Comprehensive review on pulsed electric field in food preservation: gaps in current studies for potential future research

A Review of Non-thermal Interventions in Food Processing Technologies

Foodborne pathogens and spoilage microorganisms continue to be a concern throughout the food industry. As a result, these problematic microorganisms are the cause of foodborne outbreaks, foodborne illness, and premature spoilage-related issues. To address these, thermal technologies have been applied and have a documented history of controlling these microorganisms. Although beneficial, some of these technologies may result in adverse quality effects that can interfere with consumer acceptability. Processors of fresh produce also need technologies to mitigate pathogens with the ability to retain raw quality. In addition, thermal technologies can also result in the reduction or depletion of key nutrients. Consumers of today are health conscious and are concerned with key nutrients in food products necessary for their overall health; this reduction and depletion of nutrients could be considered unacceptable in the eyes of consumers. As a result of this, the food industry works to increase the use of nonthermal technologies to control pathogens and spoilage microorganisms in varying sections of the industry. This review paper will focus on the control of foodborne pathogens and spoilage organisms along with the effects on quality in various food products by the use of pulsed electric field, pulsed light, ultraviolet light, ozonation, cold atmospheric plasma, ultrasound, and ionizing radiation.

Quality Attributes, Structural Characteristics, and Functional Properties of Brewer's Spent Grain Protein Concentrates as Affected by Alkaline and Pulsed Electric Field-Assisted Extraction

The rising protein demand has driven intensified research into alternative protein sources and extraction technologies. Brewer's spent grain (BSG), which is rich in protein, remains mostly underutilized. This study aimed to optimize BSG protein extraction conditions using pulsed electric field (PEF) by assessing the influence of pulse numbers (5000-9000), electric field strength (8-10 kV/cm), and frequency (8-10 Hz) on protein recovery and purity. The optimized conditions (5386 pulses, 10 kV/cm field strength, and 10 Hz frequency) provided a higher extraction yield with a significant improvement of approximately 90% (p < 0.05). Essential amino acids in proteins extracted via PEF were significantly increased (60,864.84 mg/100 g), particularly phenylalanine, threonine, and valine; furthermore, amino acid score (AAS) and protein digestibility-corrected amino acid score (PDCAAS) were found to be superior to those of protein obtained through alkaline extraction. The PEF treatment resulted in the modification of the secondary structures of proteins from α-helices and β-turns to β-sheets, as well as the enhancement of the hydrophobic-hydrophilic amino acid balance. The functional properties of the proteins, particularly their foaming properties and solubility, were significantly affected by PEF (p < 0.05). In conclusion, PEF-assisted extraction produces high-quality BSG protein concentrates efficiently while rendering the process environmentally sustainable.

Clean Label Approaches in Cheese Production: Where Are We?

The Clean Label concept has gained significant traction in the cheese industry due to consumer preferences for minimally processed cheeses free from synthetic additives. This review explores different approaches for applying Clean Label principles to the cheese industry while maintaining food safety, sensory quality, and shelf life. Non-thermal technologies, such as high-pressure processing (HPP), pulsed electric fields (PEF), ultra-violet (UV), and visible light (VL), are among the most promising methods that effectively control microbial growth while preserving the nutritional and functional properties of cheese. Protective cultures, postbiotics, and bacteriophages represent microbiological strategies that are natural alternatives to conventional preservatives. Another efficient approach involves plant extracts, which contribute to microbial control, and enhance cheese functionality and potential health benefits. Edible coatings, either alone or combined with other methods, also show promising applications. Despite these advantages, several challenges persist: higher costs of production and technical limitations, possible shorter shelf-life, and regulatory challenges, such as the absence of standardized Clean Label definitions and compliance complexities. Further research is needed to develop and refine Clean Label formulations, especially regarding bioactive peptides, sustainable packaging, and advanced microbial control techniques. Addressing these challenges will be essential for expanding Clean Label cheese availability while ensuring product quality and maintaining consumer acceptance.

Non-Thermal Treatment Mediated by Curcumin for Enhancing Food Product Quality

Increasing antibiotic resistance is one of the world's greatest health problems, and biocide use in food disinfection, alongside other application fields, could increase antibiotic resistance. Effective and eco-friendly food decontamination treatment with minimal chemical intervention in food production is urgently needed. Synergistic antimicrobial interaction of photoactive compounds and blue-light-emitting diodes have recently been proven effective in agricultural and environmental applications. Curcumin-based non-thermal treatment has been reviewed in this work for the development of a safe and effective decontamination tool that could be adapted to the food industry. The antimicrobial mechanism of the synergistic interaction and the inhibitory efficacy against foodborne pathogens (bacteria in both vegetative form and spore, as well as in biofilms) are discussed. Further studies on curcumin and its derivative, as well as light illumination patterns, were compared for enhanced bactericidal efficacy. Moreover, studies relating to photodynamic inactivation treatment for food sanitation and food quality enhancement (cereal grains and other food products) were summarized, as well as the impact on food organoleptic and nutritional quality.

