The Effect of Pulsed Electric Fields (PEF) Combined with Temperature and Natural Preservatives on the Quality and Microbiological Shelf-Life of Cantaloupe Juice

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.

Pulsed Electric Field Treatment Modulates Gene Expression and Stress Responses in Fusarium-Infected Malting Barley

Malting is a critical step in barley (Hordeum vulgare) processing, transforming grain into a key raw material for brewing and food production. However, the process is often compromised by Fusarium spp., pathogens responsible for Fusarium Head Blight, which reduces grain quality and safety. Pulsed electric field (PEF) treatment, a promising non-thermal technology, has been studied for its potential to inactivate microbial pathogens and mitigate infection-related stress. In this study, we investigated transcriptional responses in barley infected with Fusarium spp. during malting, both with and without PEF treatment. RNA sequencing identified over 12,000 differentially expressed genes (DEGs) across four malting stages, with the third stage (24 h of germination) showing the highest transcriptional activity. DEGs were significantly enriched in pathways related to oxidative stress management and abscisic acid signaling, underscoring their importance in stress adaptation. Barley treated with PEF exhibited fewer DEGs in later malting stages compared to untreated samples, suggesting that PEF alleviates stress induced by both Fusarium infection and the malting process. Enrichment analysis further revealed that PEF treatment up-regulated stress-related pathways while down-regulating genes associated with photosynthesis and cell wall biogenesis. These findings provide novel insights into barley stress responses during malting and highlight the potential of PEF as a tool for enhancing malt quality under stress conditions.

Induced electric field as alternative pasteurization to improve microbiological safety and quality of bayberry juice

Recently, unconventional techniques like induced electric field (IEF) for continuous pasteurization of liquid food have received great attention. In this study, the effect of IEF on temperature rise, microbiological and quality characteristics of bayberry juice was investigated. Voltage, current, and flow rate affected the terminal temperature. Both IEF (600 V, 4 L/h; 700 V, 6 L/h) and thermal pasteurization (95 °C, 2 min) completely inactivated total plate count, coliforms, yeast and mold in bayberry juice. The pH, total soluble solid and titratable acidity did not vary significantly post-IEF, but conductivity changed slightly. IEF-treated samples exhibited the lowest ΔE values without exceeding 3. Thermal pasteurization (95 °C, 2 min) scored the lowest in color, flavor, odor, and acceptance. GC-MS results demonstrated a significant increase in the content of total volatile compounds following IEF treatments, with the maximum increment reaching 10.65 %. Generally, IEF is a potential technology for processing liquid beverages.

Influence of induced electric field on cold brew coffee: Temperature rise, physicochemical properties, and shelf life

Cold brew coffee has gained significant popularity in the global market. This study examined the differences in chemical properties and flavor of cold brew coffee during storage, which was subjected to low-temperature pasteurization using induced electric field (IEF) at temperatures of 52 °C and 58 °C for 92 s, corresponding to 18.52 V/cm and 25.92 V/cm. Then, a high-temperature short-time (HTST) pasteurization was performed at 93 °C for 2 min as the control. Microbial analysis demonstrated that IEF treatment at 58 °C achieved a bactericidal effect. Both the IEF and HTST groups exhibited consistent trends in total sugar and total phenol content, showing approximately 28 μg GAE/mL after 28 days for IEF-2 group, compared to 25 μg/mL for HTST. Flavor analysis indicated that IEF group preserved the aroma characteristics during storage period. Further, IEF treatment effectively retained the key aroma compounds in cold brew coffee through GC-MS analysis, particularly pyrazine compounds with a relative content increased by 0.96 % in IEF-2 group after 28 days. Moreover, the bioactive compounds initially increased and subsequently decreased over the storage.

Effects of Pulsed Electric Field and High-Pressure Processing Treatments on the Juice Yield and Quality of Sea Buckthorn

Sea buckthorn juice has high nutritional value and a rich flavor that consumers enjoy. Traditional sea buckthorn thermal processing (TP) technology has problems such as low juice yield, poor quality, and poor flavor. Sea buckthorn berries are processed using a technique combining pulsed electric field (PEF) and high-pressure processing (HPP) to increase juice yield and study its impact on the quality and volatile aroma of sea buckthorn juice. Results have show that, compared with TP, under the condition of PEF-HPP, the juice yield of sea buckthorn significantly increased by 11.37% (p > 0.05); TP and PEF-HPP treatments could effectively kill microorganisms in sea buckthorn juice, but the quality of sea buckthorn juice decreased significantly after TP treatment (p > 0.05), whereas PEF-HPP coupling technology could maximally retain the nutrients of sea buckthorn juice while inhibiting enzymatic browning to improve color, viscosity, and particle size. The flavor of sea buckthorn juice is analyzed using electronic nose (E-nose) and gas chromatography-ion mobility spectrometer (GC-IMS) techniques, and it has been shown that PEF-HPP retains more characteristic volatile organic compounds (VOCs) of sea buckthorn while avoiding the acrid and pungent flavors produced by TP, such as benzaldehyde, (E)-2-heptenal, and pentanoic acid, among others, which improves the sensory quality of sea buckthorn juice. PEF-HPP technology is environmentally friendly and efficient, with significant economic benefits. Research data provide information and a theoretical basis for the sea buckthorn juice processing industry.

