Dielectric barrier discharge cold atmospheric plasma: Influence of processing parameters on microbial inactivation in meat and meat products

Cold plasma: A nonthermal pretreatment, extraction, and solvent activation technique for obtaining bioactive compounds from agro-food industrial biomass

The present review provides a comprehensive overview of cold plasma treatment and its applications in solvent activation and bioactive component extraction. The study has summarized the principles, types, uses, and mechanisms of cold plasma treatment in activating various solvents, extracting biomolecules, and affecting the characteristics of the extracted compound. This review also explores the environmental benefits of implementing this sustainable technology, highlighting the influence of key parameters such as gas type, treatment time, voltage, and plasma flow rate on the extraction process, providing insights into optimizing these conditions for maximum efficiency. In addition, future trends and research needs for advancing cold plasma-assisted extraction have also been proposed. All biomolecules exhibit specific characteristics; still, the influence of cold plasma treatment varies depending on treatment parameters and product properties, including the source material utilized in the extraction process. Most research has shown that cold plasma treatment can cause cell disruption due to reactive species generation and enhances solvent penetration; thereby, it helps in improving extraction yield with negligible effects on characteristics. With the growing demand for natural bioactive compounds in the nutraceutical, pharmaceutical, and food sectors, cold plasma offers a promising alternative to conventional thermal and chemical extraction techniques. This review concisely discusses the benefits and challenges of cold plasma treatment and the need for additional research.

Plasma-Activated Water (PAW) Decontamination of Foodborne Bacteria in Shucked Oyster Meats Using a Compact Flow-Through Generator

This study explored the effectiveness of plasma-activated water (PAW), generated by a newly developed compact generator, for decontaminating foodborne bacteria in oyster meats. The generator effectively produced PAW with antibacterial activity when the water passed through the plasma reactor in a single cycle. The temperature of the PAW produced by the developed device did not exceed 40 °C, enabling its direct application to biological tissues immediately after production and discharge from the plasma reactor. The effects of flow rates and post-discharge times on key reactive species-including hydrogen peroxide, nitrite, and nitrate-were analyzed, along with pH and temperature. Freshly produced PAW can completely inhibit both E. coli and S. aureus in vitro, with a 5-log reduction within 5 min of treatment. Application to oyster meats led to an 86.6% and 87.9% inactivation of V. cholerae and V. parahaemolyticus, respectively. These research findings indicate that PAW generated using the developed compact flow-through generator holds promise as a food safety solution for households. The fact that complete foodborne pathogen elimination was not achieved emphasizes the need for further optimization.

Cold plasma as an emerging catalytic route for oil modification

The effect of cold plasma on the oxidation, hydrogenation, transesterification, and pyrolysis reactions is investigated. Also, the effect of cold plasma parameters on these reactions and the advantages and challenges of cold plasma are investigated. Cold plasma can produce low-trans partial hydrogenated oil at low temperature without catalyst. Besides, oil modified through transesterification and pyrolysis processes using cold plasma technique can be used for biofuel production. Oxidation during cold plasma treatment can be inhibited by omitting the oxygen from carrier gas and applying the lowest possible input power and treatment time. One of the main challenges of using dielectric barrier discharge device at large scale is providing high plasma intensity for large amounts of raw materials. In microwave discharge plasma device, high capital investment is the main challenge for scaling up. In conclusion, cold plasma technique can hydrogenate and transesterify oils at low temperature.

Effects of Different Preservation Techniques on Microbial and Physicochemical Quality Characteristics of Sauced Beef Under Chilled Storage

This study investigates the effects of different preservation methods-tray packing (control), vacuum packing (T1), and tray packing with 2 mg/mL pepper essential oil (T2)-on the quality of sauced beef during 4 °C storage for 1, 5, 9, and 13 days. The results revealed that T2 significantly inhibited microbial growth, as reflected by reduced total aerobic counts (TACs), minimized lipid oxidation (indicated by lower thiobarbituric acid reactive substances (TBARSs)), and reduced protein degradation (evidenced by decreased total volatile basic nitrogen (TVB-N)). Additionally, T2 delayed the reduction in inosine-5'-monophosphate (IMP) and accumulation of hypoxanthine (Hx), effectively extending shelf life and preserving sensory quality. T1 also showed beneficial effects in limiting oxygen-related spoilage, as demonstrated by lower TAC and TBARS levels. In contrast, the control group showed limited effectiveness in preserving the quality of sauced beef, as indicated by higher microbial counts and more pronounced lipid and protein degradation. These findings provide a theoretical basis for improving sauced beef preservation by highlighting the effectiveness of different packaging methods and the potential of pepper essential oil as a natural preservative.

Recent Advances in Food Safety: Nanostructure-Sensitized Surface-Enhanced Raman Sensing

Food safety is directly related to human health and has attracted intense attention all over the world. Surface-enhanced Raman scattering (SERS), as a rapid and selective technique, has been widely applied in monitoring food safety. SERS substrates, as an essential factor for sensing design, greatly influence the analytical performance. Currently, nanostructure-based SERS substrates have garnered significant interest due to their excellent merits in improving the sensitivity, specificity, and stability, holding great potential for the rapid and accurate sensing of food contaminants in complex matrices. This review summarizes the fundamentals of Raman spectroscopy and the used nanostructures for designing the SERS platform, including precious metal nanoparticles, metal-organic frameworks, polymers, and semiconductors. Moreover, it introduces the mechanisms and applications of nanostructures for enhancing SERS signals for monitoring hazardous substances, such as foodborne bacteria, pesticide and veterinary drug residues, food additives, illegal adulterants, and packaging material contamination. Finally, with the continuous progress of nanostructure technology and the continuous improvement of SERS technology, its application prospect in food safety testing will be broader.

