Non-thermal Food Processing Research Articles

Cold plasma technology: does it have a place in food processing?

In recent years, there has been a growing demand for alternative food processing technologies that can improve food safety while preserving the nutritional quality of food products. Traditional thermal processing methods can lead to nutrient loss and degradation, prompting the exploration of novel approaches. Cold plasma (CP) technology, an emerging non-thermal food processing technique, has gained significant attention for its potential in the food industry. We provide herein, an introduction to CP and an overview of the technology, highlighting its potential advantages in safety, efficiency, and environmental friendliness.

Advances in Non-thermal Food Processing Methods-Principle Advantages and Limitations for the Establishment of Minimal Food Quality as well as Safety Issues: A Review

Background: The demand from consumers for safe, healthy food with a long shelf life, with no change in taste or nutritive value, has made food safety a key concern in today's world. Traditional thermal food processing technology has trouble meeting these standards. Conventional thermal and non-thermal processing has limitations and to overcome these limitations more studies are conducted regarding the novel non-thermal food processing methods. Objective: The goal of this paper was to present an overview of the research on the development of non-thermal processing techniques, such as electrofreezing, high hydrostatic pressure, pulsed electric fields, ultrasound, pulsed light, and plasma activated water, as well as their advantages and limitations. Methods: The present review aims to summarize findings related to novel non-thermal processing techniques, gathered from work published in scientific journals, related books, and book chapters from sources such as Web of Science (WoS), Google Scholar, Scopus and ScienceDirect. Results: Non-thermal treatment may result in more desirable outcomes, such as greater preservation of heat-sensitive nutrients, fewer changes in sensorial as well as physico-chemical quality of the processed foods. Conclusion: Compared to traditional heat processing, the nutritional value of foods is better preserved, and the sensory qualities of foods are less altered. These novel techniques can be combined with each other to achieve higher efficiency and overcome other limitations. More studies should be conducted regarding the combination of novel non-thermal techniques to achieve greater efficiency.

How pulse electric field treatment affects anti-nutritional factors and plant protein digestibility: A concise review

Consumption of foods rich in anti-nutritional factors (ANFs) can lead to inadequate absorption of vitamins and minerals. Pulsed electric field (PEF) treatment is a non-thermal food processing technology that uses short bursts of high voltage electric fields to induce structural modifications in biomolecules, including proteins, through electrochemical reactions and polarization of structural moieties. PEF offers potential benefits in enhancing the nutritional quality of food products by altering the structure and function of ANFs. However, the effects of PEF on ANFs in food have not been well established. Additionally, PEF-treated samples may undergo protein structural orientation modification due to electroporation and free radical species, potentially unfolding the native structure and influencing protein digestibility. Moreover, by increasing the mass transfer rate, electroporation can enhance the extraction of the initially trapped fractions into the solvent medium, which may include target compounds that affect protein functionality and digestibility. However, the protein digestibility of PEF-treated food products is yet to be thoroughly explored. Therefore, this review objectively investigates the possible mechanisms involved and the effectiveness of PEF in reducing different ANFs and modifying plant protein digestibility. This review also provides in-depth information about the possible applications of PEF-treated food items in the food industry.

Consumer perception of risk towards new sustainable non-thermal food processing technologies: A cross-cultural study between Portugal, Germany, and the UK

Consumers are interested in sustainable and safe food with positive sensory attributes, either minimally processed or incorporating sustainable processes. However, the introduction of new food technologies may generate concern among consumers. This study aims to identify ways to decrease consumers' risk perception of new technologies: High pressure, Non-thermal Plasma, Pulsed Electric Field, and Ultrasound. This cross-cultural study was conducted in three contrasting countries: Portugal, Germany, and the United Kingdom, recruiting over 400 consumers per country. The survey presented twelve constructs based on the Ecological Framework, which was used to predict perceived risk. Factors affecting such perception varied both for technologies and countries, as shown by a multiple regression model. Food technology neophobia, perceived relative severity, and trust were common factors across all countries. This study demonstrates that developing and producing new products using non-thermal technologies should consider the country's consumers' risk perception factors.

