Cold Plasma Treatment Research Articles

Effect of atmospheric cold plasma treatment modes on the quality of red shrimp (Solenocera crassicornis) during cold chain storage

An increasingly popular non-thermal approach for food preservation is atmospheric cold plasma (ACP), which can efficiently inactivate various microorganisms. This study explored the impact of different ACP treatment modes on the preservation of red shrimp in cold chain storage. A novel treatment mode, ACP cyclical, was introduced as an alternative to ACP one-time treatment. The results indicated that the ACP cyclical treatment extended the ozone and shrimp exposure time to 35 min compared to one-time treatment, resulting in a notable enhancement in preservation effectiveness. While ACP treatment significantly reduced the total viable count (TVC) of red shrimp at day 0, it does not affect total volatile basic-nitrogen (TVB-N), pH value, or color. At day 8, the ACP cyclical group showed a 17.38% reduction in TVB-N, 36.90% decrease in TVC, and 32.39% decline in sulfur-producing bacteria compared to the ACP one-time treatment group. Electronic nose analysis indicated improved odor stability in both ACP treatment modes. Moreover, correlation and partial least squares discriminant analysis revealed that ACP cyclical treatment delayed shrimp’ color deterioration and TVB-N increase during prolonged storage. This study highlighted the potential of ACP cyclical treatment for enhancing red shrimp preservation in cold chain storage.

Effect of oxygen plasma-treatment on surface functional groups, wettability, and nanotopography features of medically relevant polymers with various crystallinities

The surface properties of polymeric biomaterials play a crucial role in their biocompatibility and performance. This study explores the application of cold oxygen plasma treatment as a versatile technique for surface modification of polymeric materials with different degrees of crystallinity: crystalline high-density polyethylene (HDPE), crystalline-amorphous poly(chloro‑paraxylylene) (parylene C), and amorphous aromatic polyether-based polyurethane (PU). The investigations focus on the generation of surface functional groups and hydrophilicity, as well as nanotopography. X-ray photoelectron spectroscopy (XPS) analysis confirmed the generation of oxygen-containing functional groups, resulting in controlled wettability (water contact angle), while atomic force microscopy (AFM) showed topography modifications in the nanoscale. At the same time, it was revealed that oxygen plasma treatment did not affect the bulk properties (confirmed by TG and XRD). The effects of the same plasma treatment conditions varied significantly among the different polymers studied, depending on their crystallinity. This was discussed in terms of the preferential etching of amorphous regions in the polymeric structures. The findings emphasize the advantages of oxygen plasma treatment for tailoring the surface properties of polymeric biomaterials, highlighting its significance for biomedical applications.

Synergistic effect of CaCO3 addition and cold atmospheric plasma treatment on the surface evolution, mechanical properties, and in-vitro degradation behavior of FDM-printed PLA scaffolds

The ease of processing and biocompatibility of polylactic acid (PLA) have made it a widely used material for fused deposition modeling (FDM)-based 3D printing. In spite of this, PLA suffers from some limitations for its extensive use in tissue engineering applications, including poor wettability, low degradation rate, and insufficient mechanical properties. To address the previously mentioned limitations, this study examined how combining in-process cold atmospheric plasma treatment with the inclusion of CaCO3 influences the properties of FDM-printed PLA scaffolds. Differential scanning calorimetry results showed that by incorporating CaCO3 micro-particles into the PLA matrix, heterogeneous nucleation promoted the matrix's crystalline content. Scanning electron microscopy analysis revealed that the surface of the PLA-CaCO3 scaffold exhibited increased roughness and improved interlayer bonding after undergoing plasma treatment. Atomic force microscopy revealed a significant (up to 80-fold) increase in the roughness value of PLA scaffolds after the incorporation of CaCO3 and subsequent cold plasma treatment. Furthermore, X-ray photoelectron spectroscopy analysis indicated that atmospheric plasma treatment substantially increased the presence of oxygen-containing bonds, leading to a significant reduction in the water contact angle, which decreased from 89° to 37°. According to the tensile test, the tensile modulus (634.1 MPa) and ultimate tensile strength (25.4 MPa) of PLA were markedly increased and reached 914.3 and 37.2 MPa, respectively, for the plasma-treated PLA-CaCO3 (PT-PLA-CaCO3). Additionally, the in-vitro degradation test showed that PT-PLA-CaCO3 scaffold exhibited higher degradation rate compared to the PLA-CaCO3 sample. Based on the obtained results, it appears that in-process cold atmospheric plasma treatment could serve as an efficient and straightforward method to enhance the properties of 3D-printed composite parts, particularly for tissue engineering applications.