Effect of Low-Temperature Plasma Sterilization on the Quality of Pre-Prepared Tomato-Stewed Beef Brisket During Storage: Microorganism, Freshness, Protein Oxidation and Flavor Characteristics

Traditional tomato-braised beef brisket with potatoes is celebrated for its rich, complex flavors and culinary appeal but requires lengthy preparation. Pre-packaged versions of the dish rely on thermal sterilization for safety; however, high-temperature processing accelerates protein and lipid oxidation, thereby compromising its sensory quality. As the demand for ready-to-eat meals grows, the food industry faces the challenge of ensuring microbial safety while preserving flavor integrity. In this study, low-temperature plasma sterilization (LTPS) (160 KV, 450 s) was evaluated as a non-thermal alternative to conventional high-temperature short-time (HSS) sterilization. Furthermore, a comprehensive analysis was conducted over a 10-day storage period, assessing microbial viability, physicochemical properties (pH, shear force, and water-holding capacity), oxidative markers (TBARS, TVB-N, and protein carbonyls), volatile compounds (GC-MS), and electronic nose (e-nose) responses. The results revealed that LTPS (160 kV, 450 s) successfully maintained bacterial counts below regulatory limits (5 lg CFU/g) for 72 h, ensuring that the microbial indicators of short-term processed products sold to supermarkets through cold chain logistics were in the safety range. Additionally, LTPS-treated samples showed a 4.2% higher water-holding capacity (p < 0.05) during storage, indicating improved preservation of texture. Furthermore, LTPS-treated samples exhibited 32% lower lipid oxidation (p < 0.05) and retained 18% higher sulfhydryl content (p < 0.05) compared to HSS, indicating reduced protein oxidation. GC-MS and e-nose analyses showed that LTPS preserved aldehydes and ketones associated with meaty aromas, while HSS contributed to sulfur-like off-flavors. Principal component analysis showed that the LTPS samples had shorter distances across various storage periods compared to HSS, indicating reduced differences in aroma difference. The findings of this study demonstrate LTPS's dual efficacy in microbial control and aroma preservation. The technology presents a viable strategy for extending the shelf life of pre-prepared meat dishes while reducing oxidative and flavor deterioration, thereby establishing a solid foundation for LTPS application in the pre-prepared food sector.

The molecular reactive pathway between lipoxygenase and lipase and reactive species generated in dielectric barrier discharge atmospheric cold plasma: An investigation using molecular docking

The molecular docking was explored to study the interactions between reactive species generated by cold plasma and the enzymes lipoxygenase (LOX) and lipase (LPS), with the aim of elucidating the molecular mechanisms governing these interactions. Molecular docking results suggest that both LOX and LPS are primarily involved in hydrogen bonding interactions with the seven reactive species. The key binding sites for LOX and LPS were identified as Ile 663 and Glu 188, respectively. Notably, the lowest docking energy was observed between LOX and NO (-13.75 kcal/mol), whereas for LPS, it is between LPS and NO3 (-12.08 kcal/mol). Increased treatment voltage and time resulted in higher inactivation levels, with LPS exhibiting higher residual activity compared to LOX. When the voltage was 75 kV and the time was 120 s, the residual activities of LOX and LPS were 42.88% and 56.77%, respectively. Consequently, the results enhance our understanding of the mechanisms underlying the inhibition of enzyme activity by reactive species generated by cold plasma. Moreover, cold plasma may serve as a novel preservation technology for inhibiting lipid oxidation of food by controlling enzyme activity.

Combined high voltage atmospheric cold plasma and ultraviolet-cold plasma inhibited Aspergillus flavus growth and improved physicochemical properties of protein in peanuts

To improve the application value of peanuts, the fungicidal effect and physicochemical properties of the protein in peanuts were investigated by combining high voltage atmospheric cold plasma (HVCP) and ultraviolet-cold plasma (UVCP) in this study. Compared to the single HVCP or UVCP treatment, the combined treatments exhibited a higher fungicidal efficiency of A. flavus spores in peanuts, decreasing by 0.79-2.97 log10 cfu/g after 8-min treatment. The A. flavus growth and aflatoxin production in peanuts during storage were also lower than the single plasma groups. Moreover, cold plasma treatments could modify the molecular structures of protein in peanuts by changing secondary and tertiary structures, decreasing particle size and increasing zeta potential, which contributed to improve the solubility and emulsification of protein. Overall, this research provides a unique strategy for the combined application of cold plasma in grain decontamination and protein modification.

