Cold Atmospheric Plasma Treatment Research Articles

Effect of cold plasma generated with different gas mixtures on safety, quality and nutritional aspects of fresh sea bream fillets

Cold atmospheric plasma (CAP) is a non-thermal technology, successfully used to decontaminate and extend the shelf-life of various foods. However, since CAP is highly oxidative, it can cause quality deterioration in sensitive matrices, such as fish products. This research aimed to evaluate the effect of CAP treatment with a surface dielectric barrier discharge (SDBD) with different gas mixtures (80% Ar/20% O2, or 80% N2/20% O2) on the decontamination of inoculated pathogens (E.coli and L.innocua; log 4 CFU/g inoculum) and endogenous spoilage microbiota and on the main quality indices of seabream (Spaurus aurata) fillets. For selected appropriate treatments, the impact on the nutritional value of the products was investigated through in vitro digestion, bioaccessibility of fatty acids and the degree of protein hydrolysis.The use of CAP resulted in a decrease in the bacterial load in the fresh sea bream fillets up to 1 log CFU/g obtained with Ar/O2 gas mixture for 20 min, affected by the treatment duration, but not by the gas mixture. Although a slight increase in lipid oxidation was observed (from 0.5 mg MDA/kg to a maximum of 4 mg MDA/kg), the digestibility of the products was not affected. Industrial relevanceFrom an industrial point of view, increasing shelf-life of perishable products such as fish fillets with an environmentally friendly and non-thermal technology could represent a great advantage; however, maintaining quality is of paramount importance for the industrial use of this novel processing technology. The results of the present study show negligible effects on the nutritional quality of seabream fillets, which encourages further research.

Effect of high voltage dielectric barrier discharge (DBD) atmospheric cold plasma treatment on physicochemical and functional properties of taro (Colocasia esculenta) starch

The goal of the proposed study is to investigate the effects of three different power levels (30, 32 and 34 kV) and exposure time (2, 4 and 8 min) of dielectric barrier discharge (DBD) atmospheric cold plasma treatment on the functional and physicochemical characteristics of taro starch. Investigations were done into how different treatments impact the multi-structural, functional and physicochemical attributes of taro starch. The findings showed that cold plasma treatments substantially impacted starch granule shapes (3.60–2.54 μm), such as reduced aggregations and developed fissures on granule surface due to the generation of an etching by plasma species and enhancement in the surface topography and roughness of treated starch as compared with native by SEM and AFM analysis. Besides this, no variations were detected in the functional groups of taro starch using FT-IR analysis after cold plasma treatments. However, the A-type pattern in the XRD did not affect it, while a reduction in relative crystallinity (14.20–11.50 %) was seen as a function of the active plasma species depolymerization. Furthermore, depending on the cold plasma voltage and treatment time, amylose content (20.12–15.98 %), paste clarity (24.48–31.27 %), solubility (0.41–65.53 %), freezing thaw stability (% syneresis) (32.10–42.58 %), color properties (L*, 94.79–97.52), whiteness index (79.37–84.66), molecular weight distribution (Peak 1, 12.79–5.35 × 108 g/mol; Peak 2, 4.20–1.56 × 107 g/mol) and in vitro digestibility (RDS, 64.10–64.08 %) significantly changed. So, based on these excellent properties, this study suggested that cold plasm-treated taro starch can be used in the field of food packaging material, functional food and pharmaceutical products. Therefore, a potential approach for physically altering starch is plasma treatment.

Effect of low current cold atmospheric plasma on grains surface structure and water absorption capacity

The use of preparatory electrophysical methods of influencing food raw materials is one of the main trends in the development of innovative processes and technologies in the food and processing industry. Based on the physical effect of electron emission from a thermal emission source, a cold atmospheric plasma (CAP) was obtained, which was successfully applied to the grain material. Physical characteristics and evolution of low-temperature atmospheric plasma were considered as the main methods of analysis of electrophysical effects. To assess the effect of low-temperature plasma on grain material, measurements of water absorption capacity and analysis of surface modification by electron scanning microscopy were carried out. It has been experimentally established that CAP treatment contributes to a more intensive process of water absorption due to changes in the surface structure of the grain material. The total duration of the process of water absorption of grain material after processing of CAP decreased by more than three times until the equilibrium moisture content was reached. Scanning electron microscopy has shown that the processing of CAP leads to the appearance of a fine-mesh structure of the surface of the grain material. The effect of CAP treatment leads to modification of the seed surface, which consists in the manifestation of a fine-meshed structure on the surface of the seeds. Taking into account the advantages of CAP technology, namely the absence of the need for vacuuming and short processing time, the technology has a high practical potential.