Conjugation of dual-natural milk-derived proteins with fucoidan to prepare controllable glycosylation products via dielectric barrier discharge cold plasma

This study reported that fibrillar bridges (whey protein isolate nanofibrils, WPNs) were used to associate the casein (CA) nanoparticles through the pH-driven method to obtain the self-assembled WPN-CA complexes. Then, a novel technology involving cold plasma (CP) was innovatively proposed to enhance the protective properties of complexes. The confirmation of structural transitions and interactions resulting from the adjustment of WPN-to-CA ratios (WtCs) led to the identification of the complexes named WPCA (WtC1.0:1). Next, the results showed a rapid conjugation between WPCA and fucoidan (FD) with a degree of grafting of 16.03 % after 10 min CP treatment. The coupling of WPCA with FD to form conjugates was confirmed by SDS-PAGE analysis, indicating covalent bonds' formation. FTIR spectroscopy revealed an augmentation in the intensity of the OH stretching vibration of the WPCA-FD conjugate, concomitant with a decrease in β-turns and an elevation in β-sheets content. Furthermore, the application of glycosylation treatment to WPCA-FD resulted in a noteworthy enhancement of both the thermal stability and antioxidant activity characteristics of WPCA. Our findings move a step forward, as CP-assisted Maillard reaction has shown potential as an efficient and energy-saving method to enhance the functional properties of milk-derived proteins in the food industry.

Germination improvement of fenugreek seeds with cold plasma: Exploring long-lasting effects of surface modification

Pre-sowing cold plasma (CP) treatment of seeds is a proven method for enhancing seed germination and plant growth. This paper presents a study on the long-lasting effects of CP treatment on fenugreek (Trigonella foenum-graecum) seeds to elucidate the basic mechanism of plasma action and pave the way for future field experiments. The seeds were subjected to short-duration treatments (10 and 20 s) using the kINPen 11 plasma jet and then stored for 3 months before sowing. After this period, the treated seeds exhibited higher germination efficiency, and the resulting seedlings were longer and more vigorous compared to normal seedlings. The improvement in germination was particularly noticeable for a treatment time of 20 s. Although we observed the age-related hydrophobic recovery, the plasma-treated seeds consistently showed better wettability than the control group. However, no direct correlation was found between wettability and germination improvement. Scanning electron microscopy (SEM) analysis revealed increased surface roughness and microstructuring of the outer layers of the seed coat after plasma treatment, while X-ray photoelectron spectroscopy (XPS) indicated an increase in the O/C ratio, as well as the presence of calcium and potassium. These findings suggest that the argon plasma etched the uppermost layer of the seed coat, leading to structural changes. It is suspected that the observed faster germination and growth of plasma-treated seeds is seeds due to these long-lasting changes in the seed coat structure, which may disrupt its tissues and open access to the interior of the seed. Under appropriate conditions, this facilitates an increase in the metabolic activity of the embryo. Such a mechanism can be considered as plasma scarification of the seed. This study highlights the potential of cold plasma technology as a viable and simple strategy for improving seed germination and plant growth in the long term, with important implications for the agricultural sector.