Cold plasma reengineers peanut protein isolate: Unveiling changes in functionality, rheology, and structure

This study investigates the effects of cold plasma (CP) treatment on peanut protein isolate (PPI), focusing on functionality, rheology, and structural modifications across various treatment times (0, 90, 180, 270, 360, and 450 s) and voltages (120, 140, and 160 kV). Key findings include a significant increase in solubility from 9.99 mg/mL to 15.98 mg/mL, as well as 161.07 % enhanced water-holding capacity (WHC) and 448.45 % oil-holding capacity (OHC). CP treatment also improved foaming capacity (FC) to 186.46 % and increased emulsion capacity (EC) and emulsion stability (ES) by 185.90 % at 160 kV. Rheological analysis showed shear-thinning behaviour, with viscosity decreasing as the shear rate increased-higher voltages (140 kV and 160 kV) further reduced viscosity, indicating lower resistance to flow. Additionally, CP-treated PPI exhibited viscoelasticity, with increased storage and loss moduli at higher frequencies, indicating greater stiffness. Spectroscopic studies demonstrated shifts in the protein's secondary structure, altering the balance among alpha-helix, beta-sheet, and random coil components, which highlights CP's role in reengineering PPI. FTIR-ATR spectra revealed reductions in the 3200-3400 cm-1 range, suggesting changes in protein backbone vibrations and hydrogen bonding. Particle size analysis showed significant increases, especially at higher voltages and longer treatment times, stabilizing after 270 s. Zeta potential assays indicated a gradual decrease in negative surface charge, suggesting enhanced protein aggregation. Overall, CP treatment significantly improves the functional and rheological properties of PPI while inducing structural changes, making it more suitable for applications in the food and pharmaceutical industries.

Cold Plasma Treatment of Quinoa Grains: Changes in Phytic Acid, Saponin, Content, and Antioxidant Capacity

The impact of atmospheric cold plasma (ACP) treatment (at 50 and 60 kV for 5 and 10 min) on nutritional (total phenolic and flavonoids contents, antioxidant capacity, and TBARs) and antinutritional (saponin and phytic acid) characteristics of quinoa grains has been investigated at this study. Results indicated that ACP treatment is significantly effective to reduce the antinutritional compounds compared with the control sample (p ≤ 0.05), among which S4 (i.e., treated at 60 kV for 10 min) and S2 (i.e., treated at 50 kV for 10 min) samples showed the highest decrease in saponin and phytic acid content, respectively. Also, total phenolic content and antioxidant capacity (DPPH and FRAP) of ACP-treated samples have decreased compared with the control sample. The flavonoid content of ACP-treated samples has been increased compared with the control sample (p ≤ 0.05). In general, the S4 (at 60 kV for 10 min) samples had the highest amount of flavonoid and phenolic content compared with the other samples. A significant reduction in TBAR values has been observed by ACP treatment with the maximum reduction at S4 (i.e., treated at 60 kV for 10 min) samples. Results indicated that ACP treatment at 60 KV for 10 min is effective to reduce the antinutritional compounds and maintain the antioxidant compounds of quinoa grains as well. Considering the necessity of keeping the nutritional characteristics of grains through processing, it needs to be monitored and optimized the condition in a way that nutritional characteristics are preserved.

On-going issues regarding biofilm formation in meat and meat products: challenges and future perspectives

The meat industry has been significantly threatened by the risks of foodborne microorganisms and biofilm formation on fresh meat and processed products. A microbial biofilm is a sophisticated defensive mechanism that enables bacterial cells to survive in unfavorable environmental circumstances. Generally, foodborne pathogens form biofilms in various areas of meat-processing plants, and adequate sanitization of these areas is challenging owing to the high tolerance of biofilm cells to sanitization compared with their planktonic states. Consequently, preventing biofilm initiation and maturation using effective and powerful technologies is imperative. In this review, novel and advanced technologies that prevent bacterial and biofilm development via individual and combined intervention technologies, such as ultrasound, cold plasma, enzymes, bacteriocins, essential oils, and phages, were evaluated. The evidence regarding current technologies revealed in this paper is potentially beneficial to the meat industry in preventing bacterial contamination and biofilm formation in food products and processing equipment.

The challenges and prospects of using cold plasma to prevent bacterial contamination and biofilm formation in the meat industry

The risk of foodborne disease outbreaks increases when the pathogenic bacteria are able to form biofilms, and this presents a major threat to public health. An emerging non-thermal cold plasma (CP) technology has proven a highly effective method for decontaminating meats and their products and extended their shelf life. CP treatments have ability to reduce microbial load and, biofilm formation with minimal change of color, pH value, and lipid oxidation of various meat and meat products. The CP technique offers many advantages over conventional processing techniques due to its layout flexibility, nonthermal behavior, affordability, and ecological sustainability. The technology is still in its infancy, and continuous research efforts are needed to realize its full potential in the meat industry. This review addresses the basic principles and the impact of CP technology on biofilm formation, meat quality (including microbiological, color, pH value, texture, and lipid oxidation), and microbial inactivation pathways and also the prospects of this technology.

Versatile dielectric barrier discharge cold plasma for safety and quality control in fruits and vegetables products: Principles, configurations and applications

It is well-known that fresh fruits and vegetables and their products are particularly susceptible to microbial contaminations. Seeking safer and more effective methods and technologies to extend the shelf life of these foods and ensure their safety is obviously important. This review comprehensively discusses the applications of versatile dielectric barrier discharge (DBD) cold plasma technology in the safety control and shelf-life extension of fruits and vegetables. The effectiveness of DBD cold plasma in microbial purification, the capacity for pesticide residue degradation, and the influence on the sensory and nutritional attributes of fruits and vegetables products are detailly reported. Additionally, the review discusses the challenges of scaling DBD from experimental setups to industrial applications, including technical hurdles, commercial feasibility, and the need for rigorous safety evaluations and monitoring protocols. This review aims to provide recommendations for the ongoing development of food safety and quality measures in the fresh fruits and vegetables and their processing products.