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.

Advances in pulsed electric stimuli as a physical method for treating liquid foods

There is a need for alternative technologies that can deliver safe and nutritious foods at lower costs as compared to conventional processes. Pulsed electric field (PEF) technology has been utilised for a plethora of different applications in the life and physical sciences, such as gene/drug delivery in medicine and extraction of bioactive compounds in food science and technology. PEF technology for treating liquid foods involves engineering principles to develop the equipment, and quantitative biochemistry and microbiology techniques to validate the process. There are numerous challenges to address for its application in liquid foods such as the 5-log pathogen reduction target in food safety, maintaining the food quality, and scale up of this physical approach for industrial integration. Here, we present the engineering principles associated with pulsed electric fields, related inactivation models of microorganisms, electroporation and electropermeabilization theory, to increase the quality and safety of liquid foods; including water, milk, beer, wine, fruit juices, cider, and liquid eggs. Ultimately, we discuss the outlook of the field and emphasise research gaps.

Effect of High Hydrostatic Pressure and Pulsed Electric Fields Processes on Microbial Safety and Quality of Black/Red Raspberry Juice

Black and red raspberries are fruits with a high phenolic and vitamin C content but are highly susceptible to deterioration. The effect of high hydrostatic pressure (HHP 400−600 MPa/CUT-10 min) and pulsed electric fields (PEF, frequency 100−500 Hz, pulse number 100, electric field strength from 11.3 to 23.3 kV/cm, and specific energy from 19.7 to 168.4 kJ/L) processes on black/red raspberry juice was studied. The effect on the inactivation of microorganisms and pectin methylesterase (PME) activity, physicochemical parameters (pH, acidity, total soluble solids (°Brix), and water activity (aw)), vitamin C and phenolic compounds content were also determined. Results reveal that all HHP-treatments produced the highest (p < 0.05) log-reduction of molds (log 1.85 to 3.72), and yeast (log 3.19), in comparison with PEF-treatments. Increments in pH, acidity, and TSS values attributed to compounds’ decompartmentalization were found. PME activity was partially inactivated by HHP-treatment at 600 MPa/10 min (22% of inactivation) and PEF-treatment at 200 Hz/168.4 kJ/L (19% of inactivation). Increment in vitamin C and TPC was also observed. The highest increment in TPC (79% of increment) and vitamin C (77% of increment) was observed with PEF at 200 Hz/168.4 kJ/L. The putative effect of HHP and PEF on microbial safety, enzyme inactivation, and phytochemical retention is also discussed in detail. In conclusion, HHP and PEF improve phytochemical compounds’ content, microbial safety, and quality of black/red raspberry juice.

Applications of Innovative Non-Thermal Pulsed Electric Field Technology in Developing Safer and Healthier Fruit Juices

The deactivation of degrading and pectinolytic enzymes is crucial in the fruit juice industry. In commercial fruit juice production, a variety of approaches are applied to inactivate degradative enzymes. One of the most extensively utilized traditional procedures for improving the general acceptability of juice is thermal heat treatment. The utilization of a non-thermal pulsed electric field (PEF) as a promising technology for retaining the fresh-like qualities of juice by efficiently inactivating enzymes and bacteria will be discussed in this review. Induced structural alteration provides for energy savings, reduced raw material waste, and the development of new products. PEF alters the α-helix conformation and changes the active site of enzymes. Furthermore, PEF-treated juices restore enzymatic activity during storage due to either partial enzyme inactivation or the presence of PEF-resistant isozymes. The increase in activity sites caused by structural changes causes the enzymes to be hyperactivated. PEF pretreatments or their combination with other nonthermal techniques improve enzyme activation. For endogenous enzyme inactivation, a clean-label hurdle technology based on PEF and mild temperature could be utilized instead of harsh heat treatments. Furthermore, by substituting or combining conventional pasteurization with PEF technology for improved preservation of both fruit and vegetable juices, PEF technology has enormous economic potential. PEF treatment has advantages not only in terms of product quality but also in terms of manufacturing. Extending the shelf life simplifies production planning and broadens the product range significantly. Supermarkets can be served from the warehouse by increasing storage stability. As storage stability improves, set-up and cleaning durations decrease, and flexibility increases, with only minor product adjustments required throughout the manufacturing process.