Gaseous Ozone Treatment Research Articles

Effect of Gaseous Ozone and Hydrogen Peroxide Treatment on the Polyphenolic Profile of Tomato Fruits Grown Under Cover

The aim of the study was to determine the effect of gaseous ozone, hydrogen peroxide and both factors used alternately on the profile of phenolic compounds of tomato fruits grown under cover. Phenolic compounds are natural substances, and their biosynthesis in plant tissues is affected by stress factors such as gaseous ozone and hydrogen peroxide. The experiment showed that the use of gaseous ozone at a dose of 2 ppm for 1.5 and 3 min significantly increased the total amount of phenolic compounds in tomato fruits compared to the control. In turn, in fruits obtained from plants to which hydrogen peroxide was applied at a concentration of 1 and 3% during vegetation, a lower amount of phenolic compounds was found compared to the control. In addition, the combined use of ozone and hydrogen peroxide in the case of four variants—2 ppm for 1.5 min + 1% H2O2; 2 ppm for 3 min + 1% H2O2; 2 ppm 1 min + 3% H2O2; 2 ppm 3 min + 3% H2O2—significantly increased the amount of phenolic compounds compared to the control.

Room temperature oxygenated groups addition in carbon materials via ozone oxidation for boosting electrochemical H2O2 production

The crucial yet delicate 2e− oxygen reduction reaction (ORR) for producing the green chemical H2O2 relies on the uniform coordination environment of the active sites, such as oxygenated groups in metal-free carbon material catalysts. However, conventional harsh carbon material synthesis methods inevitably introduce structural defects and alter morphology, hindering the precise control of active site formation. Herein, we developed the ozone oxidation method under controlled reaction conditions to precisely modify carbon materials at room temperature. Through controlling the ozonation of reaction time, concentration, temperature, and relative humidity, we find the mild method allows us to precisely add active carboxyl group (–COOH) without forming structural defects. Electrochemical tests reveal that the optimal catalyst with the highest –COOH content exhibits the most outstanding mass activity of 164 A/g at 0.65 V and the highest H2O2 selectivity of 91 %. The density functional theory calculations demonstrate that the carbon sites directly connected to –COOH possess the optimized binding strength of *OOH intermediate to favor the two-electron oxygen reduction process. This work offers a novel approach to precisely and gently control carbon surface groups while preserving the structural morphology through ozone gas treatment, which can be readily applied to other material designs.

Effect of Ozone on Enterobacteriaceae Counts in Wheat Grain, Alfalfa, Radish, Broccoli Seeds and Sprouts

Abstract The sprouts of various seeds have garnered considerable regard amid consumers due to its verdure, crispiness, and germination potential, offering a cost-effective and straightforward process. The moist and warm conditions are very conducive to germination, fostering the growth of microorganisms and thereby raising food safety concerns. The aim of the study was to investigate the impact of ozone on Enterobacteriaceae counts by subjecting wheat (Triticum aestivum) grains, alfalfa (Medicago sativa), radish (Raphanus sativus) and broccoli (Brassica oleracea) seeds to ozone gas treatment. Additionally, the grain and seeds were rinsed with ozonated water during germination. Three different treatment methods were employed for seeds and grains. In the first method, samples were exposed to ozone gas at 20 ppm for 10 minutes, with subsequent rinsing every 12 hours during germination until the rinse water appeared visually clean, at a concentration of 2.0 mg L−1 of ozone. The second method involved rinsing with ozonated water at a concentration of 2.0 mg L−1 for durations of 20, 40, and 60 minutes. The third method - treated with ozone gas at 50 ppm and the exposure time of 1, 2, 3, 4 and 5 h. Untreated samples were used as controls. Evaluation of the samples revealed that Enterobacteriaceae was virtually undetectable in dry seeds. However, after 72 hours of germination in both the control and ozone-treated sprouts and following 7 days of storage at 4±2 °C, Enterobacteriaceae were found at an average of 7 to 8.1 log CFU g−1 in all samples, irrespective of the treatment method. Additionally, mould was observed only in wheat and radish sprouts during the assessment period. The study showed that there was no significant reduction in the number of mesophilic aerobic and facultative anaerobic microorganisms, moulds and Enterobacteriaceae then treated with ozone gas.

