggregation of whey protein isolate.

The effect of pulsed light (PL) on the aggregation of whey protein isolate (WPI) solutions was investigated. PL fluence values from 4 to 16J/cm2 were used to treat WPI (1% w/v) solutions in sodium phosphate buffer (pH=7.5). Whey protein structural modification and aggregation were assessed through the determination of free SH-groups and UV-absorption spectra. Additionally, covalent and non-covalently linked protein-protein interactions were identified through the measurement of turbidity, aggregation index, particle size distribution, and SDS-PAGE. WPI upon PL treatment showed structural changes as demonstrated by the immediate increase of free SH-group content (unfolding) and the subsequent formation of a small fraction of aggregation of unfolded proteins, due to both hydrophobic interactions and the formation of disulphide bonds. Turbidity, mean particle size, and aggregation index increased in samples treated at PL fluence from 4 to 16J/cm2. Furthermore, particle size distribution analysis of samples treated at higher fluence indicated that WPI dimer dissociation and formation of larger particles were likely to occur. The association of intermediate and larger protein molecules as well as the formation of soluble aggregates between ß-lactoglobulin and α-lactalbumin were also observed in gel electrophoresis analysis. In conclusion, the results of this investigation demonstrated the potential of PL treatments to induce protein denaturation, with a minimal formation of soluble protein aggregates.

Innovative Alternative Technologies to Extract Carotenoids from Microalgae and Seaweeds.

Marine microalgae and seaweeds (microalgae) represent a sustainable source of various bioactive natural carotenoids, including ß-carotene, lutein, astaxanthin, zeaxanthin, violaxanthin and fucoxanthin. Recently, the large-scale production of carotenoids from algal sources has gained significant interest with respect to commercial and industrial applications for health, nutrition, and cosmetic applications. Although conventional processing technologies, based on solvent extraction, offer a simple approach to isolating carotenoids, they suffer several, inherent limitations, including low efficiency (extraction yield), selectivity (purity), high solvent consumption, and long treatment times, which have led to advancements in the search for innovative extraction technologies. This comprehensive review summarizes the recent trends in the extraction of carotenoids from microalgae and seaweeds through the assistance of different innovative techniques, such as pulsed electric fields, liquid pressurization, supercritical fluids, subcritical fluids, microwaves, ultrasounds, and high-pressure homogenization. In particular, the review critically analyzes technologies, characteristics, advantages, and shortcomings of the different innovative processes, highlighting the differences in terms of yield, selectivity, and economic and environmental sustainability.

Energy-efficient biomass processing with pulsed electric fields for bioeconomy and sustainable development.

Fossil resources-free sustainable development can be achieved through a transition to bioeconomy, an economy based on sustainable biomass-derived food, feed, chemicals, materials, and fuels. However, the transition to bioeconomy requires development of new energy-efficient technologies and processes to manipulate biomass feed stocks and their conversion into useful products, a collective term for which is biorefinery. One of the technological platforms that will enable various pathways of biomass conversion is based on pulsed electric fields applications (PEF). Energy efficiency of PEF treatment is achieved by specific increase of cell membrane permeability, a phenomenon known as membrane electroporation. Here, we review the opportunities that PEF and electroporation provide for the development of sustainable biorefineries. We describe the use of PEF treatment in biomass engineering, drying, deconstruction, extraction of phytochemicals, improvement of fermentations, and biogas production. These applications show the potential of PEF and consequent membrane electroporation to enable the bioeconomy and sustainable development.

Effect of pulsed electric fields - assisted extraction on anti-inflammatory and cytotoxic activity of brown rice bioactive compounds.

The bioactive compounds of brown rice exhibit many beneficial health effects, ranging from antioxidant to cytotoxic activities. Pulsed Electric Field (PEF) pretreatment can significantly enhance their extraction, through the induction of the electro-permeabilization of the cell membranes. This paper aims to demonstrate that PEF-assisted extraction of brown rice enables not only enhanced yields of antioxidant compounds, such as γ-oryzanol, polyphenols and phenolic acids, and of saturated and unsaturated fatty acids, but also increased cytotoxic effects on cancer cells. Initially, the PEF-assisted extraction conditions have been defined by the assessment of the cell permeabilization index via impedance measurements and the DPPH antioxidant activity. Subsequently, the biological effects of PEF have been evaluated on the cytotoxicity and anti-inflammatory properties against human colon cancer cell line HT29. The results show that PEF-assisted extraction, enhancing the yield of bioactive compounds, with respect to untreated extracts, significantly promotes their antioxidant activity, which is correlated with an increased HT29 cells cytotoxicity. In addition, PEF extracts of brown rice substantially inhibit also gene expression and interleukin production in colon cancer cells, suggesting their exploitation as natural anti-inflammatory agents. The integration of PEF pretreatment in the solvent extraction process of bioactives from brown rice appears, therefore, as a promising practice to significantly enhance their biological activity.