Impact of Metabolites from Foodborne Pathogens on Cancer

Foodborne pathogens are microorganisms that cause illness through contamination, presenting significant risks to public health and food safety. This review explores the metabolites produced by these pathogens, including toxins and secondary metabolites, and their implications for human health, particularly concerning cancer risk. We examine various pathogens such as Salmonella sp., Campylobacter sp., Escherichia coli, and Listeria monocytogenes, detailing the specific metabolites of concern and their carcinogenic mechanisms. This study discusses analytical techniques for detecting these metabolites, such as chromatography, spectrometry, and immunoassays, along with the challenges associated with their detection. This study covers effective control strategies, including food processing techniques, sanitation practices, regulatory measures, and emerging technologies in pathogen control. This manuscript considers the broader public health implications of pathogen metabolites, highlighting the importance of robust health policies, public awareness, and education. This review identifies research gaps and innovative approaches, recommending advancements in detection methods, preventive strategies, and policy improvements to better manage the risks associated with foodborne pathogens and their metabolites.

Pulsed electric field processing of edible insect slurries induces thermally-assisted microbial inactivation

Insect-based food ingredients are emerging as sustainable protein sources, but their production requires ensuring microbial safety and inactivation of endogenous enzymes to avoid undesirable proteolysis, without compromising protein structure. While traditional thermal processing affects the protein structure, the potential of pulsed electric field (PEF) technology to inactivate microorganisms in lesser mealworm and house cricket slurries at pH 3 while simultaneously retaining the native protein structure is yet unexplored. Lesser mealworm and house cricket slurries at pH 3 were subjected to continuous and batch PEF treatments with varying intensities (0-450 kJ/kg). Microbial inactivation (aerobes, anaerobes, yeasts, and moulds), temperature changes, protein solubility, protein structure (SDS-PAGE and FTIR), and endogenous protease activity were assessed. For both insect species, high-intensity PEF (>150 kJ/kg) achieved up to 5 log microbial reduction, but increased temperatures up to 75 °C, altering protein structure. Low-intensity PEF did not affect protein conformation and protease activity, but was not effective in microbial inactivation (<1 log reduction). We conclude that while PEF can effectively inactivate microorganisms, it cannot be considered a non-thermal method for the present sample conditions due to the temperature increase at higher intensities. PEF could be well-suitable for incorporation in hurdle techniques, such as combinations with moderate heating. Future research should investigate synergistic effects of PEF, also for using alternative PEF set-ups, with other mild processing techniques for effective microbial inactivation while preserving native protein structure. Furthermore, optimal PEF intensities for enhanced protein solubility should be explored.

Influence of crystalline properties on starch functionalization from the perspective of various physical modifications: A review

The relationship between structural properties and functional characteristics of starch remains a hot subject among researchers. The crystalline property is a substantial characteristic of starch granules, undergoing different changes during modification techniques. These changes are closely related to the functional properties of modified starches. Physical modifications are eco-friendly techniques and are widely adopted for starch modifications. Therefore, understanding the impact of changes in crystalline properties during different physical modifications on starch functionality is the ultimate way to improve their industrial utilization. However, the existing literature still lacks the elucidation of changes in functional properties of starch in accordance with its crystalline properties during different physical treatments. Hence, this review summarizes the effects of the most important and widely used physical modifications on starch crystalline properties, highlighting the alterations in various functional properties such as hydration, pasting, gelatinization, and in vitro digestibility resulting from changes in crystalline characteristics in a single comprehensive discussion. Furthermore, the current review gives direction for envisaging the functionalization of starches based on deviations in the crystalline properties during several physical treatments.