Ozone Treatment as a Sustainable Alternative for Suppressing Blue Mold in Mandarins and Extending Shelf Life

Citrus fruits, particularly mandarins, are highly valued globally for their nutritional benefits and versatile culinary uses. However, the challenge of post-harvest decay, primarily due to blue mold (Penicillium italicum) infections, results in significant food losses and necessitates effective preservation strategies. Traditional methods often rely on fungicides, raising concerns about chemical residues and environmental impact. This study investigates the efficacy of ozone as an alternative approach to controlling blue mold in mandarins. Various gaseous ozone treatments were tested, including single, double, and triple treatments, with durations ranging from 10 to 60 min and concentrations from 3.3 to 20 ppm. Additionally, ozonated water treatments were evaluated with concentrations of 2, 4, and 6 ppm. To simulate a realistic infestation scenario, mandarins were artificially infected with P. italicum spores before undergoing both gaseous ozone and ozonated water treatments. The storage conditions for the mandarins were meticulously controlled, maintaining a humidity level of 50–60% and a temperature range of 10–12 °C. Each fruit was analyzed, and the presence of P. italicum infection was determined two and three weeks after the ozonation. Results indicated that ozone treatments significantly reduced mold growth, with gaseous ozone demonstrating efficacy rates up to 97.5% and ozonated water treatments achieving preservation rates between 95% and 97%. These results underscore ozone’s potential as a safe, efficient, and sustainable alternative to conventional fungicides, offering promising solutions for extending the shelf life of mandarins. Further research is recommended to optimize ozone treatment parameters, assess long-term effects on fruit quality and nutritional content, and refine application techniques to harness ozone’s potential in citrus fruit preservation fully. This approach not only addresses food security challenges but also aligns with global efforts to reduce chemical inputs in agriculture and promote environmentally sustainable practices.

Effects of High Concentration-Short Time and Low Concentration-Long Time Ozone Treatments on Growth and Aflatoxin B1 Production of Aspergillus flavus in Red Pepper

ABSTRACT The effects of high concentration-short time (HCST) and low concentration-long time (LCLT) gaseous ozone treatments on growth and aflatoxin B1 production of Aspergillus flavus in semi-dried red pepper are presented for the first time in this paper. Potato dextrose agar (PDA) media and peppers were inoculated with a toxigenic strain of A. flavus and exposed to either HCST (1500 μL L−1 for 1–8 h) or LCLT (0.1 μL L−1 for 8 d) ozone treatments. Both treatments significantly inhibited A. flavus growth in PDA and peppers (p < 0.05). In pepper samples, fungal count reductions obtained by HCST and LCLT ozone treatments were around 1.57 and 1.66 log, respectively. However, the inhibitory effect decreased in time which shows that the fungus rapidly develops a resistance to ozone. The amounts of aflatoxin B1 produced in PDA and pepper were also significantly reduced (by more than 85%) by the treatments (p < 0.05). These results demonstrate the potential of ozone treatments in preventing fungal contamination and aflatoxin production in red pepper.

Evaluation of the effect of ozone disinfection on forensic identification of blood, saliva, and semen stains

