Cold plasma for mitigating agrochemical and pesticide residue in food and water: Similarities with ozone and ultraviolet technologies

Cold atmospheric plasma inactivation of polyphenol oxidase: Focus on the protective and boosting effect of mono- and disaccharides

Polyphenol oxidase (PPO) is among the most detrimental enzymes in processed plant foods, being responsible for enzymatic browning. To propose a "mild" alternative to traditional enzymatic inactivation methods, this study investigated the effect of cold atmospheric plasma (CAP) on PPO inactivation and highlighted the role of different sugars on both inactivation and structural modification of this enzyme. Different model systems were prepared in phosphate buffer using a purified PPO either alone or added with glucose, fructose, sucrose, and trehalose at different concentrations. CAP treatments (6 KV; 23 KHz; duty cycle 10%) were applied at times ranging from 5 to 30 min. Different spectroscopic analyses were conducted before and after treatments to evaluate the PPO activity and changes in tertiary and secondary structures. CAP induced a significant reduction (p < 0.05) in PPO activity across all systems, ranging from 70% to 94% after 30 min of treatment. Among sugars, fructose enhanced (p < 0.05) the PPO inactivation (+23% on average with respect to the phosphate buffer system), possibly by promoting the loss of secondary structures containing the copper-binding site of the catalytic pocket. The effect of other sugars on PPO inactivation was strictly dependent on their type and concentration; specifically, disaccharides at the highest concentrations and treatment times showed a protective effect on the structure and functionality of the protein. Thus, the results of this study highlight that sugars can modulate the effectiveness of CAP, offering promising perspectives for optimizing this food processing technology. PRACTICAL APPLICATION: Cold atmospheric plasma (CAP) is a promising nonthermal technology for food preservation. In particular, surface dielectric barrier discharge (SDBD) CAP could be applied as an alternative to chemical and thermal treatments to inactivate polyphenol oxidase (PPO), an enzyme responsible for browning reactions and quality loss in most processed fruit and vegetable products. However, as shown by this study, PPO inactivation induced by CAP is affected by sugars. Specifically, fructose can positively influence the inactivation of this enzyme. Therefore, CAP potentially could find main applications for the PPO stabilization of high fructose-content plants (e.g., pears, apples, bananas, grapes, peppers, and squashes).

Bioaerosol Inactivation by a Cold Plasma Ionizer Coupled with an Electrostatic Precipitator

Despite best efforts in air purification, airborne infectious diseases will continue to spread due to the continuous emission of bioaerosols by the host/infected person. Hence, a shift in focus from air purification to bioaerosol inactivation is urgently needed. To explore the potential of the cold plasma technology for preventing rapid spread of airborne infectious diseases, we studied a cold plasma ionizer (CPI) device and an electrostatic precipitator (ESP)-coupled CPI (CPI-ESP) device for the inactivation and cleaning of surface-spread microorganisms and bioaerosols, using porcine respiratory coronavirus (PRCV), Escherichia coli (E. coli), and aerosolized E. coli as representatives. We firstly demonstrated that CPI coupled with ESP is an effective technology for inactivating virus and bacteria spread on surfaces in an in-house test chamber. We then demonstrated the efficacy of CPI-coupled ESP for the inactivation of aerosolized E. coli in the same chamber. Furthermore, we have demonstrated the efficiency of a CPI-ESP coupled device for the inactivation of naturally occurring airborne microbials in a few indoor settings (i.e., a living room, a discussion room, a schoolroom, and an office) to determine the treatment duration- and human activity-dependent efficacy. To understand the disinfection mechanism, we conducted a fluorescence microscopy study to reveal different degrees of E. coli bacteria cell membrane damage under CPI treatment.

