Non-thermal Food Processing Technology Research Articles

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.

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.

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 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.

Ultra-high-pressure passivation of soybean agglutinin and safety evaluations.

Soybean agglutinin (SBA) is a heat-sensitive anti-nutritional factor (ANF). It affects nutrient absorption and causes organism poisoning. This study explored the SBA passivation ability and mechanism by ultra-high pressure (HHP), a non-thermal food processing technology. The results indicated that more than 500MPa HHP treatment reduced the SBA activity by destroying its secondary and tertiary structures. Also, the cell and animal experiments showed that HHP treatment reduced the cytotoxicity of SBA, improved the mice's body weight, and alleviated liver, kidney, and digestive tract damage in Vivo. These results demonstrated that HHP had a high passivation efficiency against the SBA, thereby HHP promoting the safety of soybean products. This study provided supporting evidence for ultra-high-pressure treatment applications in soybean processing.

Preservation effect of plasma-activated water (PAW) treatment on fresh walnut kernels

Fresh walnuts exhibit unique flavor and multiple biological activities, but they are highly perishable due to the lack of practical and cost-effective postharvest preservation technique. In this paper, the quality of fresh walnut kernels treated with deionized water, water containing ClO2, and plasma-activated water (PAW) for 15 min were monitored during 4 °C storage. Results showed that 100-s PAW treatment reduced the total viable count by 1.15 log CFU/g immediately after treatment. The bactericidal and bacteriostatic effects of PAW was superior to 4 mg/L ClO2. PAW-treated samples retained their flavor during 12d storage at 4 °C, while other samples generated odor at 6d. Moreover, PAW treatment could prevent nutritional loss, browning, and rancidity. The increases of peroxidase, polyphenol oxidase, and lipase activities were inhibited after PAW treatment. Hence, PAW treatment can be applied for the preservation of fresh walnut kernels due to its effect on microbial inhibition and quality maintenance. Industry relevanceNon-thermal plasma is an emerging non-thermal food processing technology due to its advantages of non-destructive, pollution-free, high efficiency and short treatment periods. In this study, plasma-activated water (PAW) was applied in the preservation of fresh walnut kernels, and inhibited flavor changes, nutritional loss, microbial growth, browning, and oxidation reaction. When approaching food preservation technologies, especially for heat-sensitive materials, PAW treatment as a novel technique appears to have far-reaching implications for increasing markets by antimicrobial properties, and avoiding the negative impacts on quality attributes.

Recent Advances in High Pressure Processing of Milk and Milk Products - A review

As the global consumers’ demand towards minimally processed freshlike foods has been continuously increasing, efforts to develop novel food processing technologies have been intensified. Among non-thermal food processing technologies, high pressure processing (HPP) seems to be more advantageous due to its environmentally friendly nature, cost efficiency, suitability for processing foods in any form and its positive impacts on foods’ shelf-life as well as providing efficient microbial safety. Microbiological inactivation efficiency of HPP has been well documented but the role of this technology in digestion efficiency of milk compounds is yet to be elucidated in detail. Also, the potential safety hazards and challenges of HPP in foods require more intense studies. This review deals with the recent developments in HPP treatment to milk and milk products.

A Pulsed Electric Field Accelerates the Mass Transfer during the Convective Drying of Carrots: Drying and Rehydration Kinetics, Texture, and Carotenoid Content.