Good laboratory practice minimizes the biological hazard posed by potentially infectious casework samples. In certain scenarios, when the casework sample is contaminated with highly contagious pathogens, additional safety procedures such as disinfection might be advised. It was previously proven that ozone gas treatment does not hamper STR analysis, but there is no data on how the disinfection affects other steps of the forensic analysis.In this study, we aimed to assess the interference of ozone disinfection with forensic tests used to identify biological stains.A dilution series of blood, saliva, and semen samples were pipetted onto cotton fabric and let completely dry. Half of the samples were subjected to ozone treatment, while the rest served as controls. All the samples were tested with specific lateral flow immunochromatographic assays and for specific RNA markers with quantitative real-time PCR. Additionally, luminol test was carried out on blood spots, Phadebas® Amylase Test on saliva stains, and semen stains were examined with STK Lab kit and light microscope following Christmas Tree or Hematoxylin-Eosin staining.Ozone treatment had no detrimental effect on the microscopic identification of sperm cells. Undiluted blood samples were detected with luminol and immunoassay, but at higher dilution, the sensitivity of the test decreased after disinfection. The same decrease in sensitivity was observed in the detection of semen stains using STK Lab kit from STK® Sperm Tracker, and in the case of the immunoassay specific for prostate-specific antigen (PSA). Ozone treatment almost completely inhibited the enzymatic activity of amylase. The sensitivity of antibody-based detection of amylase was also greatly reduced. RNA markers showed degradation but remained detectable in blood and semen samples after incubation in the presence of ozone. In saliva, the higher Ct values of the mRNA markers were close to the detection limit, even before ozone treatment.

Mechanism of ozone treatment in delayed softening of fresh-cut kiwifruit during storage

Firmness is one of the most important factors affecting the quality and commercial value of fresh-cut kiwifruits. The aim of this study was to investigate the effects of 1 mg/L of gaseous ozone treatment for 10 min on the texture of fresh-cut kiwifruit stored at 4 °C for 12 d. Ozone treatment relatively maintained the firmness of the fresh-cut fruit for 12 d compared with the untreated group. Laser scanning confocal microscopy (LSCM) showed that endogenous free Ca2+ was higher and more evenly distributed in ozone-treated fruits than in the untreated group, and correlation analysis indicated that the higher the Ca2+ concentration, the greater the formation of Ca-pectinate. Additionally, ozone treatment inhibited the activity of cell wall polysaccharide-degrading enzymes, suppressed electrolyte leakage and malondialdehyde and hydrogen peroxide contents, and maintained protopectin and cellulose levels, thereby preventing fruit softening. Overall, these results showed that ozone treatment delayed the softening of fresh-cut kiwifruit by increasing endogenous Ca2+ concentrations and preventing polysaccharide solubilization.

Photochemical advanced oxidative process treatment effect on the pesticide residues reduction and quality changes in dried red peppers

Pesticide residues in crops are widely monitored, and the residue reduction techniques at the post-harvest stage are important to maintain food safety. In dried crops, pesticide residues can be concentrated after dehydration, which increases concerns regarding residue risk. Therefore, the residue reduction effects of ultraviolet (UV), ozone, and photochemical advanced oxidative process (pAOP) were investigated for dried peppers at the post-harvest stage. UV254 treatment reduced 59.7% of the residue concentration on average, while UV360 showed a reduction of only 13.3% under 9.6 W m−2 of UV exposure for 24 h. Gaseous ozone treatments reduced the residue concentrations up to 57.9% on average. In contrast, the pAOP treatment reduced the concentration up to 97% and was superior to UV or ozone treatment alone. Increased drying temperature under pAOP condition resulted in higher reduction ratios at 40–80 °C. The pAOP conditions with 12 and 24 µmol/mol of ozone and UV254 irradiation for 24–48 h reduced the residue concentrations to 39–67%. Particularly, difenoconazole, fludioxonil, imidacloprid, and thiamethoxam residue concentrations were drastically reduced by over 50% under 12 µmol/mol ozone of the pAOP condition, while carbendazim, fluquinconazole, and pyrimethanil were relatively stable and their concentrations reduced below 50% under 24 µmol/mol ozone of the pAOP treatment. Various drying-related quality parameters of drying peppers such as water-soluble color, capsanthin, capsaicinoids, acid value, peroxide value, and thiobarbituric acid value were slightly altered, but not significantly, under 12 µmol/mol ozone of the pAOP condition, while the peroxide value was significantly altered under the higher ozone conditions. Therefore, pAOP treatment combined with gaseous ozone can be used for reducing residual pesticides in peppers without greatly reducing quality.