Insights into Cold Plasma Treatment on the Cereal and Legume Proteins Modification: Principle, Mechanism, and Application

Cereal and legume proteins, pivotal for human health, significantly influence the quality and stability of processed foods. Despite their importance, the inherent limited functional properties of these natural proteins constrain their utility across various sectors, including the food, packaging, and pharmaceutical industries. Enhancing functional attributes of cereal and legume proteins through scientific and technological interventions is essential to broadening their application. Cold plasma (CP) technology, characterized by its non-toxic, non-thermal nature, presents numerous benefits such as low operational temperatures, lack of external chemical reagents, and cost-effectiveness. It holds the promise of improving proteins' functionality while maximally retaining their nutritional content. This review delves into the pros and cons of different cold plasma generation techniques, elucidates the underlying mechanisms of protein modification via CP, and thoroughly examines research on the application of cold plasma in augmenting the functional properties of proteins. The aim is to furnish theoretical foundations for leveraging CP technology in the modification of cereal and legume proteins, thereby enhancing their practical applicability in diverse industries.

From field to table: Ensuring food safety by reducing pesticide residues in food

The present review addresses the significance of lowering pesticide residue levels in food items because of their harmful impacts on human health, wildlife populations, and the environment. It draws attention to the possible health risks-acute and chronic poisoning, cancer, unfavorable effects on reproduction, and harm to the brain or immunological systems-that come with pesticide exposure. Numerous traditional and cutting-edge methods, such as washing, blanching, peeling, thermal treatments, alkaline electrolyzed water washing, cold plasma, ultrasonic cleaning, ozone treatment, and enzymatic treatment, have been proposed to reduce pesticide residues in food products. It highlights the necessity of a paradigm change in crop protection and agri-food production on a global scale. It offers opportunities to guarantee food safety through the mitigation of pesticide residues in food. The review concludes that the first step in reducing worries about the negative effects of pesticides is to implement regulatory measures to regulate their use. In order to lower the exposure to dietary pesticides, the present review also emphasizes the significance of precision agricultural practices and integrated pest management techniques. The advanced approaches covered in this review present viable options along with traditional methods and possess the potential to lower pesticide residues in food items without sacrificing quality. It can be concluded from the present review that a paradigm shift towards sustainable agriculture and food production is essential to minimize pesticide residues in food, safeguarding human health, wildlife populations, and the environment. Furthermore, there is a need to refine the conventional methods of pesticide removal from food items along with the development of modern techniques.

Effective Removal of Different Heavy Metals Ion (Cu, Pb, and Cd) from Aqueous Solutions by Various Molecular Weight and Salt Types of Poly-γ-Glutamic Acid

In light of industrial developments, water pollution by heavy metals as hazardous chemicals has garnered attention. Addressing the urgent need for efficient heavy metal removal from aqueous environments, this study delves into using poly-γ-glutamic acid (γ-PGA) for the bioflocculation of heavy metals. Utilizing γ-PGA variants from Bacillus subtilis with different molecular weights and salt forms (Na-bonded and Ca-bonded), the research evaluates their adsorption capacities for copper (Cu), lead (Pb), and cadmium (Cd) ions. It was found that Na-bonded γ-PGA with a high molecular weight showed the highest heavy metal adsorption (92.2-98.3%), particularly at a 0.5% concentration which exhibited the highest adsorption efficiency. Additionally, the study investigated the interaction of γ-PGA in mixed heavy metal environments, and it was discovered that Na-γ-PGA-HM at a 0.5% concentration showed a superior adsorption efficiency for Pb ions (85.4%), highlighting its selectivity as a potential effective biosorbent for wastewater treatment. This research not only enlightens the understanding of γ-PGA's role in heavy metal remediation but also underscores its potential as a biodegradable and non-toxic alternative for environmental cleanup. The findings pave the way for further exploration into the mechanisms and kinetics of γ-PGA's adsorption properties.