Recent strategies for improving the quality of meat products.

Processed meat products play a vital role in our daily dietary intake due to their rich protein content and the inherent convenience they offer. However, they often contain synthetic additives and ingredients that may pose health risks when taken excessively. This review explores strategies to improve meat product quality, focusing on three key approaches: substituting synthetic additives, reducing the ingredients potentially harmful when overconsumed like salt and animal fat, and boosting nutritional value. To replace synthetic additives, natural sources like celery and beet powders, as well as atmospheric cold plasma treatment, have been considered. However, for phosphates, the use of organic alternatives is limited due to the low phosphate content in natural substances. Thus, dietary fiber has been used to replicate phosphate functions by enhancing water retention and emulsion stability in meat products. Reducing the excessive salt and animal fat has garnered attention. Plant polysaccharides interact with water, fat, and proteins, improving gel formation and water retention, and enabling the development of low-salt and low-fat products. Replacing saturated fats with vegetable oils is also an option, but it requires techniques like Pickering emulsion or encapsulation to maintain product quality. These strategies aim to reduce or replace synthetic additives and ingredients that can potentially harm health. Dietary fiber offers numerous health benefits, including gut health improvement, calorie reduction, and blood glucose and lipid level regulation. Natural plant extracts not only enhance oxidative stability but also reduce potential carcinogens as antioxidants. Controlling protein and lipid bioavailability is also considered, especially for specific consumer groups like infants, the elderly, and individuals engaged in physical training with dietary management. Future research should explore the full potential of dietary fiber, encompassing synthetic additive substitution, salt and animal fat reduction, and nutritional enhancement. Additionally, optimal sources and dosages of polysaccharides should be determined, considering their distinct properties in interactions with water, proteins, and fats. This holistic approach holds promise for improving meat product quality with minimal processing.

Inactivation of Alicyclobacillus acidoterrestris vegetative cells and spores induced by atmospheric cold plasma

This study aimed to inactivate Alicyclobacillus acidoterrestris vegetative cells and spores (107–108 CFU/mL) using atmospheric cold plasma (ACP). Alicyclobacillus acidoterrestris vegetative cells decreased by 6.63 and 6.47 log under only ACP treatment of 30 kV for 6 min in saline solution and apple juice, respectively. ACP was less effective against spores, resulting in 2.64 and 2.43 log reductions at the same treatment parameter. However, better inactivation (4.03 log and 3.95 log) was achieved in apple juice and saline solution using ACP at 30 kV combined with mild heat (85 °C) for 6 min. Morphological observation and intracellular substance release revealed severe structural damage to spores induced by ACP. The application of ACP resulted in improved color, reduced pH, and increased levels of total phenolic content and total soluble solids in apple juice. This study offers an effective method for inactivating Alicyclobacillus acidoterrestris in apple juice. Industrial relevanceThe application of atmospheric cold plasma in combination with mild heat to effectively inactivate Alicyclobacillus acidoterrestris in apple juice offers a promising method for ensuring juice product quality. The enhancement of color, reduction in pH, and increase in total phenolic content and total soluble solids further underscore the potential benefits of this technique for enhancing the sensory attributes of apple juice. This study offers a potential approach that may directly contribute to enhancing production practices and product value.

Cold Atmospheric Pressure Plasma Jet and Plasma Lamp Interaction with Plants: Electrostimulation, Reactive Oxygen and Nitrogen Species, and Side Effects

Cold atmospheric pressure plasma (CAPP) treatment is a highly effective method of protecting seeds, plants, flowers, and trees from diseases and infection and significantly increasing crop yields. Here we found that cold atmospheric pressure He-plasma jet (CAPPJ) can also cause side effects and damage to plants if the plasma exposure time is too long. Reactive oxygen and nitrogen species (RONS), electromagnetic fields, and ultraviolet photons emitted by CAPPJ can cause both positive and negative effects on plants. CAPPJ can interact with biological tissue surfaces. The plasma lamp has no visible side effects on Aloe vera plants, cabbage, and tomatoes. A plasma lamp and a cold atmospheric pressure plasma He-jet cause strong electrical signaling in plants with a very high amplitude with frequencies equal to the frequency of plasma generation. The use of plasma lamps for electrostimulation of biological tissues can help to avoid side processes in biological tissues associated with the generation of RONS, UV photons, and direct interaction with cold plasma. CAPP technology can play an important role in agriculture, medicine, the food industry, chemistry, surface science, material science, and engineering applications without side effects if the plasma exposure is short enough.