Comparison of microwave and pulsed electric field methods on extracting antioxidant compounds from Arvaneh plant (Hymenocrater platystegius Rech. F)

Improving the quality of extracts derived from medicinal plants is a critical concern due to their extensive use across various industries. The Arvaneh plant (Hymenocrater platystegius Rech. F), a species native to the Khorasan province in Iran and belonging to the mint family, was the focus of this study. We optimized the extraction of Arvaneh plant using both microwave (MW) and pulsed electric field (PEF) techniques. The MW method was tested at different processing times (90, 180, and 270 s) and power levels (180, 540, and 900 W), while the PEF method was evaluated with varying electric field intensities (0.25, 3.25, and 6.25 kV/cm) and pulse numbers (10, 45, and 80) using a central composite design (CCD). The results revealed that extraction efficiency, total phenolic content, and total flavonoid content were significantly higher with the PEF method compared to the MW method (p < 0.05). Moreover, the PEF technique showed superior performance in preserving the antioxidant properties of the extract, as assessed by DPPH and FRAP methods. GC/MS analysis confirmed the presence of 27 bioactive compounds in the Arvaneh extract obtained through PEF-assisted extraction. In conclusion, the PEF method proved to be highly efficient for extracting bioactive compounds from the Arvaneh plant.

Green and sustainable technologies for extraction of carotenoids from natural sources: a comprehensive review

In recent years, driven by increasing consumer demand for natural and healthy convenient foods, the food industry has been shifting from synthetic to natural products. This shift is also reflected in the growing popularity of non-conventional extraction methods for pigments, which are favored for sustainability and environment-friendliness compared to conventional processes. This review aims to investigate the extraction of carotenoids from a variety of natural sources, including marine sources like fungus, microalgae, and crustaceans, as well as widely studied plants like tomatoes and carrots. Additionally, it delves into the recovery of valuable carotenoids from waste products like pomace and peels, highlighting the nutritional and environmental benefits. The review also emphasizes the role of green solvents such limonene, vegetable oils, ionic liquids, supercritical fluids, and natural deep eutectic solvents in effective and ecologically friendly carotenoid extraction. These technologies support the ideas of a circular and sustainable economy in addition to having a smaller negative impact on the environment. Overall, the present study highlights the crucial importance of green extraction technologies in achieving the dual goals of sustainability and public safety.

Pulsed Electric Fields Effects on Proteins: Extraction, Structural Modification, and Enhancing Enzymatic Activity

Pulsed electric field (PEF) is an innovative physical method for food processing characterized by low energy consumption and short processing time. This technology represents a sustainable procedure to extend food shelf-life, enhance mass transfer, or modify food structure. The main mechanism of action of PEF for food processing is the increment of the permeability of the cell membranes by electroporation. However, it has also been shown that PEF may modify the technological and functional properties of proteins. Generating a high-intensity electric field necessitates the flow of an electric current that may have side effects such as electrochemical reactions and temperature increments due to the Joule effect that may affect food components such as proteins. This article presents a critical review of the knowledge on the extraction of proteins assisted by PEF and the impact of these treatments on protein composition, structure, and functionality. The required research for understanding what happens to a protein when it is under the action of a high-intensity electric field and to know if the mechanism of action of PEF on proteins is different from thermal or electrochemical effects is underlying.

Advancements in Pulse Starches: Exploring Non-Thermal Modification Methods

The surge in the global demand for plant-based proteins has catapulted pulse protein into the spotlight. To ensure economic viability and sustainable production, it is crucial to utilize pulse starch, a by-product of plant protein fractionation. Despite the increasing interest in pulse starches, there is a notable gap in knowledge regarding their modifications and applications compared to cereal and tuber starches. Non-thermal techniques such as electron beam radiation, static high pressure, microfluidization, and cold plasma are emerging as innovative methods for starch modification. These techniques offer significant advantages, including enhanced safety, environmental sustainability, and the development of unique functional properties unattainable through conventional methods. However, challenges such as equipment availability, high costs, and energy consumption hinder their widespread adoption. In light of the growing emphasis on "clean and green labelling" and effective "waste management" in food production, evaluating non-thermal techniques for pulse starch modification is critical. This review aims to thoroughly assess these non-thermal techniques and their combinations, offering valuable insights for researchers and the food industry. By maximizing the potential of pulse starches in innovative food applications, it provides a comprehensive guide for effective non-thermal methods that add value and align with sustainable practices.