Inactivation of nontuberculous mycobacteria by gaseous ozone treatment

Nontuberculous mycobacteria (NTM) are environmental bacteria resistant to many common disinfectants and ultraviolet radiation. Inhalation of aerosols generated from NTM-containing water and soil causes NTM lung disease, especially in people with underlying lung diseases and decreased immunity. To prevent healthcare-acquired NTM infections, it is important to eradicate NTM living in hospital environments. Therefore, we evaluated the efficacy of gaseous ozone for the inactivation of NTM, namely Mycobacterium (M.) avium, M. intracellulare, M. kansasii, M. abscessus subsp. abscessus and M.abscessus subsp. massiliense. Gaseous ozone treatment at 1 ppm for 3 h reduced the bacterial number of all strains by more than 97%. Gaseous ozone treatment could be a practical, effective and convenient disinfection method for NTM living in hospital environments.

Creep behaviour of ozone treated jute fabric/epoxy composites

The present work attempted to study the creep behaviour of jute fabric/epoxy composites at different environment temperatures using several creep models (i.e., Burger’s model, Findley’s power law model, and Coupling model). The surface of jute fabrics was modified by ozone gas treatment to remove the non-cellulosic materials and thereby improve their adhesion with epoxy matrix. Further, the performance of ozone surface treatment was compared with traditional alkali treatment based on surface morphology, mechanical properties, hydrophilicity, etc. The ozone surface treatment was found to remove lignin and increase hydrophilicity of jute fibres to greater extent as compared to alkali treatment, however with higher tendency of defibrillation and fibre rupture. Later, the creep resistance of alkali treated jute fabric/epoxy composites was found superior to the ozone treated jute fabric/epoxy composites at lower temperature of 40°C and 70°C. However, the ozone treated jute fabric/epoxy composites showed higher instantaneous elastic deformation and lower viscous deformation at elevated temperatures of 70°C and 100°C. The ozone treated jute fabric/epoxy composites showed extended temperature range of 100°C–120°C to restrict segmental mobility of epoxy matrix and depicted higher interfacial shear strength properties from the microbead pull out test.

Gaseous ozone regulates reactive oxygen species metabolism and ascorbate–glutathione cycle to delay the senescence of fresh-cut red pitaya (Selenicereus undatus) fruit

Mechanical damage during processing can accelerate the senescence and deterioration of fresh-cut red pitaya (Selenicereus undatus), thereby affecting its nutritional quality and commodity value. In this study, the effects of a low-concentration and long-term (10 μL L−1 for 60 min) gaseous ozone treatment on the quality, reactive oxygen species (ROS) metabolism, and enzyme and non-enzyme antioxidant activities of fresh-cut red pitaya fruit were investigated. The results showed that ozone treatment delayed the decline in fruit firmness, total soluble solids, and titratable acid content. Ozone treatment also maintained a higher free radical scavenging capacity and lower membrane lipid peroxidation than the control treatment. It prevented the rapid increase in ROS level by improving the activity of antioxidant enzymes, including superoxide dismutase, peroxidase, and catalase. Additionally, the treatment activated the ascorbate–glutathione cycle. Compared with the control group, ozone treatment maintained the activities of ascorbic acid peroxidase, dehydroascorbic acid reductase, monodehydroascorbic acid reductase, and glutathione reductase. Although the contents of ascorbic acid (AsA) and dehydroascorbic acid (DHA) decreased within 10 days of storage, the AsA/DHA and glutathione/oxidized glutathione ratios in the ozone-treated group were higher than those in the control group from day 0 to day 6. Thus, ozone treatment regulated ROS metabolism, enhanced the ROS-scavenging system, maintained the redox balance of fresh-cut red pitaya, and delayed senescence.

EFFECTS OF GASEOUS OZONE TREATMENT ON THE MITE PEST CONTROL AND QUALITATIVE PROPERTIES DURING RIPENING STORAGE OF PECORINO CHEESE.