Experimental Investigation of Bacterial Inactivation of Beef Using Indirect Cold Plasma in Cold Chain and at Room Temperature

Pathogen contamination is a severe problem in maintaining food safety in the cold chain. Cold plasma (CP) is a novel non-thermal disinfection method that can be applied for the bacterial inactivation of food in appropriate contexts. Currently, research on CP used on food at cold chain temperatures is rare. This work investigated the bacterial inactivation effect of CP on beef at typical cold storage temperatures of 4 and -18 °C and room temperature (25 °C). The reactive species in CP were indirectly tested by evaluating O3, NO3- and NO2- in cold plasma-activated water (PAW), which indicated the highest concentrations of reactive species in CP at 25 °C and the lowest at -18 °C. The bactericidal efficacy of CP treatment against beef inoculated with Escherichia coli at -18 °C, 4 °C, and 25 °C was 30.5%, 60.1%, and 59.5%, respectively. The 4 °C environment was the most appropriate treatment for CP against beef, with the highest bactericidal efficacy and a minor influence on beef quality. The indirect CP treatment had no significant effect on the texture, color, pH, or cooking loss of beef at -18 °C. CP shows significant potential for the efficient decontamination of food at cold chain temperatures.

Current Status of Non-Thermal Sterilization by Pet Food Raw Ingredients

Recently, as the concept of pet food that satisfies both nutritional needs and the five senses has evolved, so too has the demand for effective pet food non-thermal sterilization methods. Prominent non-thermal technologies include high-pressure processing, plasma, and radiation, which are favored for their ability to preserve nutrients, avoid residues, and minimize compositional changes, thereby maintaining quality and sensory properties. However, to assess their effectiveness on pet food, it is essential to optimize operational parameters such as pressure levels, plasma intensity, radiation dosage, and temperature. Further studies are needed to evaluate microbial sterilization efficacy and sensory attributes. This exploration is expected to lay the groundwork for preventing zoonotic diseases and improving the production of high-quality pet food.

Combined of plasma-activated water and dielectric barrier discharge atmospheric cold plasma treatment improves the characteristic flavor of Asian sea bass (Lates calcarifer) through facilitating lipid oxidation

To explore the combination effects of plasma-activated water and dielectric barrier discharge (PAW-DBD) cold plasma treatment on the formation of volatile flavor and lipid oxidation in Asian sea bass (ASB), the volatile flavor compounds and lipid profiles were characterized by gas chromatography-ion mobility spectrometry and LC-MS-based lipidomics analyses. In total, 38 volatile flavor compound types were identified, and the PAW-DBD group showed the most kinds of volatile components with a significant (p < 0.05) higher content in aldehydes, ketones, and alcohols. A total of 1500 lipids was detected in lipidomics analysis, phosphatidylcholine was the most followed by triglyceride. The total saturated fatty acids content in PAW-DBD group increased by 105.02 μg/g, while the total content of unsaturated fatty acids decreased by 275.36 μg/g. It can be concluded that the PAW-DBD processing increased both the types and amounts of the volatile flavor in ASB and promoted lipid oxidation by altering lipid profiles.

Protecting meat color: The interplay of betanin red and myoglobin through antioxidation and coloration

Myoglobin (Mb) responsible for meat color is easily oxidized resulting in meat discoloration. Here, betanin red (BR), as a natural pigment and antioxidant, was chosen for enhancing redness and inhibiting oxidation. Multiple spectroscopies, isothermal titration calorimetry and molecular docking demonstrated that BR changed the microenvironment of heme group and amino acid residues of Mb, inhibited the oxidation of oxymyoglobin. The main interaction force was hydrogen bond and one variable binding site provided a continuous protective barrier to realize antioxidation. The combination of antioxidation with the inherent red color of BR offered dual color protection effect on processed beef with the addition amount of 0.2 % BR. BR treatment enhanced the redness by 25.59 ∼ 53.24 % and the sensory acceptance by 4.89 ∼ 14.24 %, and decreased the lipid oxidation by 0.58 ∼ 15.92 %. This study paves a theoretical basis for the application of BR and its structural analogues in meat color protection and other quality improvement.

Lc-ms-based lipidomics analyses revealed changes in lipid profiles in Asian sea bass (Lates calcarifer) with dielectric barrier discharge (DBD) atmospheric plasma treatment

A comprehensive LC-MS-based lipidomics analysis of Asian sea bass (Lates calcarifer) muscle after dielectric barrier discharge (DBD) atmospheric plasma treatment was performed. Through the analysis, 1500 lipid species were detected, phosphatidylcholine (PC, 27.80%) was the most abundant lipid, followed by triglyceride (TG, 20.50%) and phosphatidylethanolamine (PE, 17.10%). Among them, 125 lipid species were detected and identified as differentially abundant lipids in Asian sea bass (ASB). PCA and OPLS-DA showed that ASB lipids changed significantly after DBD treatment. Moreover, glycerophospholipid metabolism was key metabolic pathways, as PC, PE, and lysophosphatidylcholine (LPC) were key lipid metabolites. The findings concerning fatty acids revealed that the saturated fatty acids (SFA) content of ASB after DBD treatment increased by 8.54%, while the content of monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA) decreased by 13.77% and 9.16%, respectively. Our study establishes a foundation for the lipid oxidation mechanism of ASB following DBD treatment.

