Hydra as a Model for Screening Ecotoxicological Effects of Plasma-Treated Water

Atmospheric cold plasma (ACP) has been widely researched to generate functionalized solutions for decontamination of liquids and wastewater treatment. The present investigation demonstrates that Hydra can be used as an additional in vivo tool to monitor the impact of plasma-processed solutions on the aquatic environment

Dissipation of Pesticide Residues on Grapes and Strawberries Using Plasma-Activated Water

In this study, we present a novel atmospheric air plasma discharge for the generation of plasma-activated water (PAW), with the aim of reducing pesticide residues on fresh fruit. For this purpose, a large discharge volume pin-to-plate cold plasma reactor was employed. The pesticide-spiked grapes and strawberries were processed with varying PAW concentrations to study their efficacies for pesticide degradation combined with an evaluation of any induced changes in key nutritional and quality attributes. The results suggest that the reduction of chlorpyrifos was 79% on grapes and 69% on strawberries while that of carbaryl was 86% on grapes and 73% on strawberries, respectively. The degradation of pesticides in PAW is due to the generation of metastable reactive species including nitrates, nitrites, and hydrogen peroxide. The high oxidation potential and acidic environment of this PAW are proposed as important actors for pesticide dissipation. In addition to the effective pesticide reductions obtained, there were no significant changes in the key physical attributes (color and firmness) of the treated samples and only slight changes in the ascorbic acid levels observed for both strawberries and grapes. This study points to the effective potential of PAW for chemical decontamination of fruit while maintaining important quality and nutritional parameters

Effect of cold plasma treatment on the antigenicity of peanut allergen Ara h 1

The objective of this study was to investigate the effects of cold atmospheric plasma on the antigenicity of protein Ara h 1. Dry, defatted peanut flour (DPF), whole peanut (WP) were subjected to cold atmospheric plasma at voltage of 80 kV for different treatment durations (0, 15, 30, 45 and 60 min). The allergen samples were analyzed using SDS-PAGE, immunoblot and competitive ELISA. Furthermore, the secondary structure was examined using circular dichroism. SDS-PAGE results revealed no change in the protein intensity bands corresponding to Ara h 1 for both DPF and WP. Competitive ELISA of samples showed a reduction in antigenicity up to 43% for DPF and 9.3% for WP. Circular dichroism studies revealed modifications in secondary structure induced by plasma reactive species. Industrial relevance Cold plasma has emerged as a novel processing technique. This study provides evidence for reduction of antigenicity of Ara h1 in peanuts using cold plasma. This study also demonstrated the plasma-induced changes in protein structure at high treatment duration. The work described in this research is relevant to the processing of cereal grains and legumes wherein allergenicity is a major concern. This results provide the basis for possible industrial implementation

Humic Acid and Trihalomethane Breakdown with Potential By-Product Formations for Atmospheric Air Plasma Water treatment

Over the past century chlorine has been widely used as an oxidant in water and wastewater treatment. Chlorine’s efficacy is demonstrated for microbial inactivation of a wide variety of pathogens along with oxidation of various chemical contaminants. However, the potential formation of disinfection by-products (DBPs), such as trihalomethane, is a concern [1]. DBPs, including trihalomethanes, can be formed as a consequence of the reaction of chlorine with natural organic matter (NOM) present in both surface and ground water [2]. NOM comprises of two fractions; humic substances (HS), which are composed of humic acids, fulvic acids, and non-humic substances (non-HS), which include carbohydrates, lipids, and amino acids [3]. Furthermore, humic acids constitute a major fraction of NOM, of which the soluble portion (aromatic compounds) of humic substances may react with chlorine to form trihalomethanes [4]. It has been reported that these THMs are carcinogens [5]. Epidemiologic studies in humans suggest a weak association with bladder, rectal and colon cancer [6,7] along with reproductive and developmental effects [8,9]. Due to these health concerns, many jurisdictions specify maximum allowable concentrations. The United States Environ- mental Protection Agency [10] specifies maximum levels for trihalomethanes (THMs) and haloacetic acids (HAAs) of 80 and 60 mg/L, respectively [11]. European Union regulations limit THMs to 100 mg/L. However, many national reports find frequent occurrence of THM exceedance [12]. It is important to limit THMs and THMs causing substances (humic acids) in water. Several approaches such as nanofiltration, ultrafiltration, reverse osmosis coagulation [13], activated carbon adsorption [14], Fenton treatment [15], nano-TiO2 photocatalysis [16], membrane filtration [17], biological treatment [18], and ozonation [19] have been employed to remove humic substances and THM’s. Biological processes, including the use of bio-filters may lead to the accumulation of suspended solids and release of bacteria [20]. Separation technologies such as biofilms and membrane filtration may be limited due to fouling [21]. Ozone’s efficacy for humic substance breakdown in water has been demonstrated, however the process may result in the formation of brominated by-products [22]. In addition, the use of such advanced oxidation processes (AOP) which are capable of oxidizing some of the NOM present in raw water sources require an additional step for mineralization increasing the operational cost. Therefore, there is a need to develop novel approaches to remove humic substances and THMs in energy efficient manner