Ripened cheeses, such as Pecorino, are susceptible to mites and molds contamination on the crust area that must be removed before the product can be marketed. This research investigates the effectiveness of gaseous ozone treatment in the control of microbiological and mite growth without negatively affecting product quality. Cheese samples were treated with gaseous ozone at 200 and 300 ppb for 8 hours per day (overnight) for 150 days in storage rooms under controlled conditions (12 °C and 85% R.H.). The results showed that ozone at 200 ppb limits the growth of mites starting from 25 days of storage and significantly reduced bacteria, molds and yeasts count starting from 75 days of storage. Concerning the physicochemical and qualitative parameters evaluated during ripening (weight loss, moisture content, dry weight, ash, fat, protein, total nitrogen, color, non-destructive firmness), no significant differences were shown between the control samples and ozone treatment at 200 ppb. Sensory analysis (consumer test) also showed no specific defects with the ozone-treated samples. It was observed that the ozone treatment at 300 ppb had limited microbiological growth and no alteration of sensory aspects but did not have the same positive impact on some aspects of overall quality, compared to ozone treatment at 200 ppb. The use of gaseous ozone treatments during ripening of Pecorino cheese can potentially offer an excellent solution for the control of mite growth, while preserving the quality and sensory characteristics of the product. For this reason, this technique could be very useful for commercial purposes. This article is protected by copyright. All rights reserved.

Influence of ozone treatment on wheat (Triticumaestivum) germination during bulk storage

The currentexperiment was conductedto understandgaseous ozone exposure time and cycle effect on wheat seed germination during storage. The bulk storage of wheat grain hasa major issue of insects and pests which is controlled by gaseous ozone treatment in closed storage system. Ozone is the acceptable and economically viable technique for treating grains during storage for its residue-free and environment-friendly nature. In this research article, the ozone gas treatment givento the wheat grain during bulk storage and evaluated its influence on seed germination.A pilot-scale ozone disinfestation system for wheat grains was developed. The two-factorial experimental design on the influence of the parameters of the technological process of ozone treatment on the germination qualities of wheat seeds was carried out. Wheat grains were treated by gaseous ozone with various time durations (0 min, 30 min, 60 min, 90 min and 120 min) and at various frequency cycles (7 days, 14 days, 21 days). The experiment has recorded observation on the effect of ozone treatment time and the ozone frequency cycle on the germination percentage of wheat grain.The data demonstrated that ozone used in bulk storage enhances seed germination percentage. On the other hand, excess ozone can also cause some negative effects on germination. This study provided new insights into how stored wheat grain responds to ozone treatment and highlighted the impact of treatment time durations and frequency cycle for seed germination.

Effects of gaseous ozone treatment on the quality and microbial community of salmon (Salmo salar) during cold storage

To elucidate the effect of gaseous ozone with different dose and exposing time (A and B: 1 mg/m 3 or 3 mg/m 3 for 5 min; C and D: 1 or 3 mg/m 3 for 10 min, respectively, corona discharge method) on the quality of salmon, the microbial growth, lipid oxidation, color, odor characteristics, microbiota, and the correlations between them were studied. The results showed that the total viable counts of groups C (6.05 log CFU/g) and D (5.71 log CFU/g) were lower than the control (7.08 log CFU/g) on day 10. The ozone treatment also retarded the increase of total volatile basic nitrogen (TVB-N), thiobarbituric acid substances (TBARS), and drip losses as well as the decrease of sensory scores. Though the ozonated treatment led to a slight decrease of a * value, it could deodorize the fishy smell. The results of next-generation sequencing showed that the relative abundance of Photobacterium decreased after treatments, but recovered during storage, and it was the predominant bacteria causing the deterioration of salmon fillets according to the correlation analysis with sensory score, TVB-N, and TBARS values. The results demonstrated that gaseous ozone was a promising method for salmon preservation, and the exposing time had a greater effect on the salmon quality than the ozone concentrations in this study. The ozonation treatment with the dose of 1 or 3 mg/m 3 for 10 min was recommended for salmon fillets. • Photobacterium was the main bacteria causing the quality deterioration of salmon. • Gaseous ozone reduced the relative abundance of Photobacterium after treatment. • The exposing time had a greater effect on the salmon quality than the ozone dose. • The optimal ozonation treatment for salmon was 1 or 3 mg/m 3 for 10 min. • The deodorizing effect of ozone may relate to the ozonolysis of fatty acids.