Effect of pulsed light treatment on structural and functional properties of whey protein isolate.

This work aimed at investigating the effects of Pulsed Light (PL) processing at different fluences (from 4 to 16J/cm2) on the structure and functional properties of Whey Protein Isolate (WPI) solution. The determination of the free and total sulfhydryl (SH) groups was used to detect the variation of WPI tertiary and quaternary structure. Additionally, PL-induced changes in secondary structure were determined by FT-IR spectroscopy and the differential scanning calorimetry (DSC), and primary structure by carbonyl content. The experimental data demonstrated that PL treatments increased the concentration of total and free sulfhydryl groups and protein carbonyls. A decrease of the denaturation temperature and enthalpy ratio with increasing the intensity of PL treatments was observed in DSC measurements. Small but significant changes in the secondary structure of PL treated WPI solution were also taking place and detected. The extent of whey protein structure modifications was fluence dependent. The results of this investigation demonstrated the potential of PL treatments to induce dissociation and partial unfolding of WPI, thus improving some of their functional properties, such as solubility and foaming ability.

Application of pulsed electric field in the production of juice and extraction of bioactive compounds from blueberry fruits and their by-products.

The influence of Pulsed Electric Field (PEF) pre-treatment of blueberry fruits (Vaccinium myrtillus L.), both on the extraction yield and antioxidant properties of juice obtained by pressing and on the on the recovery of bioactive compounds from berry by-products (press cake) by extraction with solvent, was investigated. PEF treatments carried out at field strengths of 1, 3, and 5 kV/cm and an energy input of 10 kJ/kg achieved a cell disintegration index (Z p ) of 0.70, 0.80, and 0.87, respectively. Mechanical pressing (1.32 bar for 8 min) of PEF-treated berries (1, 3, and 5 kV/cm at 10 kJ/kg) significantly increased the juice yield (+28 %) compared with the untreated sample. The juice obtained from PEF pre-treated berries also had a significantly higher total phenolic content (+43 %), total anthocyanin content (+60 %) and antioxidant activity (+31 %). However, PEF treatment intensity higher than 1 kV/cm did not significantly improve the quantitative or qualitative characteristics of the juice. Compared to the untreated sample, higher amounts of total phenolics (+63 %), total athocyanins (+78 %) and antioxidant activity (+65 %) were detected in the press cake extracts. PEF treatment of higher intensity resulted in better extractability of bioactive compounds from blueberry press cake. The results obtained from this study demonstrate the potential of PEF as a mild pre-treatment method to improve the efficiency of the industrial processing of berry fruits.

Pulsed electric field-assisted vinification of aglianico and piedirosso grapes.

Pulsed electric field (PEF) treatments were applied to increase the polyphenolic content of fresh red wines made from Aglianico and Piedirosso grapes. Prior to the fermentation/maceration step, the grape skins were treated at different PEF intensities (field strengths from 0.5 to 1.5 kV/cm and energy inputs from 1 to 50 kJ/kg), with their permeabilization being characterized by electrical impedance measurements. Furthermore, the release kinetics of the total polyphenols and anthocyanins were characterized during the maceration stage by spectroscopic and Folin-Ciocalteu colorimetric methods, respectively. Finally, the fresh wine, obtained after pressing, was characterized for total acidity, pH, reducing sugar, color intensity, total polyphenols, anthocyanins content, antioxidant activity, and volatile compound composition. PEF treatment on Aglianico grapes induced a significantly higher release of polyphenols (+20%) and anthocyanins (+75%), thus improving the color intensity (+20%) and the antioxidant activity of the wine (+20%) while preserving the other organoleptic characteristics. In contrast, there was only a minor impact on the polyphenolic release kinetics of Piedirosso grapes, despite the significant degree of cell membrane permeabilization.