Bacterial Decontamination of Water-Containing Objects Using Piezoelectric Direct Discharge Plasma and Plasma Jet

Cold atmospheric plasma has become a widespread tool in bacterial decontamination, harnessing reactive oxygen and nitrogen species to neutralize bacteria on surfaces and in the air. This technology is often employed in healthcare, food processing, water treatment, etc. One of the most energy-efficient and universal methods for creating cold atmospheric plasma is the initiation of a piezoelectric direct discharge. The article presents a study of the bactericidal effect of piezoelectric direct discharge plasma generated using the multifunctional source "CAPKO". This device allows for the modification of the method of plasma generation "on the fly" by replacing a unit (cap) on the working device. The results of the generation of reactive oxygen and nitrogen species in a buffer solution in the modes of direct discharge in air and a plasma jet with an argon flow are presented. The bactericidal effect of these types of plasma against the bacteria E. coli BL21 (DE3) was studied. The issues of scaling the treatment technique are considered.

Degradation of Pesticide Residues in Water, Soil, and Food Products via Cold Plasma Technology

Water, soil, and food products contain pesticide residues. These residues result from excessive pesticides use, motivated by the fact that agricultural productivity can be increased by the use of these pesticides. The accumulation of these residues in the body can cause health problems, leading to food safety concerns. Cold plasma technology has been successfully employed in various applications, such as seed germination, bacterial inactivation, wound disinfection, surface sterilization, and pesticide degradation. In recent years, researchers have increasingly explored the effectiveness of cold plasma technology in the degradation of pesticide residues. Most studies have shown promising outcomes, encouraging further research and scaling-up for commercialization. This review summarizes the use of cold plasma as an emerging technology for pesticide degradation in terms of the plasma system and configuration. It also outlines the key findings in this area. The most frequently adopted plasma systems for each application are identified, and the mechanisms underlying pesticide degradation using cold plasma technology are discussed. The possible factors influencing pesticide degradation efficiency, challenges in research, and future trends are also discussed. This review demonstrates that despite the nascent nature of the technology, the use of cold plasma shows considerable potential in regards to pesticide residue degradation, particularly in food applications.

Enhancing Bioactivity and Conjugation in Green Coffee Bean (Coffea arabica) Extract through Cold Plasma Treatment: Insights into Antioxidant Activity and Phenolic-Protein Conjugates

Cold plasma technology is gaining attention as a promising approach to enhancing the bioactivity of plant extracts. However, its impact on green coffee bean extracts (GCBEs) still needs to be explored. In this study, an innovative underwater plasma jet system was employed to investigate the effects of cold plasma on Coffea arabica GCBEs, focusing on the conjugation reflected by the change in composition and bioactivity. The DPPH radical scavenging antioxidant activity exhibited a gradual increase with plasma treatment up to 35 min, followed by a decline. Remarkably, at 35 min, the plasma treatment resulted in a significant 66% increase in the DPPH radical scavenging activity of the GCBE. The total phenolic compound content also displayed a similar increasing trend to the DPPH radical scavenging activity. However, the phenolic profile analysis indicated a significant decrease in chlorogenic acids and caffeine. Furthermore, the chemical composition analysis revealed a decrease in free amino acids, while sucrose remained unchanged. Additionally, the SDS-PAGE results suggested a slight increase in protein size. The observed enhancement in antioxidant activity, despite the reduction in the two major antioxidants in the GCBE, along with the increase in protein size, might suggest the occurrence of conjugation processes induced by plasma, particularly involving proteins and phenolic compounds. Notably, the plasma treatment exhibited no adverse effects on the extract's safety, as confirmed by the MTT assay. These findings indicate that cold plasma treatment holds significant promise in improving the functional properties of GCBE while ensuring its safety. Incorporating cold plasma technology into the processing of natural extracts may offer exciting opportunities for developing novel and potent antioxidant-rich products.