Retraction: Hydrodynamic cavitation: a novel non-thermal liquid food processing technology

Retraction: Hydrodynamic cavitation: a novel non-thermal liquid food processing technology

Effects of pulsed electric field technology on the nutritional value and biological function of plant food

Pulsed Electric Fields (PEF) technology is an emerging non-thermal food processing technology that is widely used because of its low damage to food quality and its ability to kill harmful microorganisms in food. The oxidative stress caused by PEF results in the synthesis and accumulation of nutrients, and plant foods stimulated by PEF produce large amounts of Reactive Oxygen Species (ROS), which activate the metabolite synthesis pathway and eventually synthesize proteins, polyphenols, thioglucosides and carotenoids; ROS accumulate in the cell membrane of microorganisms and cause protein expression. The accumulation of ROS in the cell membrane of microorganisms can cause abnormal protein expression, damage the lipid layer and Deoxyribonucleic Acid (DNA), and eventually lead to microbial inactivation. PEF technology in food processing are multifaceted, enhancing both the nutritional value of food through the augmented presence of health-beneficial compounds and ensuring food safety by effectively inactivating harmful microorganisms. This innovative technology stands at the forefront of food processing solutions, promising to fulfill the growing consumer demand for foods that are not only safe and of high quality but also rich in nutritional value. PEF’s role as a cornerstone technology in the food industry heralds a new era of food processing, where nutrition and safety converge to meet the sophisticated needs of today’s consumers.

Possible interactions between selected food processing and medications.

The impact of food processing on drug absorption, metabolism, and subsequent pharmacological activity is a pressing yet insufficiently explored area of research. Overlooking food-processing-drug interactions can significantly disrupt optimal clinical patient management. The challenges extend beyond merely considering the type and timing of food ingestion as to drug uptake; the specific food processing methods applied play a pivotal role. This study delves into both selected thermal and non-thermal food processing techniques, investigating their potential interference with the established pharmacokinetics of medications. Within the realm of thermal processing, conventional methods like deep fat frying, grilling, or barbecuing not only reduce the enteric absorption of drugs but also may give rise to side-products such as acrylamide, aldehydes, oxysterols, and oxyphytosterols. When produced in elevated quantities, these compounds exhibit enterotoxic and pro-inflammatory effects, potentially impacting the metabolism of various medications. Of note, a variety of thermal processing is frequently adopted during the preparation of diverse traditional herbal medicines. Conversely, circumventing high heat through innovative approaches (e.g., high-pressure processing, pulsed electric fields, plasma technology), opens new avenues to improve food quality, efficiency, bioavailability, and sustainability. However, it is crucial to exercise caution to prevent the excessive uptake of active compounds in specific patient categories. The potential interactions between food processing methods and their consequences, whether beneficial or adverse, on drug interactions can pose health hazards in certain cases. Recognizing this knowledge gap underscores the urgency for intensified and targeted scientific inquiry into the multitude of conceivable interactions among food composition, processing methods, and pharmaceutical agents. A thorough investigation into the underlying mechanisms is imperative. The complexity of this field requires substantial scrutiny and collaborative efforts across diverse domains, including medicine, pharmacology, nutrition, food science, food technology, and food engineering.

Promoting the Aging Process and Enhancing the Production of Antioxidant Components of Garlic through Pulsed Electric Field Treatments.

Shortening the aging duration and enhancing the functional components of garlic present significant technical challenges that need to be addressed. Thus, this study aimed to evaluate the potential role of pulsed electric field (PEF) treatment, a novel nonthermal food processing method, in promoting and enhancing the functional attributes of aged garlic. Our results showed that 2-4 kV/cm PEF pretreatment increased S-allyl cysteine (SAC), total polyphenol (TPC), and flavonoid contents (TFC) compared with un-pretreated garlic during aging. The browning and texture-softening were also significantly improved during processing time, though the latter showed no significant difference from the eighth day to the end of the aging process. The principal component analysis results showed that PEF positively affects the SAC and TFC formations without adverse effects. Among the PEF pretreatments, 3 kV/cm is the most effective in enhancing functional component production compared with the other PEF pretreatments. Therefore, PEF pretreatment is a time-saving process that promotes and enhances the functionality of aged garlic.