Mechanism of inactivation of Aspergillus flavus spores by dielectric barrier discharge plasma

Dielectric barrier discharge plasma (DBDP) displays strong against fungal spores, while its precise mechanism of spore inactivation remains inadequately understood. In this study, we applied morphological, in vivo and in vitro experiments, transcriptomics, and physicochemical detection to unveil the potential molecular pathways underlying the inactivation of Aspergillus flavus spores by DBDP. Our findings suggested that mycelium growth was inhibited as observed by SEM after 30 s treatment at 70 kV, meanwhile spore germination ceased and clustering occurred. It led to the release of cellular contents and subsequent spore demise by disrupting the integrity of spore membrane. Additionally, based on the transcriptomic data, we hypothesized that the induction of spore inactivation by DBDP might be associated with downregulation of genes related to cell membranes, organelles (mitochondria), oxidative phosphorylation, and the tricarboxylic acid cycle. Subsequently, we validated our transcriptomic findings by measuring the levels of relevant enzymes in metabolic pathways, such as superoxide dismutase, acetyl-CoA, total dehydrogenase, and ATP. These physicochemical indicators revealed that DBDP treatment resulted in mitochondrial dysfunction, redox imbalance, and inhibited energy metabolism pathways. These findings were consistent with the transcriptomic results. Hence, we concluded that DBDP accelerated spore rupture and death via ROS-mediated mitochondrial dysfunction, which does not depend on cell membranes.

Effect of novel and conventional food processing technologies on Bacillus cereus spores

This chapter provides a summary of the effect of thermal and non-thermal processing technologies on Bacillus cereus spores, a well-known pathogenic bacterium associated with foodborne illnesses. B. cereus has been frequently detected in rice, milk products, infant food, liquid eggs products and meat products all over the world. This Gram positive, rod-shaped, facultative anaerobe can produce endospores that can withstand pasteurization, UV radiation, and chemical reagents commonly used for sanitization. B. cereus spores can germinate into vegetative cells that can produce toxins. The conventional regime for eliminating spores from food is retorting which uses the application of high temperature (121 °C). However, at this temperature, there could be a significant amount of loss in the organoleptic and functional qualities of the food components, especially proteins. This leads to the research on the preventive measures against germination and if possible, to reduce the resistance before using a non-thermal technology (temperatures less than retorting-121 °C) for inactivation. This chapter reviews the development and success of several food processing technologies in their ability to inactivate B. cereus spores in food.

Innovative Application of Cold Plasma Technology in Meat and Its Products

The growing demand for sustainable food production and the rising consumer preference for fresh, healthy, and safe food products have been driving the need for innovative methods for processing and preserving food. In the meat industry, this demand has led to the development of new interventions aimed at extending the shelf life of meats and its products while maintaining their quality and nutritional value. Cold plasma has recently emerged as a subject of great interest in the meat industry due to its potential to enhance the microbiological safety of meat and its products. This review discusses the latest research on the possible application of cold plasma in the meat processing industry, considering its effects on various quality attributes and its potential for meat preservation and enhancement. In this regard, many studies have reported substantial antimicrobial efficacy of cold plasma technology in beef, pork, lamb and chicken, and their products with negligible changes in their physicochemical attributes. Further, the application of cold plasma in meat processing has shown promising results as a potential novel curing agent for cured meat products. Understanding the mechanisms of action and the interactions between cold plasma and food ingredients is crucial for further exploring the potential of this technology in the meat industry, ultimately leading to the development of safe and high-quality meat products using cold plasma technology.

Insight into the microorganisms, quality, and protein structure of golden pompano (Trachinotus ovatus) treated with cold plasma at different voltages

Cold plasma (CP) is a non-thermal novel technology for the processing of heat-sensitive food products, but there is concern regarding its impact on food quality. Voltage is one of the most direct factors affecting the bacteriostatic effect of CP. Golden pompano (Trachinotus ovatus) was treated with CP at different voltages (10, 20, and 30 kV). The total viable count decreased as the CP voltage increased, reaching a maximum reduction of 1.54 lg CFU/g on golden pompano treated at 30 kV. No effects on water-holding capacity, pH, total volatile base nitrogen, and T_2b relaxation time were observed, indicating that all CP treatments retained the freshness and bound water of the samples. However, as the CP voltage increased, peroxide value and thiobarbituric acid-reactive substances of golden pompano gradually increased, the protein tertiary structure unfolded, and α-helices converted to β-sheets, indicating inevitable lipid and protein oxidation caused by excessive CP voltage. Therefore, a suitable voltage of CP should be selected to inhibits the growth of microorganisms, which avoids deterioration of sea-foods quality.