The pulsed electric field (PEF) is a non-thermal food processing technology that induces electroporation of the cell membrane thus improving mass transfer through the cell membrane. In this study, the drying and rehydration kinetics, microstructure, and carotenoid content of carrot (Daucus carota) pretreated by PEF during convective drying at 50 °C were investigated. The PEF treatment was conducted with different field strengths (1.0-2.5 kV/cm) using a fixed pulse width of 20 µs and at a pulse frequency of 50 Hz. The PEF 2.5 kV/cm showed the shortest drying time, taking 180 min, whereas the control required 330 min for the same moisture ratio, indicating a 45% reduction in drying time. The rehydration ability also increased as the strengths of PEF increased. PEF 2.5 kV/cm resulted in 27.58% increase in moisture content compared to the control after rehydration (1 h). Three mathematical models were applied to the drying and rehydration data; the Page and Peleg models were selected as the most appropriate models to describe the drying and rehydration kinetics, respectively. The cutting force of the sample was decreased as the strength of PEF increased, and a more homogeneous cellular structure was observed in the PEF pretreatment group. The reduction in drying time by PEF was beneficial to the carotenoid content, and PEF 2.5 kV/cm showed the highest preservation content of carotenoid. Overall, these results suggested that the pretreatment of PEF and the drying and rehydration rate influence the quality of products, functional components, and cellular structure.

Dynamic alterations in protein, sensory, chemical, and oxidative properties occurring in meat during thermal and non-thermal processing techniques: A comprehensive review.

Meat processing represents an inevitable part of meat and meat products preparation for human consumption. Both thermal and non-thermal processing techniques, both commercial and domestic, are able to induce chemical and muscle's proteins modification which can have implication on oxidative and sensory meat characteristics. Consumers' necessity for minimally processed foods has paved a successful way to unprecedented exploration into various novel non-thermal food processing techniques. Processing of meat can have serious implications on its nutritional profile and digestibility of meat proteins in the digestive system. A plethora of food processing techniques can potentially induce alterations in the protein structure, palatability, bioavailability and digestibility via various phenomena predominantly denaturation and Maillard reaction. Apart from these, sensory attributes such as color, crispness, hardness, and total acceptance get adversely affected during various thermal treatments in meat. A major incentive in the adoption of non-thermal food processing is its energy efficiency. Considering this, several non-thermal processing techniques have been developed for evading the effects of conventional thermal treatments on food materials with respect to Maillard reactions, color changes, and off-flavor development. Few significant non-thermal processing techniques, such as microwave heating, comminution, and enzyme addition can positively affect protein digestibility as well as enhance the value of the final product. Furthermore, ultrasound, irradiation, high-pressure processing, and pulsed electric fields are other pivotal non-thermal food processing technologies in meat and meat-related products. The present review examines how different thermal and non-thermal processing techniques, such as sous-vide, microwave, stewing, roasting, boiling, frying, grilling, and steam cooking, affect meat proteins, chemical composition, oxidation, and sensory profile.

Effect of E-beam irradiation on the qualitative attributes of shrimp (Penaeus vannamei)

As a non-thermal food processing technology, Electron beam (E-beam) irradiation has been used to enhance microbial safety by deactivating unwanted spoilage and pathogenic microorganisms in food industry. This study evaluated the effects of E-beam irradiation at doses killing SARS-COV-2 on qualities and sensory attributes. The results showed that irradiation caused little effect on the proximate composition, amino acid content, texture, and sensory attributes (P > 0.05). However, E-beam increased TBARS (Thiobarbituric acid reactive substances) and lowered vitamin E content in dose-dependently. Irradiation up to 10 kGy significantly decreased unsaturated fatty acid (UFA) content and inhibited the increase in TVB-N (The total volatile basic nitrogen) while reducing cohesiveness and chewiness (P < 0.05). E-beam irradiation with 7–10 kGy caused greater ΔE values (ΔE > 5) via the significant increase of b*, accompanied by big visual difference in shrimp (P < 0.05). A dose of 4 kGy E-beam irradiation was recommended without altering its physicochemical properties and sensory attributes.