Impact of High Pressure Processing on the Safety and Quality of Food Products: A Review.

High pressure processing (HPP) has become a practical food processing technique that meets the preferences of consumers seeking lightly processed, convenient, and fresh-tasting food options. This paper reviewed the latest research on the impact HPP on the safety and quality of food products. The use of HPP has been showing favorable growth in the food industry primarily due to its potential to not only enhance the nutritional content and sensory attributes of food products but also to substantially extend their shelf-life and bolster safety standards. HPP is the most used among non-thermal food processing technologies. While its direct application to milk for consumption falls short of delivering consistent quality, it proves effective as a pretreatment step and in products using milk as a primary ingredient. In the context of meat production, HPP reduces microbial loads and extends shelf-life, yet concerns persist regarding its impact on product quality. The absence of in-depth studies regarding the attributes of carrots that support pathogen regeneration emphasizes the need for comprehensive research in this area, which could have far-reaching implications for similar fruit and vegetable products. This review underscores the need for a balanced assessment of HPP's effects on food safety and quality, offering insights that can guide the food industry in adopting this technology while ensuring consumer satisfaction and safety.

Effect of PEF Treatment on Chosen Properties of Raw and Hot Air- and Freeze-Dried Poultry Meat

The properties of fresh meat, such as high water activity, a slightly acidic reaction, and the availability of carbohydrates and proteins, make it a microbiologically unstable and easily perishable raw material. One of the oldest food preservation techniques is drying. Furthermore, non-thermal food processing techniques such as pulse electric field (PEF) treatment can be used to support the drying process and change the properties of the obtained product. Thus, this study aimed to analyze the impact of pulsed electric field treatment on the hot air-drying and freeze-drying of poultry meat as well as on the quality of the dried meat. The PEF pretreatment and drying methods significantly altered the physical characteristics of the poultry meat. The PEF treatment enhanced the efficiency of freeze-drying by electroporation, reducing drying time and shrinkage. However, in the hot air-drying, the PEF-treated samples prolonged drying, potentially due to muscle structure damage and increased shrinkage. The pretreatment techniques affected the structure of the meat and positively influenced the higher porosity and lower shrinkage. Also, drying decreased the water activity and increased the dry matter content, which ensured the safety of the final product. The freeze-dried material exhibited a higher rehydration rate, improved hygroscopic properties, and better meat color compared to the hot air-dried material. Nevertheless, the selection of the process parameters, for both the pretreatment and drying process, is crucial to ensure a high quality of the dried meat product and should be selected carefully in order to guarantee that the highest quality of the dried product is obtained.

Evaluation of multiscale mechanisms of ultrasound-assisted extraction from porous plant materials: Experiment and modeling on this intensified process

Ultrasound-assisted extraction (UAE) is an intensified mass transfer process, which can utilize natural resources effectively, but still lacks detailed mechanisms for multiscale effects. This study investigates the mass transfer mechanisms of UAE combined with material’s pore structure at multiscale. Porous material was prepared by roasting green coffee beans (GCB) at 120 °C (RCB120) and 180 °C (RCB180), and their UAE efficiency for phytochemicals (caffeine, trigonelline, chlorogenic acid, caffeic acid) were evaluated by experiment and modeling. Besides, the physicochemical properties, mass transfer kinetics, and multi-physical field simulation were studied. Results indicated that positive synergy effects on extraction existed between ultrasound and material’s pore structure. Higher mass transfer coefficients of UAE (GCB 0.16 min−1, RCB120 0.38 min−1, RCB180 0.46 min−1) was achieved with higher total porosity (4.47 %, 9.17 %, 13.52 %) and connected porosity (0 %, 3.79 %, 5.98 %). Moreover, simulation results revealed that micro acoustic streaming and pressure difference around particles were the main driving force for enhancing mass transfer, and the velocity (0.29–0.36 m/s) increased with power density (0.64–1.01 W/mL). The microscale model proved that increased yield from UAE-RCB was attributed to internal convection diffusion within particles. This study exploited a novel benefit of ultrasound on extraction and inspired its future application in non-thermal food processing.