Understanding the Electrooxidation of Dimethyl Ether on Pt3Pd3Sn2 Supported on a Mixture of Carbon Materials

Recently, we reported a rigorous study on the effect of carbon supports and their cold plasma treatment on a state-of-the-art catalyst, Pt3Pd3Sn2, for dimethyl ether (DME) electrooxidation. The catalyst supported on a mixture of 75% activated multi-walled carbon nanotube (MWCNT) (75 M) and 25% pristine black pearl 2000 (BP2000) (25B) (Pt3Pd3Sn2/75M25B) offered improved DME kinetics with respect to the single or other combinations of the same supports. In this work, the results of the electrochemical impedance spectroscopy (EIS) were coupled with physicochemical characterizations (X-ray Diffraction (XRD), Small Angle X-ray Scattering (SAXS), and Scanning Tunneling Electron Microscopy (STEM)) for a detailed understanding of the origins of the improved kinetics. With an appropriate composition of the two supports in the mixture (75M25B), a catalyst with optimized particle size, dispersion, and conductivity was obtained. A Pt3Pd3Sn2/75M25B-coated electrode exhibited a reduced charge transfer resistance of 0.63 ohms at the catalyst layer compared to BP2000 and MWCNT, which showed 1.53 and 1.31 ohms, respectively. These results provide vital insights into catalyst support design considering the use of support mixtures of optimized conductivity and surface area for enhanced power output.

Potential biomarkers analysis and protein internal mechanisms by cold plasma treatment: Is proteomics effective to elucidate protein-protein interaction network and biochemical pathway?

New market trends of meat flavor, tenderness, and color quality indicators have prompted the research on meat preservation as a crucial topic to received attention. Present research about the effects of irradiation, cold plasma technology on meat is incomplete. There are strongly recommended that proteomics techniques be jointly to enhance the coverage of internal meat molecules for meat research. By identifying meat proteins, detecting biological functions, and quantifying the protein segments of specific meat biomarkers, which can be provided for the information of diagnostic components in preservative technologies. The current review provides scientific findings on various control strategies: (i) combine the data-independent acquisition to provide a reference for the meat molecular mechanism and rapid identification; (ii) design molecular networks biological functions assessment model; (iii) molecular investigations of cold plasma techniques and underlying mechanisms; (iv) explore the X-rays and γ-rays treatment in meat preservation and myoglobin change mechanism more comprehensively.

Deciphering morphological and biochemical responses of Salvia leriifolia to seed cold plasma treatment, priming, and foliar spraying with nano-salicylic acid

The pretreatment of seeds with cold plasma (CP) (0 and 100 w for 240 s), and salicylic acid priming (SA) (0 and 2 mM normal and nano form), and foliar spraying of SA at the six-leaf stage (0 and 2 mM normal and nano form) of Salvia leriifolia plants in field condition was studied. Compared to the control plants of S. leriifolia, the results showed that CP + both forms of SA priming + nano-SA spraying increased plant height, leaf length, plant dry weight, total phenol, and the activities of phenylalanine ammonia-lyase (PAL) and tyrosine ammonia-lyase (TAL) enzymes. The chlorophyll a and b contents in all treated plants remained either unchanged or decreased when compared to the control. The highest PAL activity was obtained in CP-free + hydro-priming + nano-SA foliar spraying. The highest content of caffeic acid was achieved in CP + SA priming + SA foliar spraying in the leaf. The maximum contents of rosmarinic and salvianolic acid were obtained in the control plants. In conclusion, CP and nano-SA can increase PAL and TAL activity and total phenol accumulation in S. leriifolia plants, but not rosmarinic and salvianolic acid contents. Other phenolic compound enzymes and their production require further study.