Effects of PEF on Cell and Transcriptomic of Escherichia coli

Pulsed electric field (PEF) is an up-to-date non-thermal processing technology with a wide range of applications in the food industry. The inactivation effect of PEF on Escherichia coli was different under different conditions. The E. coli inactivated number was 1.13 ± 0.01 lg CFU/mL when PEF was treated for 60 min and treated with 0.24 kV/cm. The treatment times were found to be positively correlated with the inactivation effect of PEF, and the number of E. coli was reduced by 3.09 ± 0.01 lg CFU/mL after 100 min of treatment. The inactivation assays showed that E. coli was inactivated at electrical intensity (0.24 kV/cm) within 100 min, providing an effective inactivating outcome for Gram-negative bacteria. The purpose of this work was to investigate the cellular level (morphological destruction, intracellular macromolecule damage, intracellular enzyme inactivation) as well as the molecular level via transcriptome analysis. Field Emission Scanning Electron Microscopy (TFESEM) and Transmission Electron Microscope (TEM) results demonstrated that cell permeability was disrupted after PEF treatment. Entocytes, including proteins and DNA, were markedly reduced after PEF treatment. In addition, the activities of Pyruvate Kinase (PK), Succinate Dehydrogenase (SDH), and Adenosine Triphosphatase (ATPase) were inhibited remarkably for PEF-treated samples. Transcriptome sequencing results showed that differentially expressed genes (DEGs) related to the biosynthesis of the cell membrane, DNA replication and repair, energy metabolism, and mobility were significantly affected. In conclusion, membrane damage, energy metabolism disruption, and other pathways are important mechanisms of PEF's inhibitory effect on E. coli.

Biofungicides Based on Plant Extracts: On the Road to Organic Farming

Phytopathogenic fungi are responsible for diseases in commercially important crops and cause major supply problems in the global food chain. Plants were able to protect themselves from disease before humans played an active role in protecting plants. They are known to synthesize a variety of secondary metabolites (SMs), such as terpenes, alkaloids, and phenolic compounds, which can be extracted using conventional and unconventional techniques to formulate biofungicides; plant extracts have antifungal activity and various mechanisms of action against these organisms. In addition, they are considered non-phytotoxic and potentially effective in disease control. They are a sustainable and economically viable alternative for use in agriculture, which is why biofungicides are increasingly recognized as an attractive option to solve the problems caused by synthetic fungicides. Currently, organic farming continues to grow, highlighting the importance of developing environmentally friendly alternatives for crop production. This review provides a compilation of the literature on biosynthesis, mechanisms of action of secondary metabolites against phytopathogens, extraction techniques and formulation of biofungicides, biological activity of plant extracts on phytopathogenic fungi, regulation, advantages, disadvantages and an overview of the current use of biofungicides in agriculture.

Quality evaluation of house cricket flour processed by electrohydrodynamic drying and pulsed electric fields treatment

House crickets are expected to play a significant role in the future food sector. Electrohydrodynamic (EHD) drying offers an environmentally friendly alternative to conventional drying methods. Pulsed electric fields (PEF) is a non-thermal process that facilitates conventional processes. EHD was applied to house crickets with and without PEF pretreatment, and the effect of PEF and EHD on the quality of the insects was evaluated. PEF pretreatment positively affected the oven drying at 60 °C by reducing its duration and thus decreasing the energy consumption by 14.22%. Moisture removal of EHD was not sufficient to replace oven drying, but when combined with oven drying, the overall energy consumption was reduced by >50%. PEF processing also increased the protein solubility (53.07% higher than the respective control) and antioxidant activity (24.05% higher than the respective control) of the oven-dried samples and reduced the histamine content of the EHD-dried samples (25.87% lower than the respective control).

Pulsed electric field technology in vegetable and fruit juice processing: A review

The worldwide market for vegetable and fruit juices stands as a thriving sector with projected revenues reaching to $81.4 billion by 2024 and an anticipated annual growth rate of 5.27% until 2028. Juices offer a convenient means of consuming bioactive compounds and essential nutrients crucial for human health. However, conventional thermal treatments employed in the juice and beverage industry to inactivate spoilage and pathogenic microorganisms, as well as endogenous enzymes, can lead to the degradation of bioactive compounds and vitamins. In response, non-thermal technologies have emerged as promising alternatives to traditional heat processing, with pulsed electric field (PEF) technology standing out as an innovative and sustainable choice. In this context, this comprehensive review investigated the impact of PEF on the microbiological, physicochemical, functional, nutritional, and sensory qualities of vegetable and fruit juices. PEF induces electroporation phenomena in cell membranes, resulting in reversible or irreversible changes. Consequently, a detailed examination of the effects of PEF process variables on juice properties is essential. Monitoring factors such as electric field strength, frequency, pulse width, total treatment time, and specific energy is important to ensure the production of a safe and chemically/kinetically stable product. PEF technology proves effective in microbial and enzymatic inactivation within vegetable and fruit juices, mitigating factors contributing to deterioration while maintaining the physicochemical characteristics of these products. Furthermore, PEF treatment does not compromise the content of substances with functional, nutritional, and sensory properties, such as phenolic compounds and vitamins. When compared to alternative processing methods, such as mild thermal treatments and other non-thermal technologies, PEF treatment consistently demonstrates comparable outcomes in terms of physicochemical attributes, functional properties, nutritional quality, and overall safety.