DEVELOPMENT OF A NEW DEVICE FOR APPLYING ATMOSPHERIC PRESSURE COLD PLASMA ON FOODS

The studies on cold plasma, a non-thermal food processing technology, have been recently focused on extending the shelf life of foods and controlling pathogenic microorganisms since its antimicrobial activities were recognized. Atmospheric pressure cold plasma is a cost-effective and user-friendly technique since it does not require a vacuum environment and apparatus. In this study, a new device that produces atmospheric pressure cold plasma in large volumes has been designed and produced to treat various types and properties of food. The system can operate at three different modes, producing direct (Device mode-I) and indirect (Device mode-II) Volume Dielectric Barrier Discharge (VDBD) and Surface Dielectric Barrier Discharge (SDBD) plasma (Device mode-III). The system can be operated consecutively without any problems. The cold plasmas produced in three different modes were applied to different food types, and the foods were examined whether cold plasmas caused a noticeable change in sensory properties. The reactions caused by the system under different operating conditions were measured by optical emission spectroscopy, and the chemical interactions that the foods might be exposed to during plasma treatment were determined. The types of plasma particles that can be effective in food-plasma applications were discussed. The sensory analysis results showed that various foods such as chicken, fish, apple, and milk could be treated with atmospheric pressure cold plasma without causing significant changes in their sensory properties.

Potential applications of pulsed electric field in the fermented wine industry.

Fermented wine refers to alcoholic beverages with complex flavor substances directly produced by raw materials (fruit or rice) through microbial fermentation (yeast and bacteria). Its production steps usually include saccharification, fermentation, filtration, sterilization, aging, etc., which is a complicated and time-consuming process. Pulsed electric field (PEF) is a promising non-thermal food processing technology. Researchers have made tremendous progress in the potential application of PEF in the fermented wine industry over the past few years. The objective of this paper is to systematically review the achievements of PEF technology applied to the winemaking and aging process of fermented wine. Research on the application of PEF in fermented wine suggests that PEF treatment has the following advantages: (1) shortening the maceration time of brewing materials; (2) promoting the extraction of main functional components; (3) enhancing the color of fermented wine; (4) inactivating spoilage microorganisms; and (5) accelerating the formation of aroma substances. These are mainly related to PEF-induced electroporation of biomembranes, changes in molecular structure and the occurrence of chemical reactions. In addition, the key points of PEF treatments for fermented wine are discussed and some negative impacts and research directions are proposed.

Employment of cold atmospheric plasma in chilled chicken breasts and the analysis of microbial diversity after the shelf-life storage

Cold atmospheric plasma, featured as a non-thermal food processing technology has gained prominent attention for its practical application. The demand for chilled chicken has increased rapidly due to its nutritious value. However, chilled chicken often suffers from a short shelf life due to its susceptibility to spoilage. In this study, air- and nitrogen plasma were applied to investigate microbial inactivation effects and shelf-life extension of chilled chicken. Meanwhile, the microbial diversity of chicken breasts after air and nitrogen-CAP treatment and at the end of shelf-life was analyzed. Results illustrated that the inactivation effects of air plasma were more potent than that of nitrogen plasma, while nitrogen plasma could better maintain the sensory properties. Also, further investigation illustrated that air- and nitrogen-CAP could change the microbial community significantly. Both treatment time and working gases were essential experimental parameters that affected the microbial community composition.

Impacts of Cold Plasma Technology on Sensory, Nutritional and Safety Quality of Food: A Review.

As an emerging non-thermal food processing technology, cold plasma (CP) technology has been widely applied in food preservation due to its high efficiency, greenness and lack of chemical residues. Recent studies have indicated that CP technology also has an impressing effect on improving food quality. This review summarized the impact of CP on the functional composition and quality characteristics of various food products. CP technology can prevent the growth of spoilage microorganisms while maintaining the physical and chemical properties of the food. It can maintain the color, flavor and texture of food. CP can cause changes in protein structure and function, lipid oxidation, vitamin and monosaccharide degradation, starch modification and the retention of phenolic substances. Additionally, it also degrades allergens and toxins in food. In this review, the effects of CP on organoleptic properties, nutrient content, safety performance for food and the factors that cause these changes were concluded. This review also highlights the current application limitations and future development directions of CP technology in the food industry. This review enables us to more comprehensively understand the impacts of CP technology on food quality and promotes the healthy application of CP technology in the food industry.

Investigation on the Effects of a Pulsed Electric Field (PEF) Continuous System Implemented in an Industrial Olive Oil Plant.