Impact of Cold Plasma Processing on Major Peanut Allergens

Cold plasma is emerging as a novel food processing technology, with demonstrated efficacies for microbial inactivation and residual chemical dissipation of food products. Given the technology’s multimodal action it has the potential to reduce allergens in foods, however data on the efficacy and mechanisms of action are sparse. This study investigates the efficacy of cold plasma on major peanut allergens (Ara h 1 and Ara h 2). For this purpose, dry, whole peanut (WP) and defatted peanut flour (DPF) were subjected to an atmospheric air discharge using a pin to plate cold plasma reactor for different treatment durations. With increases in plasma exposure, SDS‑PAGE analysis revealed reduced protein solubility of the major peanut allergens. Alterations in allergenicity and structure of Ara h 1 and Ara h 2 were examined using ELISA and circular dichroism (CD) spectroscopy. Competitive ELISA with proteins purified from plasma treated WP or DPF revealed reduced antigenicity for both Ara h 1 and Ara h 2. The highest reduction in antigenicity was 65% for Ara h 1 and 66% Ara h 2 when purified from DPF. Results from CD spectroscopy analysis of purified proteins strongly suggests the reduction in antigenicity is due to modifications in the secondary structure of the allergens induced by plasma reactive species. Cold plasma is effective at reducing peanut protein solubility and causes changes in allergen structure leading to reduced antigenicity

Efficacy and mechanistic insights into endocrine disruptor degradation using atmospheric air plasma

Endocrine disruptors are a class of contaminants found in water and process effluents at low concentrations. They are of concern due to their high estrogenic potency. Their presence in the environment has led to the search for effective techniques for their removal in wastewater. For this purpose, an atmospheric air plasma reactor was employed for the study of the degradation of three endocrine disruptor chemicals (EDC) namely; bisphenol A (BPA), estrone (E1) and 17β-estradiol (E2) within a model dairy effluent. Identification of the plasma induced active species both in the gas and liquid phases were performed. Also studied was the influence of an inhibitor, namely tertiary butanol, on the degradation of the EDCs. The results demonstrate that air plasma could successfully degrade the tested EDCs, achieving efficacies of 93% (k=0.189min−1) for BPA, 83% (k=0.132min−1) for E1 and 86% (k=0.149min−1) for E2, with the process following first order kinetics. The removal efficacy was reduced in the presence of a radical scavenger confirming the key role of oxygen radicals such as OH in the degradation process. The intermediate and final products generated in the degradation process were identified using UHPLC-MS and LC-MS. Based on the intermediates identified a proposed degradation pathway is presented

Diagnostics of a Large Volume Pin-to-Plate Atmospheric Plasma Source for the Study of Plasma Species Interactions with Cancer Cell Cultures