Cold Plasma Technology Based Eco-Friendly Food Packaging Biomaterials.

Biopolymers have intrinsic drawbacks compared to traditional plastics, such as hydrophilicity, poor thermo-mechanical behaviours, and barrier characteristics. Therefore, biopolymers or their film modifications offer a chance to create packaging materials with specified properties. Cold atmospheric plasma (CAP) or Low temperature plasma (LTP) has a wide range of applications and has recently been used in the food industry as a potent tool for non-thermal food processing. Though its original purpose was to boost polymer surface energy for better adherence and printability, it has since become an effective technique for surface decontamination of food items and food packaging materials. These revolutionary innovative food processing methods enable the balance between the economic constraints and higher quality while ensuring food stability and minimal processing. For CAP to be considered as a viable alternative food processing technology, it must positively affect food quality. Food products may have their desired functional qualities by adjusting the conditions for cold plasma formation. Cold plasma is a non-thermal method that has little effects on the treated materials and is safe for the environment. In this review, we focus on recent cold plasma advances on various food matrices derived from plants and animals with the aim of highlighting potential applications, ongoing research, and market trends.

Inactivation of microorganisms by high hydrostatic pressure: A literature review

The use of high hydrostatic pressure is intended to perform non-thermal inactivation of microorganisms in food products, to ensure their freshness and to prevent foodborne infections. These infections impact the healthcare system, the food industry, and consumers directly. This study aims to analyse the literature on the effectiveness of high hydrostatic pressure against pathogenic and opportunistic microorganisms transmitted through the consumption of contaminated food. Scientific publications for 2011-2023 were selected for the review. A total of 44 scientific publications were selected, the information from which was critically analysed, systematised and presented in the form of a literature review. The mechanisms of high hydrostatic pressure’s effect on microbial cells are described. To illustrate the effectiveness of high hydrostatic pressure against microorganisms, data from selected publications regarding efficiency and treatment parameters are presented in tables. The inactivation of such clinically important microorganisms as Bacillus cereus, Campylobacter jejuni, Clostridium perfringens, Escherichia coli, Listeria monocytogenes, Salmonella spp., Staphylococcus aureus and Toxoplasma gondii in liquids and food has been demonstrated. High-pressure treatment has been shown to be a non-thermal food processing method, which distinguishes this method from traditional thermal processing methods such as boiling or pasteurization. One of the notable advantages of using high hydrostatic pressure is the non-thermal inactivation of various microorganisms, which preserves the nutritional and flavour properties of the processed product. It is also noted that food products can be processed in the final packaging, which reduces the risk of microbial contamination at the post-processing stages. The main disadvantages are the impossibility of complete inactivation of bacterial spores and the high cost of high-pressure processing equipment. Combining high-pressure treatment with other methods, such as heat treatment, can overcome the limitations of spore inactivation

Radiofrequency cold plasma – A novel tool for flavour modification in fresh and freeze-dried strawberries

Cold plasma treatment is an emerging non-thermal food processing tool. This study aimed to identify how cold plasma can improve the aroma of a model space food system (freeze-dried strawberries) by mitigating freeze-drying aroma losses. Cold plasma significantly reduced the negative impact of freeze-drying on aroma; hence, it might be useful as a secondary treatment technique for foods that require extended shelf-life with improved aroma, such as in space travel. “Zero-averaged gravity” (0.004 g), a proxy for non-terrestrial environments, reduced the abundance of two important volatile aroma compounds (methyl butanoate and methyl hexanoate) in the gas phase above strawberries; this loss was mitigated when treated by cold plasma. The impact of cold plasma on aroma was also shown to be matrix and treatment parameter-dependent, and six cold plasma treatment options were subsequently identified as enabling bespoke aroma modifications that ultimately enhanced strawberry aroma compounds.