The Effect of Low Temperature Storage on the Lipid Quality of Fish, Either Alone or Combined with Alternative Preservation Technologies

Marine foods are highly perishable products due to their high content of polyunsaturated fatty acids, which can be readily oxidized to form peroxides and secondary oxidation products, thus conferring such foods undesirable organoleptic characteristics and generating harmful compounds that are detrimental to the health of consumers. The use of preservation methods that minimize lipid oxidation is required in the fishing and aquaculture industries. Low temperature storage (chilling or freezing) is one of the most commonly used preservation methods for fish and seafood, although it has been shown that the oxidation of the lipid fraction of such products is partially but not completely inhibited at low temperatures. The extent of lipid oxidation depends on the species and the storage temperature and time, among other factors. This paper reviews the effect of low temperature storage on the lipid quality of fish, either alone or in combination with other preservation techniques. The use of antioxidant additives, high hydrostatic pressure, irradiation, ozonation, ultrasounds, pulsed electric fields, and the design of novel packaging can help preserve chilled or frozen fish products, although further research is needed to develop more efficient fish preservation processes from an economic, nutritional, sensory, and sustainable standpoint.

Electrical Fields in the Processing of Protein-Based Foods

Electric field-based technologies offer interesting perspectives which include controlled heat dissipation (via the ohmic heating effect) and the influence of electrical variables (e.g., electroporation). These factors collectively provide an opportunity to modify the functional and technological properties of numerous food proteins, including ones from emergent plant- and microbial-based sources. Currently, numerous scientific studies are underway, contributing to the emerging body of knowledge about the effects on protein properties. In this review, "Electric Field Processing" acknowledges the broader range of technologies that fall under the umbrella of using the direct passage of electrical current in food material, giving particular focus to the ones that are industrially implemented. The structural and biological effects of electric field processing (thermal and non-thermal) on protein fractions from various sources will be addressed. For a more comprehensive contextualization of the significance of these effects, both conventional and alternative protein sources, along with their respective ingredients, will be introduced initially.

Bioactive Components, Applications, Extractions, and Health Benefits of Winery By-Products from a Circular Bioeconomy Perspective: A Review

Significant waste streams produced during winemaking include winery by-products such as pomace, skins, leaves, stems, lees, and seeds. These waste by-products were frequently disposed of in the past, causing resource waste and environmental issues. However, interest has risen in valorizing vineyard by-products to tap into their latent potential and turn them into high-value products. Wine industry by-products serve as a potential economic interest, given that they are typically significant natural bioactive sources that may exhibit significant biological properties related to human wellness and health. This review emphasizes the significance of winery by-product valorization as a sustainable management resource and waste management method. The novelty of this review lies in its comprehensive analysis of the potential of winery by-products as a source of bioactive compounds, extraction techniques, health benefits, and applications in various sectors. Chemical components in winery by-products include bioactive substances, antioxidants, dietary fibers, organic acids, and proteins, all of which have important industrial and therapeutic applications. The bioactives from winery by-products act as antioxidant, antidiabetic, and anticancer agents that have proven potential health-promoting effects. Wineries can switch from a linear waste management pattern to a more sustainable and practical method by adopting a circular bioeconomy strategy. Consequently, the recovery of bioactive compounds that function as antioxidants and health-promoting agents could promote various industries concomitant within the circular economy.

Novel Efficient Physical Technologies for Enhancing Freeze Drying of Fruits and Vegetables: A Review

Drying is the main technical means of fruit and vegetable processing and storage; freeze drying is one of the best dehydration processes for fruit and vegetables, and the quality of the final product obtained is the highest. The process is carried out under vacuum and at low temperatures, which inhibits enzymatic activity and the growth and multiplication of micro-organisms, and better preserves the nutrient content and flavor of the product. Despite its many advantages, freeze drying consumes approximately four to ten times more energy than hot-air drying, and is more costly, so freeze drying can be assisted by means of highly efficient physical fields. This paper reviews the definition, principles and steps of freeze drying, and introduces the application mechanisms of several efficient physical fields such as ultrasonic, microwave, infrared radiation and pulsed electric fields, as well as the application of efficient physical fields in the freeze drying of fruits and vegetables. The application of high efficiency physical fields with freeze drying can improve drying kinetics, increase drying rates and maintain maximum product quality, providing benefits in terms of energy, time and cost. Efficient physical field and freeze drying technologies can be well linked to sustainable deep processing of fruit and vegetables and have a wide range of development prospects.