Microwave and atmospheric cold plasma aided debittering of giloy (Tinospora cordifolia Miers.) juice: Effect on bioactive compound content

Giloy (Tinospora cordifolia Miers.) is a well-known herbal medicinal plant that is therapeutically rich in secondary metabolites but is bitter in taste, thereby limiting its potential to be used as a functional food. Hence, this study was aimed at reducing the bitterness of giloy juice through cold plasma (CP) (10–30 kV, 10–40 min, CCD with 5 center points) and microwave (MW) (100–180 W, 5–15 min) applications, making it available in a more palatable form, which is quite a noble approach unlike already existing debittering methods like ultrasound and β-cyclodextrin incorporation methods. Bicyclic diterpenoids are the principal bitterness-causing element in giloy; hence, total terpenoid content (TTC) was taken as the gauging factor to scale the bitterness while targeting higher concentrations of various bioactive compounds (BCs) through FRAP, TPC, TFC, and DPPH radical scavenging activity assays. RSM is used to address the change in BCs’ content with respect to the influencing factors. A decrease in TTC in giloy juice was observed by 73% after a CP treatment of 30 kV for 25 min and by 26.5% in a MW treatment of 100 W for 15, which the FTIR results also corroborate. The physical surface morphology of the sample was found to be affected by the CP and MW treatments, as evidenced by the SEM images, which aided in the evaporation and diffusion of BCs and further variations in their functionality owing to the operating conditions. CP though was effective in reducing the TTC but MW was good at extracting terpenoids along with other BCs.

Effects of combined chlorogenic acid and cold plasma on the colour and flavour of roasted mutton patties

SummaryPolyphenol addition and cold plasma (CP) treatment are both potential technologies in the meat industry. In this study, six treatments, control (without chlorogenic acid and plasma treatment), CA (with only chlorogenic acid addition), CA‐CP‐15, CA‐CP‐30, CA‐CP‐45 and CA‐CP‐60 (cold plasma treated chlorogenic acid solution for 15, 30, 45 and 60 min), were used to investigate the effect of cold plasma treated chlorogenic acid solution on the quality of roasted mutton. The results showed that the redness (a*) of CA‐CP‐15 was increased by 40.7% compared to the control group. The synergistic treatment promoted the unfolding of α‐helix and formation of β‐fold in the roasted meat proteins, resulting in a 34.09% decrease in the shear force value of CA‐CP‐15 and differences in muscle fibre structure among the treatment groups. The significantly enhanced free radical scavenging capacity resulted in a 39.19–64.84% inhibition of lipid oxidation. Furthermore, the odour activity values indicated that thirteen volatile components such as 1‐Octen‐3‐ol, Hexanal, 2‐ethyl‐3,5‐dimethyl‐pyrazine and 2‐pentyl‐Furan could be considered as characteristic flavour compounds of roasted mutton. In conclusion, cold plasma treatment improved the quality of roasted mutton patties. This study provides a new idea for the application of cold plasma in meat processing.

Enhancing microorganism inactivation performance through optimization of plate-to-plate dielectric barrier discharge cold plasma reactors

Atmospheric pressure dielectric barrier discharge cold plasma (CP) is an effective method for inactivating microorganism contamination. However, improving CP inactivation efficiency as affected by CP reactor parameters still remains unstudied. In this study, the effects of discharge voltage, dielectric material and dielectric thickness of CP reactor on inactivation performance were investigated, and their influence mechanisms on plasma discharge were discussed. Results indicated that efficiency was improved using the reactor parameters of a high discharge voltage (17 kV) with a centre frequency (10 kHz) and a high dielectric constant (ceramic) with a small dielectric thickness (1 mm), resulting in higher electron number density and electric field strength, producing more reactive substances for enhancing microorganism inactivation. Under the above conditions, CP treatment for 4 min inactivated 99.6% of Salmonella typhimurium and 96.1% of Listeria monocytogenes. It is hoped that this work could guide the design of commercial CP systems.

Coating of Polypropylene Non‐Woven Fabric with Layered Double Hydroxides Bearing Antioxidant and Antibacterial Natural Compounds

AbstractLayered double hydroxides (LDHs) containing immobilized rosmarinic acid or eugenol have been employed to functionalize polypropylene (PP) non‐woven fabric (NWF), commonly used to manufacture protective clothing such as surgical masks. Rosmarinic acid and eugenol have recognized biological activities, such as antimicrobial, antioxidant, and anti‐inflammatory capabilities, and they have been employed in this work both as synthetic, commercial compounds and as raw mixtures extracted from agri‐food matrices. These encapsulated hybrid systems have been designed to gradually release the active molecules while protecting them from degradation processes caused by light and heat. Two different NWF modification strategies have been employed to increase the adhesion capacity of the hybrids: cold plasma treatment with oxygen and polydopamine coating. Both methodologies have increased the amount of hybrid deposited on the NWF surfaces, giving significant resistance to thermo‐oxidation, the controlled migratory capacity of active molecules, and, in the case of the eugenol‐containing system, significant bactericidal activity against Staphylococcus aureus.