Cold Plasma Technology for Tomato Processing By-Product Valorization: The Case of Tomato Peeling and Peel Drying

The tomato processing industry is focused on product yield maximization, keeping energy costs and waste effluents to a minimum while maintaining high product quality. In our study, cold atmospheric plasma (CAP) pretreatment enhanced tomato processing to facilitate peelability, a specific peeling process, and enhance peel drying. Peeling force analysis determined that CAP pretreatment of whole tomatoes improved peelability under the conditions used. The specific peeling force after CAP treatment decreased by more than three times. It was observed that cold atmospheric plasma pretreatment reduced the duration of infrared drying of tomato peels by 18.2%. Along with that, a positive effect on the reduction of the specific energy consumption of peel drying was shown for CAP-pretreated tomato peels. The obtained data show that the technology of cold atmospheric plasma pretreatment, in particular, when processing whole tomatoes and tomato peels, has a promising application in industry, as it can significantly reduce the specific energy consumption for peeling and drying procedures.

Dielectric Barrier Discharge Cold Atmospheric Plasma Treatment of Egg White Protein: Insights into the Functional, Rheological, and Structural Properties

Dielectric Barrier Discharge Cold Atmospheric Plasma Treatment of Egg White Protein: Insights into the Functional, Rheological, and Structural Properties

Cold atmospheric pressure plasma: A potential physical therapy for rheumatoid arthritis hyperplastic synovium

The most significant pathological change in rheumatoid arthritis (RA) is synovial hyperplasia within the joint. The production of a series of degrading enzymes and oxidative stress caused by synovial hyperplasia lead to severe bone and cartilage damage in rheumatoid joints. The core effector cell in hyperplastic synovium is fibroblast-like synovium cells, which can invade cartilage, cause inflammation, destroy joints, and show tumor-like anti-apoptosis characteristics. This study focused on the effect of cold atmospheric pressure plasma on proliferative synovium, and the results showed that no synovial hyperplasia, angiogenesis, or inflammatory infiltration was observed after cold atmospheric pressure plasma (CAP) treatment. The molecular and cellular mechanisms also reveal the spontaneous reactive oxygen species (ROS) cascade inducing apoptosis in rheumatoid arthritis fibroblast-like synoviocytes (RA-FLS) cells. This study proposes a potential physical therapy method for treating proliferative synovium and also provides ideas for the application of CAP in other types of tumor diseases.

Coconut milk treated by atmospheric cold plasma: Effect on quality and stability

Commercial sterilization plays an important role in extending the shelf-life of coconut milk. However, thermal sterilization affects the quality of coconut milk. This study was initiated to evaluate the effects of atmospheric cold plasma (ACP) treatment on some important quality parameters of coconut milk. ACP treatment had a slight effect on physicochemical characteristics and nutritional ingredients while it obviously reduced the colony count. Furthermore, ACP treatment obviously promoted the formation of lactone, an indispensable volatile substance in coconut milk. Insufficient or moderate ACP treatment had subtle effect on the sensory quality. Notably, moderate ACP treatment reduced the droplet size from 28.0 μm to 18.6 μm, and improved the stability during storage and centrifugation, especially at 60 kV 60 s. Overall, sterilization of coconut milk by ACP at 60 kV 60 s was the most ideal. This study can provide theoretical guidance for the application of ACP in liquid food.

A Prospective Randomized Controlled Pilot Study to Assess the Response and Tolerability of Cold Atmospheric Plasma for Rosacea

Introduction: Rosacea is a common, facial, chronic inflammatory skin disease. Due to its complex pathogenesis, adequate therapy of rosacea can be challenging. An innovative recent therapeutic tool is cold atmospheric plasma (CAP), which is already established in the treatment of chronic wounds and promising in different other skin diseases. Methods: In a split-face pilot study we investigated dielectric-barrier-discharged CAP in erythemato-telangiectatic (ETR) and/or papulopustular rosacea (PPR). CAP treatment was applied on lesional skin of a randomized side once daily (90 s/area) for 6 weeks. The other untreated side served as control. Co-primary endpoints were ≥1 improvement of the Investigator Global Assessment (IGA) score on the treated side compared to control and a decline of the Dermatology Life Quality Index (DLQI) after 6 weeks. Secondary endpoints included inflammatory lesion count (papules and pustules), skin redness intensity and erythema size. Adverse events (AEs) were recorded constantly. Additionally, participants were weekly assessed for symptoms, skin condition, trigger factors, skin care, treatment success, and local tolerance parameters. All p values were calculated using the Wilcoxon signed-rank test. Results: Twelve subjects (ETR, n = 3; ETR and PPR, n = 9) completed the study. DLQI was significantly improved after 6 weeks (p = 0.007). On the CAP-treated side, lesions (p = 0.007) and erythema size (p = 0.041) were significantly reduced compared to the control. IGA (p = 0.2) and skin redness intensity (p = 0.5) did not differ significantly between control and CAP-treated side. No serious AEs occurred and treatment was well tolerated. Conclusion: CAP is a promising new treatment of rosacea, especially for PPR.