The Impact of HPP-Assisted Biocontrol Approach on the Bacterial Communities' Dynamics and Quality Parameters of a Fermented Meat Sausage Model.

Traditional foods are increasingly valued by consumers, whose attention and purchase willingness are highly influenced by other claims such as 'natural', 'sustainable', and 'clean label'. The purpose of the present study was to evaluate the impact of a novel non-thermal food processing method (i.e., HPP-assisted biocontrol combining mild high hydrostatic pressure, listeriophage Listex, and pediocin PA-1 producing Pediococcus acidilactici) on the succession of bacterial communities and quality of a fermented sausage model. A comparative analysis of instrumental color, texture, and lipid peroxidation revealed no significant differences (p > 0.05) in these quality parameters between non- and minimally processed fermented sausages throughout 60-day refrigerated storage (4 °C). The microbiota dynamics of biotreated and untreated fermented sausages were assessed by 16S rRNA next-generation sequencing, and the alpha and beta diversity analyses revealed no dissimilarity in the structure and composition of the bacterial communities over the analyzed period. The innovative multi-hurdle technology proposed herein holds valuable potential for the manufacture of traditional fermented sausages while preserving their unique intrinsic characteristics.

Effect of pulsed light on curcumin chemical stability and antioxidant capacity.

Curcumin is the major bioactive component in turmeric with potent antioxidant activity. Little is known about how pulsed light (PL) technology (an emerging non-thermal food processing technology relying on high intensity short duration flashes of light) can affect the chemical stability and antioxidant capacity of curcumin. This study found that PL treatment of fluence levels from 0 to 12.75 J/cm2 produced a fluence-dependent reduction in curcumin content. These results paralleled the production of a tentative curcumin dimer, identified as a potential photochemical transformation product. PL-treated curcumin at relatively higher fluence levels decreased chemical-based ORAC and ABTS antioxidant capacity, relative to control (P < 0.05). This contrasted the effect observed to increase coincidently both intracellular antioxidant capacity (e.g., DCFH-DA (P < 0.05)) and GSH/GSSG ratio (P < 0.05), respectively, in cultured differentiated Caco-2 cells. In conclusion, the application of PL on curcumin results in photochemical transformation reactions, such as dimerization, which in turn, can enhance biological antioxidant capacity in differentiated Caco-2 cells.

Cold plasma as an emerging nonthermal technology for food processing: A comprehensive review

Cold plasma, a partially ionized gas maintained at low temperatures, has emerged as a promising nonthermal food processing technique with various applications, including food sterilization and improved agricultural output. By generating reactive species such as ions, radicals, and photons, cold plasma interacts with and modifies the surfaces of materials or living cells. This comprehensive review focuses on the microbial decontamination capabilities of cold plasma and its impact on a wide range of food products, including cereals, milk, fruits, vegetables, and meat. Cold plasma treatment offers distinct advantages over traditional methods such as heat treatment, chemical treatment, and irradiation. It effectively eliminates pathogenic microbes from food surfaces while preserving the quality, flavor, and nutritional content of the food. By sterilizing food surfaces and packaging materials, cold plasma significantly reduces the risk of harmful microorganism contamination. Moreover, it extends the shelf life of food products by eliminating germs, viruses, and other hazardous microbes. This review critically assesses the qualitative impact of plasma treatment, emphasizing the importance of selecting the appropriate cold plasma technology for various food products. To ensure the safety and effectiveness of cold plasma technology for commercial implementation, this review investigates the properties of cold plasma treatment for different food products. It examines the molecular connections between dietary components and cold plasma species, highlighting potential avenues for future research.