The Effect of Washing, Blanching and Frozen Storage on Pesticide Residue in Spinach

Spinach (Spinacia oleracea L.) is a representative green leafy vegetable commonly consumed fresh or as a ready-to-cook frozen product, with increasing consumption because of its many health-related properties. Among leafy vegetables, spinach poses a major concern in terms of pesticide residue detection due to common phytotechnical practices. In this study, spinach leaves were treated in the open field with three commercial pesticide formulations containing propamocarb, lambda-cyhalothrin, fluopicolide and chlorantraniliprole at the highest concentration. The effects of the successive processing steps of washing, blanching, freezing and frozen storage were evaluated on the levels of the four pesticide residues and the degradation product (propamocarb n-desmethyl). The washing step caused a reduction of fluopicolide and chlorantraniliprole of -47% and -43%, respectively, while having a mild effect on lambda-cyhalothrin content (+5%). A two-minute blanching step allowed for the reduction of pesticides content ranging from -41% to -4% with respect to the washed sample. Different behaviors were depicted for longer blanching times, mainly for propamocarb, reaching -56% after 10 min of treatment. Processing factors higher than 1 were reported mainly for lambda-cyhalothrin and fluopicolide. Frozen storage led to a slight increase in the pesticide content in samples treated for 6 and 10 min. The optimal blanching treatment for spinach, submitted to freezing and frozen storage, seems to be 2 min at 80 °C.

Chemical decontamination of foods using non-thermal plasma-activated water

The presence of chemical contaminants in foods and agricultural products is one of the major safety issues worldwide, posing a serious concern to human health. Nonthermal plasma (NTP) containing richly reactive oxygen and nitrogen species (RONS) has been trialed as a potential decontamination method. Yet, this technology comes with multiple downsides, including adverse effects on the quality of treated foods and limited exposure to entire surfaces on samples with hard-to-reach spots, further hindering real-life applications. Therefore, plasma-activated water (PAW) has been recently developed to facilitate the interactions between RONS and contaminant molecules in the liquid phase, allowing a whole surface treatment with efficient chemical degradation. Here, we review the recent advances in PAW utilized as a chemical decontamination agent in foods. The reaction mechanisms and the main RONS contributors involved in the PAW-assisted removal of chemical contaminants are briefly outlined. Also, the comprehensive effects of these treatments on food qualities (chemical and physical characteristics) and toxicological evaluation of PAW (in vitro and in vivo) are thoroughly discussed. Ultimately, we identified some current challenges and provided relevant suggestions, which can further promote PAW research for real-life applications in the future.

Advances of non-thermal plasma discharge technology in degrading recalcitrant wastewater pollutants. A comprehensive review

With development and urbanization, the amount of wastewater generated due to human activities drastically increases yearly, causing water pollution and intensifying the already worsened water crisis. Although convenient, conventional wastewater treatment methods such as activated sludge, stabilization ponds, and adsorption techniques cannot fully eradicate the complex and recalcitrant contaminants leading to toxic byproducts generation. Recent advancements in wastewater treatment techniques, specifically non-thermal plasma technology, have been extensively investigated for the degradation of complex pollutants in wastewater. Non-thermal plasma is an effective alternative for degrading and augmenting the biodegradability of recalcitrant pollutants due to its ability to generate reactive species in situ. This article critically reviews the non-thermal plasma technology, considering the plasma discharge configuration and reactor types. Furthermore, the influence of operational parameters on the efficiency of the plasma systems and the reactive species generated by the system during discharge has gained significant interest and hence been discussed. Also, the application of non-thermal plasma technology for the degradation of pharmaceuticals, pesticides, and dyes and the inactivation of microbial activities are outlined in this review article. Additionally, optimistic applications involving the combination of non-thermal plasma and catalysts and pilot and industrial-scale projects utilizing non-thermal plasma technology have been addressed. Concluding perceptions on the challenges and future perspectives of the non-thermal technology on wastewater treatment are accentuated. Overall, this review outlines a comprehensive understanding of the non-thermal plasma technology for recalcitrant pollutant degradation from a scientific perspective providing detailed instances for reference.