The aim of this study was to investigate how the treatment of olive paste of the Picholine variety with pulsed electric fields (PEF) under real operating conditions in a large-scale olive oil extraction plant affects the extractability, chemical composition and sensory profile of the oils. The application of pulsed electric fields (PEF) as a non-thermal food processing technology is interesting for many food extraction processes. The results of this study show that pulsed electric fields can be used as a pretreatment before oil separation to increase the extractability of the process and improve the content of functional components. The application of pulsed electric field (PEF) treatment (2.4 kV/cm, 4 kJ/kg, 6 µs pulse width) to olive paste through a continuous system significantly increased the extractability and total concentration of phenols (especially oleuropein derivatives) compared to the control. In addition, the volatile compounds, α-tocopherol, the fatty acid profile and the main legal quality parameters of extra virgin olive oil (EVOO), including free acidity, peroxide values, extinction indices and sensory analysis, were evaluated. The pulsed electric fields (PEF) treatment did not modify these EVOO quality parameters, neither the α-tocopherol content nor the volatile profile. The sensory properties of EVOO were not affected as well as the PEF treatment showed a similar intensity of fruity and pungent attributes without any off-flavor according to the European Union legal standards. An increase in the bitter taste attribute was observed in the PEF oils. Consequently, this study demonstrates that pulsed electric fields (PEF) processing could be implemented in olive oil processing as pretreatment for improving the efficiency of the process.

Enhancing the Biological Activities of Food Protein-Derived Peptides Using Non-Thermal Technologies: A Review.

Bioactive peptides (BPs) derived from animal and plant proteins are important food functional ingredients with many promising health-promoting properties. In the food industry, enzymatic hydrolysis is the most common technique employed for the liberation of BPs from proteins in which conventional heat treatment is used as pre-treatment to enhance hydrolytic action. In recent years, application of non-thermal food processing technologies such as ultrasound (US), high-pressure processing (HPP), and pulsed electric field (PEF) as pre-treatment methods has gained considerable research attention owing to the enhancement in yield and bioactivity of resulting peptides. This review provides an overview of bioactivities of peptides obtained from animal and plant proteins and an insight into the impact of US, HPP, and PEF as non-thermal treatment prior to enzymolysis on the generation of food-derived BPs and resulting bioactivities. US, HPP, and PEF were reported to improve antioxidant, angiotensin-converting enzyme (ACE)-inhibitory, antimicrobial, and antidiabetic properties of the food-derived BPs. The primary modes of action are due to conformational changes of food proteins caused by US, HPP, and PEF, improving the susceptibility of proteins to protease cleavage and subsequent proteolysis. However, the use of other non-thermal techniques such as cold plasma, radiofrequency electric field, dense phase carbon dioxide, and oscillating magnetic fields has not been examined in the generation of BPs from food proteins.

Inactivation of viruses related to foodborne infections using cold plasma technology

AbstractGlobally, there is a rise in day‐to‐day demand for minimally processed foods to supply nutritious, wholesomeness and safe foods to the consumers. Contamination of food by pathogens is a serious problem resulting in several outbreaks. Food pathogens like molds, bacteria were detectable and can be inactivated. The virus detection in foods is always a difficult task as their presence could not alter any noticeable change in the quality. Norovirus, Hepatitis A viruses are well‐known for their foodborne outbreaks and illnesses. Enveloped viruses are resistant and have the stability to the current traditional preservation methods due to the presence of a protective capsid layer and an envelope. The current thermal processing has shown significant effect on the product quality. The use of chemical disinfestation compounds is not suitable for food commodities. There is a need for alternative nonthermal food processing technologies for decontamination of food and food packages and preserving the food quality as well. Cold plasma is one of the emerging nonthermal, chemical‐free residues, and eco‐friendly technology widely being applied to the different food sectors. The main antiviral mechanism is the disruption of the capsid protein layer, the oxidation and denaturation of viral proteins. The method has also caused damage to the envelope layer and genetic material. This review focuses on cold plasma inactivation efficiency on different viruses.