Simulation of High-voltage Pulse Generator for Environment-friendly, Non-thermal Pasteurization Applications

Nowadays, the demand for high-voltage pulse generators has begun to proliferate in many industries. Particularly in the food processing industries, the conventional method of pasteurization involves the use of heat treatment processes, which are not environment-friendly; hence, researchers are working towards environment-friendly, non-thermal food processing techniques by which the microorganisms present in the liquid food can be eliminated. High-voltage pulsed electric field technology is one of the popular non-thermal food processing techniques. Recent advancements in power electronic switching technology have facilitated the development of solid-state pulse generators for these applications. In this paper, the simulation of a high-voltage pulse generator for eco-friendly pasteurization applications has been attempted using a cascaded boost converter topology. The entire simulation is carried out using MATLAB/Simulink software. The designed two-stage cascaded boost converter is tested for varying duty cycles and loads. The results with resistive and inductive loads have been analyzed.

Non-thermal, energy efficient hydrodynamic cavitation for food processing, process intensification and extraction of natural bioactives: A review

Hydrodynamic cavitation (HC) is the process of bubbles formation, expansion, and violent collapse, which results in the generation of high pressures in the order of 100–5000 bar and temperatures in the range of 727–9727 °C for just a fraction of seconds. Increasing consumer demand for high-quality foods with higher nutritive values and fresh-like sensory attributes, food processors, scientists, and process engineers are pushed to develop innovative and effective non-thermal methods as an alternative to conventional heat treatments. Hydrodynamic cavitation can play a significant role in non-thermal food processing as it has the potential to destroy microbes and reduce enzyme activity while retaining essential nutritional and physicochemical properties. As hydrodynamic cavitation occurs in a flowing liquid, there is a decrease in local pressure followed by its recovery; hence it can be used for liquid foods. It can also be used to create stable emulsions and homogenize food constituents. Moreover, this technology can extract food constituents such as polyphenols, essential oils, pigments, etc., via biomass pretreatment, cell disruption for selective enzyme release, waste valorization, and beer brewing. Other applications related to food production include water treatment, biodiesel, and biogas production. The present review discusses the application of HC in the preservation, processing, and quality improvement of food and other related applications. The reviewed examples in this paper demonstrate the potential of hydrodynamic cavitation with further expansion toward the scaling up, which looks at commercialization as a driving force.

Effect of atmospheric cold plasma treatment on acid gelation properties of skim milk: Rheology and textural studies

Cold plasma processing is a non-thermal food processing technique that has been shown to improve the gelling properties of plant proteins by altering their structure through oxidation and crosslinking. This study aimed to investigate the effects of cold plasma treatment on the rheological properties of skim milk under different conditions, focusing on the impact of feed gas and treatment time on skim milk's sulfhydryl content, flow properties, and acid gelling behavior. Results showed that free sulfhydryl content decreased with treatment time, with a notable reduction observed after 2 min of N2-O2 plasma treatment. Skim milk treated with N2 plasma experienced a more gradual decrease in free SH content. Cold plasma increased skim milk viscosity over time. N2-O2 plasma treatment significantly affected G′40 and G′4 storage moduli, with an increase observed after 2 min of exposure but no change beyond that time. Acid gels' greenness (a* value) decreased with increasing treatment time compared to the control. Acid gel firmness of milk treated with N2-O2 plasma for 1 min significantly increased from 1.804 N to 1.912 N, and further to 2.072 N after 2 min of treatment. However, longer exposure times led to lower firmness in gels. N2 plasma treatment also significantly impacted acid gel firmness. Syneresis in acid gels decreased from 63.4 % to 57.7 % and 58.7 % after 1 and 2 min of N2-O2 plasma treatment, respectively, but increased to about 70 % after 4 min. Acid gels made from milk treated with N2 plasma experienced considerably less syneresis. The cold plasma treatment under different conditions significantly affected the properties of skim milk, with various impacts on sulfhydryl content, flow properties, and acid gelling behavior. These findings demonstrate the potential applications of cold plasma processing in the food industry to improve product properties.