Efficient Inhibition of Aspergillus flavus to Reduce Aflatoxin Contamination on Peanuts over Ag-Loaded Titanium Dioxide

Peanuts are susceptible to aflatoxins produced by Aspergillus flavus. Exploring green, efficient, and economical ways to inhibit Aspergillus flavus is conducive to controlling aflatoxin contamination from the source. In this study, Ag-loaded titanium dioxide composites showed more than 90% inhibition rate against Aspergillus flavus under visible light irradiation for 15 min. More importantly, this method could also reduce the contaminated level of Aspergillus flavus to prevent aflatoxins production in peanuts, and the concentrations of aflatoxin B1, B2, and G2 were decreased by 96.02 ± 0.19%, 92.50 ± 0.45%, and 89.81 ± 0.52%, respectively. It was found that there are no obvious effects on peanut quality by evaluating the changes in acid value, peroxide value, and the content of fat, protein, polyphenols, and resveratrol after inhibition treatment. The inhibition mechanism was that these reactive species (•O2−, •OH−, h+, and e−) generated from photoreaction destroyed cell structures, then led to the reduced viability of Aspergillus flavus spores. This study provides useful information for constructing a green and efficient inhibition method for Aspergillus flavus on peanuts to control aflatoxin contamination, which is potentially applied in the field of food and agri-food preservation.

Enhanced Gel Properties of Duck Myofibrillar Protein by Plasma-Activated Water: Through Mild Structure Modifications

This study assessed the gel properties and conformational changes of duck myofibrillar protein (DMP) affected by plasma-activated water (PAW) generated at various discharge times (0 s, 10 s, 20 s, 30 s, and 40 s). With the treatment of PAW-20 s, the gel strength and water-holding capacity (WHC) of DMP gels were significantly increased when compared to the control group. Throughout the heating process, dynamic rheology revealed that the PAW-treated DMP had a higher storage modulus than the control. The hydrophobic interactions between protein molecules were significantly improved by PAW, resulting in a more ordered and homogeneous gel microstructure. The increased sulfhydryl and carbonyl content in DMP indicated a higher degree of protein oxidation with PAW treatment. Additionally, the circular dichroism spectroscopy demonstrated that PAW induced α-helix and β-turn transformed to β-sheet in DMP. Surface hydrophobicity, fluorescence spectroscopy, and UV absorption spectroscopy suggested that PAW altered DMP's tertiary structure, although the electrophoretic pattern indicated that the primary structure of DMP was mostly unaffected. These results suggest that PAW can improve the gel properties of DMP through mild alteration in its conformation.

Plasma for aquaponics

Global environmental, social, and economic challenges call for innovative solutions to food production. Current food production systems require advances beyond traditional paradigms, acknowledging the complexity arising from sustainability and a present lack of awareness about technologies that may help limit, for example, loss of nutrients from soil. Aquaponics, a closed-loop system that combines aquaculture with hydroponics, is a step towards the more efficient management of scarce water, land, and nutrient resources. However, its large-scale use is currently limited by several significant challenges of maintaining desirable water chemistry and pH, managing infections in fish and plants, and increasing productivity efficiently, economically, and sustainably. This paper investigates the opportunities presented by plasma technologies in meeting these challenges, potentially opening new pathways for sustainability in food production.

Application of Pinhole Plasma Jet Activated Water against Escherichia coli, Colletotrichum gloeosporioides, and Decontamination of Pesticide Residues on Chili (Capsicum annuum L.)