Changes in the structure and hydration properties of high-temperature peanut protein induced by cold plasma oxidation

To improve the hydration properties of high-temperature pressed peanut protein isolate (HPPI), we investigated the effect of cold plasma (CP) oxidation on functional and structural properties. Compared to HPPI, the hydrated molecules number and the surface contact angle were significantly decreased at 70 W, from 77.2 × 109 to 17.7 × 109 and from 85.74° to 57.81°, respectively. The reduction of the sulfhydryl content and the increase of the disulfide bond and di-tyrosine content indicated that the structural transformation was affected by the oxidation effect. In terms of structural changes, a stretched tertiary structure, ordered secondary structure, and rough apparent structure were observed after CP treatment. Additionally, the enhancement of surface free energy and group content such as -COOH, -CO and -OH on the surface of HPPI contributed to the formation of hydrated crystal structures. In general, the oxidation effect of CP effectively improved the hydration properties of HPPI and broaden its application field.

Radiofrequency cold plasma – A novel tool for flavour modification in fresh and freeze-dried strawberries

Cold plasma treatment is an emerging non-thermal food processing tool. This study aimed to identify how cold plasma can improve the aroma of a model space food system (freeze-dried strawberries) by mitigating freeze-drying aroma losses. Cold plasma significantly reduced the negative impact of freeze-drying on aroma; hence, it might be useful as a secondary treatment technique for foods that require extended shelf-life with improved aroma, such as in space travel. “Zero-averaged gravity” (0.004 g), a proxy for non-terrestrial environments, reduced the abundance of two important volatile aroma compounds (methyl butanoate and methyl hexanoate) in the gas phase above strawberries; this loss was mitigated when treated by cold plasma. The impact of cold plasma on aroma was also shown to be matrix and treatment parameter-dependent, and six cold plasma treatment options were subsequently identified as enabling bespoke aroma modifications that ultimately enhanced strawberry aroma compounds.

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.

Impact of non-thermal plasma on betel leaf powder for essential oil extraction and its quality characteristics.

Betel leaf is an essential oil (EO)-rich plant from the Piperaceace family used as traditional herbal medicine. The minimum EO yield by the conventional extraction method was increased by adopting cold plasma (CP) as pretreatment. Thus, the present study involved optimizing the CP conditions and analyzing the EO's qualities. Optimization of the CP parameters like electric voltage (A = 25-35 kV), treatment duration (B = 4-12 min) and extraction time (C = 60-180 min) was done for maximum EO yield (R1) and total phenolic content (TPC; R2) using response surface methodology with Box-Behnken design. Maximum EO yield (20.76 ± 1.15 g kg-1 ) and TPC (29.43 ± 1.7 mg GAE mL-1 ) were derived under optimal conditions: A = 34 kV, B = 10 min and C = 110 min. A quadratic polynomial model developed by multiple regression analysis revealed that the three independent variables significantly influenced the oil yield and TPC with R2 values of 0.9909 and 0.9962, respectively. The CP treatment significantly altered the betel leaf powder morphology and increased the EO's radical scavenging capacity and bioactive compounds like chavibetol, chavibetol acetate, hydroxychavicol and γ-muurolene. Conversely, the functional groups, refractive index and specific gravity were unaffected by CP treatment. The EO yield and its qualities were improved by applying CP under optimal conditions which can be helpful for scaled-up industrial processes with further studies. The identified bioactive compounds are valuable in the food and pharmaceutical industries. © 2023 Society of Chemical Industry.