Current and Potential Applications of Atmospheric Cold Plasma in the Food Industry

The cost-effectiveness and high efficiency of atmospheric cold plasma (ACP) incentivise researchers to explore its potentials within the food industry. Presently, the destructive nature of this nonthermal technology can be utilised to inactivate foodborne pathogens, enzymatic ripening, food allergens, and pesticides. However, by adjusting its parameters, ACP can also be employed in other novel applications including food modification, drying pre-treatment, nutrient extraction, active packaging, and food waste processing. Relevant studies were conducted to investigate the impacts of ACP and posit that reactive oxygen and nitrogen species (RONS) play the principal roles in achieving the set objectives. In this review article, operations of ACP to achieve desired results are discussed. Moreover, the recent progress of ACP in food processing and safety within the past decade is summarised while current challenges as well as its future outlook are proposed.

Cold plasma pretreatment reinforces the lignocellulose-derived aldehyde inhibitors tolerance and bioethanol fermentability for Zymomonas mobilis

BACKGROUND

Lignocellulose-derived aldehyde inhibitors seriously blocked the biorefinery of biofuels and biochemicals. To date, the economic production of lignocellulose-based products heavily relied on high productivities of fermenting strains. However, it was expensive and time-consuming for the achievable rational modification to strengthen stress tolerance robustness of aldehyde inhibitors. Here, it aimed to improve aldehyde inhibitors tolerance and cellulosic bioethanol fermentability for the chassis Zymomonas mobilis ZM4 pretreated using energy-efficient and eco-friendly cold plasma.

RESULTS

It was found that bioethanol fermentability was weaker in CSH (corn stover hydrolysates) than that in synthetic medium for Z. mobilis, and thus was attributed to the inhibition of the lignocellulose-derived aldehyde inhibitors in CSH. Convincingly, it further confirmed that the mixed aldehydes severely decreased bioethanol accumulation through additional aldehydes supplementary assays in synthetic medium. After assayed under different processing time (10-30 s), discharge power (80-160 W), and working pressure (120-180 Pa) using cold atmosphere plasma (CAP), it achieved the increased bioethanol fermentability for Z. mobilis after pretreated at the optimized parameters (20 s, 140 W and 165 Pa). It showed that cold plasma brought about three mutation sites including ZMO0694 (E220V), ZMO0843 (L471L) and ZMO0843 (P505H) via Genome resequencing-based SNPs (single nucleotide polymorphisms). A serial of differentially expressed genes (DEGs) were further identified as the potential contributors for stress tolerance via RNA-Seq sequencing, including ZMO0253 and ZMO_RS09265 (type I secretion outer membrane protein), ZMO1941 (Type IV secretory pathway protease TraF-like protein), ZMOr003 and ZMOr006 (16S ribosomal RNA), ZMO0375 and ZMO0374 (levansucrase) and ZMO1705 (thioredoxins). It enriched cellular process, followed by metabolic process and single-organism process for biological process. For KEGG analysis, the mutant was also referred to starch and sucrose metabolism, galactose metabolism and two-component system. Finally, but interestingly, it simultaneously achieved the enhanced stress tolerance capacity of aldehyde inhibitors and bioethanol fermentability in CSH for the mutant Z. mobilis.

CONCLUSIONS

Of several candidate genetic changes, the mutant Z. mobilis treated with cold plasma was conferred upon the facilitated aldehyde inhibitors tolerance and bioethanol production. This work would provide a strain biocatalyst for the efficient production of lignocellulosic biofuels and biochemicals.

Using TRIS-Buffered Plasma-Activated Water to Reduce Pathogenic Microorganisms on Poultry Carcasses with Evaluation of Physicochemical and Sensory Parameters

Foodborne diseases are mainly caused by the contamination of meat or meat products with pathogenic microorganisms. In this study, we first investigated the in vitro application of TRIS-buffered plasma-activated water (Tb-PAW) on Campylobacter (C.) jejuni and Escherichia (E.) coli, with a reduction of approx. 4.20 ± 0.68 and 5.12 ± 0.46 log₁₀ CFU/mL. Furthermore, chicken and duck thighs (inoculated with C. jejuni or E. coli) and breasts (with natural microflora) with skin were sprayed with Tb-PAW. Samples were packed under a modified atmosphere and stored at 4 °C for 0, 7, and 14 days. The Tb-PAW could reduce C. jejuni on days 7 and 14 (chicken) and E. coli on day 14 (duck) significantly. In chicken, there were no significant differences in sensory, pH-value, color, and antioxidant activity, but %OxyMb levels decreased, whereas %MetMb and %DeoMb increased. In duck, we observed slight differences in pH-value, color, and myoglobin redox forms for the Tb-PAW, which were not perceived by the sensory test persons. With only slight differences in product quality, its application as a spray treatment may be a useful method to reduce C. jejuni and E. coli on chicken and duck carcasses.