A large gap pin-to-plate, atmospheric pressure plasma reactor is demonstrated as means of in vitro study of plasma species interactions with cell cultures. By employing optical emission and optical absorption spectroscopy, we report that the pin-to-pate plasma array had an optimal discharge frequency for cell death of 1000 Hz in ambient air for the target cancer cell line; human glioblastoma multiform (U-251MG). The detected plasma chemistry contained reactive oxygen and nitrogen species including OH, N2, N2+, and O3. We show that, by varying the plasma discharge frequency, the plasma chemistry can be tailored to contain up to 8.85 times higher levels of reactive oxygen species as well as a factor increase of up to 2.86 for levels of reactive nitrogen species. At higher frequencies, reactive oxygen species are more dominant than reactive nitrogen species which allows for a more dynamic and controlled environment for sample study without modifying the inducer gas conditions. When used for treatment of culture media and cell cultures, variation of the plasma discharge frequency over the range 1000-2500 Hz demonstrated a clear dependence of the responses with the highest cytotoxic responses observed for 1000 Hz. We propose that the reactor offers a means of studying plasma-cell interactions and possible co-factors such as pro-drugs and nano particles for a large volume of samples and conditions due to the use of well plates

Effect of Atmospheric cold Plasma on the Functional Properties of Whole Wheat (Triticum aestivum L.) Grain and Wheat Flour

Atmospheric cold plasma (ACP) has emerged as a novel processing technology, with demonstrated efficiencies in microbial inactivation. However, studies on the effects of ACP and potential to modify the functional properties of foods are sparse. The objective of this study is to determine the effect of ACP on physico-chemical and functional properties of wheat flour. In this study, both whole wheat grains and wheat flour were subjected to a dielectric barrier discharge (DBD) contained plasma reactor for a range of treatment times (5–30 min) at 80 kV. Plasma treatment increased the flour hydration properties of wheat flour. Rapid visco-analyser results showed an increase in pasting and the final viscosities of wheat flour. The decrease in both endothermic enthalpies and crystallinity was attributed to the depolymerization of starch and plasma-induced changes. Overall DBD-ACP treatment can be tailored to develop a plasma process with potential to improve functionality of wheat flour

Ferric Chloride Assisted Plasma Pretreatment of Lignocellulose

In this study, a novel pretreatment for spent coffee waste (SCW) has been proposed which combines two techniques viz. atmospheric air plasma and FeCl3 to create a superior pretreatment that involves Fenton chemistry. The pretreatment was optimised employing Taguchi Design of Experiments, and five parameters were taken into consideration viz. biomass loading, FeCl3 concentration, H2SO4 concentration, plasma discharge voltage and treatment time. The composition analysis of the pretreated SCW revealed substantial amounts of lignin removal, with a maximum for process conditions of 70kV for 2min in an acidic environment containing 1% H2SO4. FTIR, XRD and DSC were performed to characterise the samples. The pretreated SCW after enzymatic hydrolysis yielded 0.496g of reducing sugar/g of SCW. The hydrolysate was subjected to fermentation by S. cerevisiae and led to the production of 18.642g/l of ethanol with a fermentation efficiency of 74%, which was a two-fold increase in yield compared to the control

Characterisation of Cold Plasma Treated Beef and Dairy Lipids Using Spectroscopic and Chromatographic Methods

The efficacy of cold plasma for inactivation of food-borne pathogens in foods is established. However, insights on cold plasma-food interactions in terms of quality effects, particularly for oils and fats, are sparse. This study evaluated plasma-induced lipid oxidation of model matrices, namely dairy and meat fats. Product characterisation was performed using FTIR, 1H NMR and chromatographic techniques. The oxidation of lipids by cold plasma followed the Criegee mechanism and typical oxidation products identified included ozonides, aldehydes (hexanal, pentenal, nonanal and nonenal) and carboxylic acids (9-oxononanoic acid, octanoic acid, nonanoic acid), along with hydroperoxides (9- and 13-hydroperoxy-octadecadienoylglycerol species). However, these oxidation products were only identified following extended treatment times of 30 min and were also a function of applied voltage level. Understanding cold plasma interactions with food lipids and the critical parameters governing lipid oxidation is required prior to the industrial adoption of this technology for food products with high fat contents