Effect of post-harvest cold plasma treatment on physicochemical properties and inactivation of Penicillium digitatum in Persian lime fruit

Cold atmospheric plasma (CAP) treatment is used in this study to inactivate Penicillium digitatum in lime fruit at post-harvest. Limes were inoculated manually withP. digitatum spore (106 CFU/fruit) and then were treated with CAP at 30, 60, 90, and 120 s and compared with untreated samples. The results showed that increasing the exposure time of CAP reduced spores to less than 7 CFU/fruit in 120 s on the lime peel. In the treated samples, antioxidant activity had an upward trend. In addition, phenolic compounds, vitamin C, density, soluble solid content (SSC), color, and pH of the lime juice were increased (P < 0.05). Compared to the control sample, no significant changes were observed in the juice yield percentage, texture, acidity, chlorophyll, and carotenoid (P > 0.05). The best exposure for CAP treatment was 60 s since it increased phenolic compounds, antioxidant activity, and vitamin C content in the lime juice.

Effect of Physical Modifications on Physicochemical and Functional Properties of Walnut Protein.

Walnut protein is a high-quality vegetable protein with promising applications in the food industry; however, its potential is hindered by low solubility and associated properties. We utilized various physical modification techniques (cold plasma; ball milling; superfine grinding; ultrasound; wet ball milling; and high-pressure microjet) to enhance walnut proteins' physicochemical and functional properties. The changes in particle size, microstructure, surface hydrophobicity, fluorescence, solubility, foaming, and emulsification were investigated. Cold plasma and ultrasound treatments minimally affected particle size and morphology. Cold plasma increased the particle size D4,3 from 145.20 μm to 152.50 μm. Ultrasonication reduced the particle size D4,3 to 138.00 μm. The variation was within ±10 μm, while the particle size of walnut protein significantly decreased after the other four modification treatments. The greatest variation in particle size was in the superfine grinding, with the D4,3 being reduced to 23.80 μm. Ultrasound treatment converted the β-sheet into an α-helix, while the other methods transformed the α-helix into a β-sheet. The dispersion stability notably improved after wet ball milling and high-pressure microjet treatments, which was accompanied by a significant increase in solubility from 6.9% (control) to 13.6% (wet ball milling) and 31.7% (high-pressure microjet). The foaming and emulsification properties were also enhanced through these modifications (foaming improved from 47% to 55.33% and emulsification improved from 4.32 m2/g to 8.27 m2/g). High-pressure microjet treatment proved most effective at improving solubility in the functional properties of walnut protein. These findings are expected to help broaden the potential utilization of walnut protein in the food industry, including in beverages and emulsions.

Effect of plasma processing gas on Ara h 1 in peanut protein extract

Peanut allergen Ara h 1 is one of the most common food allergens in the world, and it is highly allergenic owing to its stable structure. Cold plasma is an emerging non-thermal processing technology that generates reactive radicals that enable the rapid degradation of allergenic protein. In this study, the effectiveness of two plasma treatment gases on the inhibition of the Ara h 1 allergen in peanut protein extract was investigated as the gases were expected to react with the allergen differently. The results revealed that the antigenicity of Ara h 1 decreased by approximately 55% after 13 min of cold plasma treatment. This may be attributed to the destruction of the α-helix structure. In addition, compared to air cold plasma treatment, nitrogen plasma treatment only caused less than one third of oxidative damage to the samples. In summary, air and nitrogen plasmas are both effective in reducing peanut allergen Ara h 1, but the peanut maintained most of its original quality after nitrogen cold plasma treatment. The result of this study demonstrated that nitrogen cold plasma is a great candidate for reducing Ara h 1 for effective food processing.

Effects of in-package cold plasma treatment on the physicochemical and oral toxicological properties of raw grape tomatoes and the probability of salmonellosis from consumption of the tomatoes

Effects of in-package cold plasma treatment on the physicochemical and oral toxicological properties of raw grape tomatoes and the probability of salmonellosis from consumption of the tomatoes