Surface dielectric barrier discharge plasma-treated pork cut parts: bactericidal efficacy and physiochemical characteristics

Maintaining agro-food product safety remains a significant challenge for satisfying local and global consumers in tropical countries. This issue has been growing due to new pathogen strains, low infectious doses, increased virulence, antibiotic resistance, cross-contamination or recontamination of foods, food-contact surfaces, and biocontamination of water within the food production chain. To respond to this situation, we studied the inactivation efficacy of surface dielectric barrier discharge (SDBD) plasma against pathogens on the surface of various pork cut parts, including the loin, hip, belly, liver, and intestine. The SDBD plasma was operated at 0.30 W/cm² in ambient air, with a gap of 5.0 mm between the plasma generator and the sample surface. Up to 96% germicidal efficiency against surface pathogens were observed, showing after 1 min of SDBD plasma exposure. Visualization of reactive species deposition on the treated surface using KI-starch agar gel reagent indicated a non-uniform distribution of the SDBD-generated reactive species on the treated surface. Following the indirect plasma treatment by the SDBD reactor, the overall color of pork cut samples after plasma treatment was significantly different compared with before. However, the surface morphology and structural characterization of the treated pork cut samples were not significantly altered, and residual nitrites and nitrates were lower than the restriction level for safe consumption. The SDBD reactor should be developed further to produce a uniform distribution of reactive species on the meat surface for the improvement of the decontamination effect without undesirable effects on meat quality parameters.

Processing interventions for enhanced microbiological safety of beef carcasses and beef products: A review

Chilled beef is inevitably contaminated with microorganisms, starting from the very beginning of the slaughter line. A lot of studies have aimed to improve meat safety and extend the shelf life of chilled beef, of which some have focused on improving the decontamination effects using traditional decontamination interventions, and others have investigated newer technologies and methods, that offer greater energy efficiency, lower environmental impacts, and better assurances for the decontamination of beef carcasses and cuts. To inform industry, there is an urgent need to review these interventions, analyze the merits and demerits of each technology, and provide insight into 'best practice' to preserve microbial safety and beef quality. In this review, the strategies and procedures used to inhibit the growth of microorganisms on beef, from slaughter to storage, have been critiqued. Critical aspects, where there is a lack of data, have been highlighted to help guide future research. It is also acknowledge that different intervention programs for microbiological safety have different applications, dependent on the initial microbial load, the type of infrastructures, and different stages of beef processing.

Effects of High Voltage Atmospheric Cold Plasma Treatment on the Number of Microorganisms and the Quality of Trachinotus ovatus during Refrigerator Storage

In order to investigate the effects of high voltage atmospheric cold plasma (HVACP) treatment on the number of microorganisms in and the quality of Trachinotus ovatus during refrigerator storage, fresh fish was packaged with gases CO2:O2:N2 (80%:10%:10%) and treated by HVACP at 75 kV for 3 min; then, the samples were stored at 4 ± 1 °C for nine days. The microbial numbers, water content, color value, texture, pH value, thiobarbituric acid reactive substance (TBARS), and total volatile base nitrogen (TVB-N) values of the fish were analyzed during storage. The results showed the growth of the total viable bacteria (TVB), psychrophilic bacteria, Pseudomonas spp., H2S-producing bacteria, yeast, and lactic acid bacteria in the treated samples was limited, and they were 1.11, 1.01, 1.04, 1.13, 0.77, and 0.80 log CFU/g-1 lower than those in the control group after nine days of storage, respectively. The hardness, springiness, and chewiness of the treated fish decreased slowly as the storage time extended, and no significant changes in either pH or water content were found. The lightness (L*) value increased and the yellowness (b*) value decreased after treatment, while no changes in the redness (a*) value were found. The TBARS and TVB-N of the treated samples increased to 0.79 mg/kg and 21.99 mg/100 g, respectively, after nine days of refrigerator storage. In conclusion, HVACP can limit the growth of the main microorganisms in fish samples effectively during nine days of refrigerator storage with no significant negative impact on their quality. Therefore, HVACP is a useful nonthermal technology to extend the refrigerator shelf-life of Trachinotus ovatus.

Thermal treatment alternatives for enzymes inactivation in fruit juices: Recent breakthroughs and advancements

Fruit juices (FJs) are frequently taken owing to their nutritious benefits, appealing flavour, and vibrant colour. The colours of the FJs are critical indicators of the qualitative features that influence the consumer's attention. Although FJs' intrinsic acidity serves as a barrier to bacterial growth, their enzymatic stability remains an issue for their shelf life. Inactivation of enzymes is critical during FJ processing, and selective inactivation is the primary focus of enzyme inactivation. The merchants, on the other hand, want the FJs to stay stable. The most prevalent technique of processing FJ is by conventional heat treatment, which degrades its nutritive value and appearance. The FJ processing industry has undergone a dramatic transformation from thermal treatments to nonthermal treatments (NTTs) during the past two decades to meet the requirements for microbiological and enzymatic stability. The manufacturers want safe and stable FJs, while buyers want high-quality FJs. According to the past investigation, NTTs have the potential to manufacture microbiologically safe and enzymatically stable FJs with low loss of bioactive components. Furthermore, it has been demonstrated that different NTTs combined with or without other NTTs or mild heating as a hurdle technology increase the synergistic effect for microbiological safety and stability of FJs. Concise information about the variables that affect NTTs' action mode has also been addressed. Primary inactivates enzymes by modifying the protein structure and active site conformation. NTTs may increase enzyme activity depending on the nature of the enzyme contained in FJs, the applied pressure, pH, temperature, and treatment period. This is due to the release of membrane-bound enzymes as well as changes in protein structure and active sites that allow substrate interaction. Additionally, the combination of several NTTs as a hurdle technology, as well as temperature and treatment periods, resulted in increased enzyme inactivation in FJs. Therefore, a combination of thermal and non-thermal technologies is suggested to increase the effectiveness of the process as well as preserve the juice quality.