Inactivation of foodborne viruses by the cold plasma technology

Cold plasma (CP) is an innovative non-thermal food processing method. CP refers to a partially or completely ionized gas containing reactive chemical species, which are active against microorganisms, including viruses or enzymes of foods. CP has a minimal effect on the quality attributes of foods and can also elongate the shelf life of foods. Foodborne outbreaks caused by viruses have been increased in various countries in recent years. The research works on the inactivation effect of CP against viruses including foodborne viruses have been also increased in recent years. The most important foodborne viruses are human norovirus (HuNoV) and hepatitis A virus (HAV), involved in several outbreaks worldwide. Human astrovirus (HAstV), human adenovirus (HuAdV), Aichi virus (AiV), sapovirus (SaV) and enterovirus (EV) are also notable foodborne viruses and were associated in sporadic cases. The CP treatment proved efficient for the inactivation of foodborne viruses such as HuNoV and HAV. The present work reviews the CP as a non-thermal food processing technology and present the published data on the effect of CP process on foodborne viruses in foods.

Hydrodynamic Cavitation: A Novel Non-Thermal Liquid Food Processing Technology.

Hydrodynamic cavitation (HC), as a novel non-thermal processing technology, has recently shown unique effects on the properties of various liquid foods. The extreme conditions of pressure at ~500 bar, local hotspots with ~5,000 K, and oxidation created by HC can help obtain characteristic products with high quality and special taste. Moreover, compared with other emerging non-thermal approaches, the feature of the HC phenomenon and its generation mechanism helps determine that HC is more suitable for industrial-scale processing. This mini-review summarizes the current knowledge of the recent advances in HC-based liquid food processing. The principle of HC is briefly introduced. The effectiveness of HC on the various physical (e.g., particle size, viscosity, temperature, and stability), chemical (nutrition loss), and biological characteristics (microorganism inactivation) of various liquid foods are evaluated. Finally, several recommendations for future research on the HC technique are provided.

Dairy foods and novel thermal and non-thermal processing: A bibliometric analysis

Processing dairy products by conventional methods, such as pasteurization, can induce chemical reactions and physicochemical alterations, compromising nutritional and sensory quality. Thus, there is a growing worldwide demand for studies related to emerging processing technologies. This study aims to describe trends related to dairy processing through the application of emerging technologies. In this sense, articles published in this area of research in the last decade were retrieved from scientific databases, and their findings were analyzed through a bibliometric study. Reviews and original articles expressed 40 and 60% of publications, respectively, and novel thermal and non-thermal processing studies showed multidisciplinary approaches. Ohmic heating and microwave heating were the most discussed novel thermal technologies in the processing of dairy products. Among non-thermal technologies, there was a more significant trend in studies on ultrasound, high hydrostatic pressure, and pulsed electric fields. The impact of the application of novel food technologies concerning quality, safety, and energy efficiency compared to traditional methods and the influence of critical operating conditions for process control were the most studied areas. Furthermore, the impact of novel non-thermal food processing technologies from the consumer's point of view is emerging. These results can be used for future innovations by the dairy industry. Industrial relevanceDairy foods are important food matrices considering a nutritional and functional point of view and recommended in a regular diet for consumers of all ages. Therefore, a bibliometric analysis was performed considering dairy foods and novel thermal and non-thermal processing. A higher number of publications considering non-thermal technologies was reported, highlighting the need for food processing without applying high temperatures. High hydrostatic pressure, ultrasonication, and pulsed electric fields were the most discussed non-thermal technologies. At the same time, ohmic heating and microwave heating were the most reported thermal technologies. Furthermore, the most used applications, critical process parameters, and food properties to be evaluated are highlighted and discussed. The results could be used as a basis for the dairy processors to implement non-conventional technologies as an option at their production lines, as they demonstrate the most relevant process parameters and food characteristics to be evaluated, helping them to choose the parameters with higher impact and firstly consider them. Furthermore, consumers studies are important and should evaluate consumer perception about the products and the perceived benefits and risks of the novel technologies.