Application of cold atmospheric plasma for mold inactivation

Mold growth in indoor interiors is an increasing problem that has adverse effects on both occupants and building materials. The aim of this study was to present the new environmentally friendly method (cold atmospheric plasma treatment) for decontamination of indoor environments contaminated by mold spores, with the potential to become an effective replacement for conventional methods, such as ultraviolet-C (UV-C) germicidal irradiation. The spores of Aspergillus species on malt extract agar plates were exposed to plasma produced by diffuse coplanar surface barrier discharge. The surface coverage of mold was evaluated using image analysis. Cold plasma treatment inactivated spores on the surface of the culture medium in 0.5 min, whereas a weak growth delay was observed after 30 minute exposure to UV-C irradiation. This study demonstrated that cold atmospheric plasma is a more effective method for reducing mold spores on agar compared with germicidal UV-C irradiation.

Modification of Silicon Nanostructures by Cold Atmospheric Pressure Plasma Jets

Cold atmospheric plasma (CAP) jets with helium (He) and argon (Ar) plasma-forming gases were used to modify the structure, photoluminescence (PL), and electrical properties of arrays of silicon nanowires (SiNWs) with initial cross-section sizes of the order of 100 nm and length of about 7‒8 microns. The CAP source consisted of a 30 kHz voltage generator with a full power up to 5 W and the CAP treatment for 1‒5 min resulted in spattering of SiNWs’ tips followed by redeposition of silicon atoms. An increase of the silicon oxide phase and a decrease of the PL intensity were observed in the plasma processed SiNW arrays. A decrease of the free hole concentration and an increase in the free electron density were revealed in heavily boron and phosphorous doped SiNWs, respectively, as it was monitored by means of the Raman spectroscopy, considering a coupling of the light scattering by phonon and free charge carriers (Fano effect) in SiNWs. The obtained results demonstrate that the CAP treatment can be used to change the length, sharpness, luminescence intensity, and electrical properties of silicon nanowires for possible applications in optoelectronics and sensorics.

Decontaminative Properties of Cold Atmospheric Plasma Treatment on Collagen Membranes Used for Guided Bone Regeneration.

Background cold atmospheric plasma (CAP) is known to be a surface-friendly yet antimicrobial and activating process for surfaces such as titanium. The aim of the present study was to describe the decontaminating effects of CAP on contaminated collagen membranes and their influence on the properties of this biomaterial in vitro. Material and Methods: A total of n = 18 Bio-Gide® (Geistlich Biomaterials, Baden-Baden, Germany) membranes were examined. The intervention group was divided as follows: n = 6 membranes were treated for one minute, and n = 6 membranes were treated for five minutes with CAP using kINPen® MED (neoplas tools GmbH, Greifswald, Germany) with an output of 5 W, respectively. A non-CAP-treated group (n = 6) served as the control. The topographic alterations were evaluated via X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). Afterward, the samples were contaminated with E. faecalis for 6 days, and colony-forming unit (CFU) counts and additional SEM analyses were performed. The CFUs increased with CAP treatment time in our analyses, but SEM showed that the surface of the membranes was essentially free from bacteria. However, the deeper layers showed remaining microbial conglomerates. Furthermore, we showed, via XPS analysis, that increasing the CAP time significantly enhances the carbon (carbonyl group) concentration, which also correlates negatively with the decontaminating effects of CAP. Conclusions: Reactive carbonyl groups offer a potential mechanism for inhibiting the growth of E. faecalis on collagen membranes after cold atmospheric plasma treatment.

Reaction mechanism for atmospheric pressure plasma treatment of cysteine in solution

Mechanisms for the cold atmospheric plasma (CAP) treatment of cells in solution are needed for more optimum design of plasma devices for wound healing, cancer treatment, and bacterial inactivation. However, the complexity of organic molecules on cell membranes makes understanding mechanisms that result in modifications (i.e. oxidation) of such compounds difficult. As a surrogate to these systems, a reaction mechanism for the oxidation of cysteine in CAP activated water was developed and implemented in a 0-dimensional (plug-flow) global plasma chemistry model with the capability of addressing plasma-liquid interactions. Reaction rate coefficients for organic reactions in water were estimated based on available data in the literature or by analogy to gas-phase reactions. The mechanism was validated by comparison to experimental mass-spectrometry data for COST-jets sustained in He/O2, He/H2O and He/N2/O2 mixtures treating cysteine in water. Results from the model were used to determine the consequences of changing COST-jet operating parameters, such as distance from the substrate and inlet gas composition, on cysteine oxidation product formation. Results indicate that operating parameters can be adjusted to select for desired cysteine oxidation products, including nitrosylated products.