Plasma activated water (PAW) generated from pinhole plasma jet using gas mixtures of argon (Ar) and 2% oxygen (O2) was evaluated for pesticide degradation and microorganism decontamination (i.e., Escherichia coli and Colletotrichum gloeosporioides) in chili (Capsicum annuum L.). A flow rate of 10 L/min produced the highest concentration of hydrogen peroxide (H2O2) at 369 mg/L. Results showed that PAW treatment for 30 min and 60 min effectively degrades carbendazim and chlorpyrifos by about 57% and 54% in solution, respectively. In chili, carbendazim and chlorpyrifos were also decreased, to a major extent, by 80% and 65% after PAW treatment for 30 min and 60 min, respectively. E. coli populations were reduced by 1.18 Log CFU/mL and 2.8 Log CFU/g with PAW treatment for 60 min in suspension and chili, respectively. Moreover, 100% of inhibition of fungal spore germination was achieved with PAW treatment. Additionally, PAW treatment demonstrated significantly higher efficiency (p < 0.05) in controlling Anthracnose in chili by about 83% compared to other treatments.

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.

Applying Cold Atmospheric Plasma to Preserve the Postharvest Qualities of Winter Jujube (Ziziphus jujuba Mill. cv. Dongzao) During Cold Storage

Winter jujube (Ziziphus jujuba Mill. cv. Dongzao) is a very popular horticultural fruit worldwide, which contains a high number of bioactive compounds. Nevertheless, jujube is perishable by microbial contamination and has a short shelf life under non-controlled conditions. Cold atmospheric plasma (CAP) presents a great potential for food sterilization, maintain postharvest quality, and prolonged storage time. Herein, this study investigated the potential effect of CAP with different exposure times (0, 5, 10, and 20 min) on the physicochemical and biochemical changes in jujube during 15-day storage at 4°C and 90% relative humidity (RH). The results showed that CAP treatment could obviously delay ripening, but displayed no effects on the speed of weight loss and moisture content. Meanwhile, the total native aerobic bacterial count in each jujube group was restrained during whole storage. However, CAP treatment showed a time-dependent manner to improve gene expression (PAL, 4CL, DFR, ANS, LAR, and ANR) related to phenolic biosynthesis. As compared to other groups, 20-min CAP treatment can keep or increase total phenolic content (TPC), maintain antioxidant activity, and reduce oxidative damage. Furthermore, the hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) content in jujube during middle storage were visibly reduced by 20-min CAP treatment. All in all, our findings concluded that appropriate CAP exposure time can be a promising candidate for the postharvest preservation of jujube.

Ozone in wineries and wine processing: A review of the benefits, application, and perspectives

Ozone (O₃ ) is an emerging eco-friendly technology that has been widely used in the beverage industry due to its broad spectrum of usages, such as fermentation, microbial inactivation, Clean-in-Place (CIP) systems, and postharvest treatment. Wine is among the most financially profitable sectors of the beverage industry. Ozone technology as an alternative approach to conventional methods to inhibit microbes in wine processing and wineries has attracted researchers' attention as this emerging technology will probably play important roles in wineries in the future. This review discusses the prospective applications of ozone in winemaking and wineries and elaborates on ozone's antimicrobial effects on the control of the broad spectrum of microorganisms during wine processing. Also, this paper provides discussions on its effects of O₃  on wine quality and the benefits this emerging technology can bring to wineries. Ozone treatments can improve yeast fermentation by impacting the yeast ecology of postharvested wine grapes, mainly by affecting apiculate yeasts and adjusting the population of undesirable yeasts, such as Brettanomyces spp., during the fermentation process. Furthermore, ozone treatment may enhance wine's anthocyanin concentration, physicochemical properties, color, pH, oxidative stability, and concentration of pleasant volatile compounds and esters. This article presents important information to have a better understanding of the impact of ozone treatment on different stages of wine preparation.

Photolysis for the Removal and Transformation of Pesticide Residues During Food Processing: A State-of-the-Art Minireview

Pesticide residues are of great significant issue that exerted adverse effects on humans. There is a need for effective and non-toxic decontamination of pesticide residues during food processing. In this minireview, the recent advances in the degradation of pesticide residues by photolysis have been firstly described during food processing. The mechanisms of pesticide residues destruction by photolysis were discussed accordingly. Finally, applications of photolysis in the degradation of pesticide residues from beverages, fresh produce, and food rinse waste were also summarized.