Microbial Inactivation Property of Pulsed Corona Discharge Plasma and Its Effect on Chilled Pork Preservation

Although plasma, especially atmospheric plasma generated by corona discharge, has been proven to be effective in sterilization and food preservation, its disinfection mechanism on chilled pork is poorly understood. In this research, the bactericidal and preservation effect of corona discharge plasma (CDP) was investigated. The maximum bactericidal effect was found after 20 kV 4 kHz CDP treatment, with 2.77 log (colony-forming unit [CFU]/g), 2.41 log (CFU/g), and 1.36 log (CFU/g) reduction for Pantoea agglomerans, Serratia liquefaciens, and Kurthia zopfii, respectively, after 10 min of exposure. The efficiency of microbial inactivation was attributed to the increase of ozone, hydrogen peroxide and morphological changes. It was observed that the microbial level and total volatile binding nitrogen value of CDP-treated chilled pork samples were suppressed during storage, whereas the increase of thiobarbituric acid reactive substances value and the changes of color were still worthy of attention. The aim of this study was to explore the effect of pulsed CDP on the inactivation of spoilage microorganism inoculated on the surface of fresh pork. The prospect of this technology in meat preservation industry was also investigated.

Recent developments in cold plasma-based enzyme activity (browning, cell wall degradation, and antioxidant) in fruits and vegetables

According to the Food and Agriculture Organization of United Nations reports, approximately half of the total harvested fruits and vegetables vanish before they reach the end consumer due to their perishable nature. Enzymatic browning is one of the most common problems faced by fruit and vegetable processing. The perishability of fruits and vegetables is contributed by the various browning enzymes (polyphenol oxidase, peroxidase, and phenylalanine ammonia-lyase) and ripening or cell wall degrading enzyme (pectin methyl-esterase). In contrast, antioxidant enzymes (superoxide dismutase and catalase) assist in reversing the damage caused by reactive oxygen species or free radicals. The cold plasma technique has emerged as a novel, economic, and environmentally friendly approach that reduces the expression of ripening and browning enzymes while increasing the activity of antioxidant enzymes; microorganisms are significantly inhibited, therefore improving the shelf life of fruits and vegetables. This review narrates the mechanism and principle involved in the use of cold plasma technique as a nonthermal agent and its application in impeding the activity of browning and ripening enzymes and increasing the expression of antioxidant enzymes for improving the shelf life and quality of fresh fruits and vegetables and preventing spoilage and pathogenic germs from growing. An overview of hurdles and sustainability advantages of cold plasma technology is presented.

Characterisation of Flavour Attributes in Egg White Protein Using HS-GC-IMS Combined with E-Nose and E-Tongue: Effect of High-Voltage Cold Plasma Treatment Time

Egg white protein (EWP) is susceptible to denaturation and coagulation when exposed to high temperatures, adversely affecting its flavour, thereby influencing consumers' decisions. Here, we employ high-voltage cold plasma (HVCP) as a novel nonthermal technique to investigate its influence on the EWP's flavour attributes using E-nose, E-tongue, and headspace gas-chromatography-ion-mobilisation spectrometry (HS-GC-IMS) due to their rapidness and high sensitivity in identifying flavour fingerprints in foods. The EWP was investigated at 0, 60, 120, 180, 240, and 300 s of HVCP treatment time. The results revealed that HVCP significantly influences the odour and taste attributes of the EWP across all treatments, with a more significant influence at 60 and 120 s of HVCP treatment. Principal component analyses of the E-nose and E-tongue clearly distinguish the odour and taste sensors' responses. The HS-GC-IMS analysis identified 65 volatile compounds across the treatments. The volatile compounds' concentrations increased as the HVCP treatment time was increased from 0 to 300 s. The significant compounds contributing to EWP characterisation include heptanal, ethylbenzene, ethanol, acetic acid, nonanal, heptacosane, 5-octadecanal, decanal, p-xylene, and octanal. Thus, this study shows that HVCP could be utilised to modify and improve the EWP flavour attributes.

Applications of Cold Atmospheric Pressure Plasma Technology in Medicine, Agriculture and Food Industry

In recent years, cold atmospheric pressure plasma (CAPP) technology has received substantial attention due to its valuable properties including operational simplicity, low running cost, and environmental friendliness. Several different gases (air, nitrogen, helium, argon) and techniques (corona discharge, dielectric barrier discharge, plasma jet) can be used to generate plasma at atmospheric pressure and low temperature. Plasma treatment is routinely used in materials science to modify the surface properties (e.g., wettability, chemical composition, adhesion) of a wide range of materials (e.g., polymers, textiles, metals, glasses). Moreover, CAPP seems to be a powerful tool for the inactivation of various pathogens (e.g., bacteria, fungi, viruses) in the food industry (e.g., food and packing material decontamination, shelf life extension), agriculture (e.g., disinfection of seeds, fertilizer, water, soil) and medicine (e.g., sterilization of medical equipment, implants). Plasma medicine also holds great promise for direct therapeutic treatments in dentistry (tooth bleaching), dermatology (atopic eczema, wound healing) and oncology (melanoma, glioblastoma). Overall, CAPP technology is an innovative, powerful and effective tool offering a broad application potential. However, its limitations and negative impacts need to be determined in order to receive regulatory approval and consumer acceptance.