Effect of direct plasma treatment and plasma‐treated liquid on cutaneous squamous cell carcinoma: A proof‐of‐concept study

AbstractThis study investigates the efficacy of cold atmospheric plasma (CAP) in treating squamous cell carcinoma (SCC), a highly metastatic cancer. To assess the anticancer activity, two CAP treatment methods—direct treatment and indirect treatment (plasma‐treated N‐acetyl cysteine solution)—were used. Results indicate that both methods selectively target SCC cells, inducing oxidative and nitrosative stress, leading to decreased metabolic activity and increased apoptosis. Furthermore, a critical feature of cancer cells, metastatic behavior is also inhibited by CAP treatment. Coculture experiments demonstrate the effectiveness of CAP treatment in selectively inactivating SCC cells while leaving healthy cells unaffected. These findings suggest the potential use of CAP as a selective and effective treatment for SCC.

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

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

Assessment of Cold Atmospheric Pressure Plasma (CAPP) Treatment for Degradation of Antibiotic Residues in Water.

The presence of antibiotic residues in water is linked to the emergence of antibiotic resistance globally and necessitates novel decontamination strategies to minimize antibiotic residue exposure in both the environment and food. A holistic assessment of cold atmospheric pressure plasma technology (CAPP) for β-lactam antibiotic residue removal is described in this study. CAPP operating parameters including plasma jet voltage, gas composition and treatment time were optimized, with highest β-lactam degradation efficiencies obtained for a helium jet operated at 6 kV. Main by-products detected indicate pH-driven peroxidation as a main mechanism of CAPP-induced decomposition of β-lactams. No in vitro hepatocytotoxicity was observed in HepG2 cells following exposure to treated samples, and E. coli exposed to CAPP-degraded β-lactams did not exhibit resistance development. In surface water, over 50% decrease in antibiotic levels was achieved after only 5 min of treatment. However, high dependence of treatment efficiency on residue concentration, pH and presence of polar macromolecules was observed.

Effect of cold atmospheric plasma induced electric field on aquaporin-5 structure and ROS transport

Cold atmospheric plasma (CAP) treatment has been believed to be a promising anticancer technology. Aquaporins (AQPs) are inferred as a main but unverified route of ROSs transport into cancer cells. Molecular dynamics simulations were carried out to assess the effect of CAP-induced electric field on the AQP5-biolayer combination, the AQP5 structure, and the ROS distribution. Results show that the electric field can weaken the AQP5-biolayer combination, and narrow the radius of AQP5 water pores by changing the distance of key residues. From the perspective of ROS, the electric field sharply changes the free energy profiles of polarized ROSs but hardly affects the distribution of hydrophilic ROSs. This work provides a microscopic perspective of the CAP anticancer mechanism and puts forward the electric field as a new factor in CAP-related research.

How living cells are affected during the cold atmospheric pressure plasma treatment

When the electric discharge process is limited by high voltage electrodes shielding, the ionization measure would be controlled to less than one percent and the temperature to less than 37 °C even at atmospheric pressure, so-called cold atmospheric pressure plasma (CAP). CAP has been found to have profound medical applications in association with its reactive oxygen and nitrogen species (ROS/RNS). In this way that during plasma exposure, the subjected medium (e.g. cell cytoplasmic membrane in plasma therapy) interacts with ROS/RNS. Accordingly, a precise study of the mentioned interactions and their consequences on the cells' behavior changes, is necessary. The results lead to the reduction of possible risks and provide the opportunity of optimizing the efficacy of CAP before the development of CAP applications in the field of plasma medicine. In this report molecular dynamic (MD) simulation is used to investigate the mentioned interactions and a proper and compatible comparison with the experimental results is presented. Based on this, the effects of H2O2, NO and O2 on the living cell's membrane are investigated in biological conditions. Our results show that: i) The hydration of phospholipid polar heads would be enhanced associated with the H2O2 presence. ii) A new definition of the surface area assigned to each phospholipid (APL), more reliable and compatible with the physical expectations, is introduced. iii) The long-term behavior of NO and O2 is their penetration into the lipid bilayer and sometimes passing through the membrane into the cell. The latter would be an indication of internal cells' pathways activation leading to modification of cells' function.