Gaseous ozone treatment prolongs the shelf-life of fresh-cut kiwifruit by maintaining its ascorbic acid content

Ascorbic acid (AsA) is a non-enzymatic antioxidant abundant in kiwifruit. However, physical injuries and long-term storage can decrease the AsA content and shorten shelf-life of fresh-cut kiwifruit. This study confirmed that treatment with 1 mg/L ozone for 10min was an effective fresh-keeping strategy, as indicated in alleviating AsA loss, promoting antioxidant capacity and inhibiting bacterial growth, thereby prolonging the shelf-life of fresh-cut kiwifruit. The results revealed that ozonized kiwifruits exhibited higher AsA content by increasing glutathione (GSH) content and promoting activities of key enzymes included in the AsA-GSH cycle. Particularly, the related enzymes regulating AsA content were changed after day 6. Meanwhile, ozone increased the total flavonoid content (TFC) and the total phenolic content (TPC) since AsA content was significantly correlated to TPC and TFC, as revealed by correlation analysis. In conclusion, the application of ozone can be used to maintain the commercial and consumptive value of fresh-cut fruits over an extended time.

Gaseous ozone treatment of chickpea grains: Effect on functional groups, thermal behavior, pasting properties, morphological features, and phytochemicals.

The applicability of ozone has been increased to include pulse grains because of their increased production and significance as plant-based protein source. In many developed countries, there is a growing demand for products made from chickpeas grains. Whole chickpea grains were treated with ozone gas (500-1000ppm) for 20-30 min. The structural, thermal, pasting properties, and phytochemicals of the ozone-treated, as well as control samples, were evaluated. Minor structural changes in the functional groups in the protein and starch molecules were observed in the treated sample. Ozonation caused significant changes in the pasting properties such as peak viscosity, trough viscosity, breakdown viscosity, final viscosity, setback viscosity, and peak temperature values. Microstructure revealed a reduction in the particle sizes of chickpea powders with the severity of ozone treatment. The total flavonoids (41.35-48.94mg QE), alkaloids (1120.24-1453.57µg/g), and xanthoprotein (0.995-1.387µg/g) increased significantly (p<0.05) with ozone treatment. Commercially, chickpea grains can be ozone treated for achieving desired functional characteristics in a target product. PRACTICAL APPLICATION: Before consuming grain that has been treated with gaseous ozone, it is vitally important for all consumers to have a solid understanding of the facts presented here regarding variations in the chickpea nutritional profile. The impact of ozone treatment on functional groups, thermal behavior, pasting properties, and morphological features in chickpeas reveals vital information regarding changes occurred on macromolecules such as starch, proteins, and bioactive compounds. Since ozonation aids in extraction of health-beneficial bioactive compounds and brings about change in the starch and protein morphology, making them more digestible, it can be highly useful in preparation of health foods.

Use of gaseous ozone in soft cheese ripening: Effect on the rind microorganisms and the sensorial quality

The uncontrolled growth of potential spoilage microorganisms in cheese surfaces can deteriorate cheese quality, especially filamentous fungi. This study aimed to evaluate the effect of several gaseous ozone treatments during the ripening of soft cheese on the growth of cheese rind microorganisms at different production scales. On a pilot plant scale, the cheeses were inoculated with potential spoilage microorganisms (Mucor plumbeus, Kluyveromyces marxianus, and Pseudomonas fluorescens), while on an industrial scale, naturally present microorganisms were evaluated. Ozone treatments showed a considerable fungistatic effect on cheese surface molds at both pilot and industrial scale. However, the effect of ozone on yeast growth was only observed at pilot plant scale, while Pseudomonas ssp. was not affected by the ozone concentrations used in this study. The sensory quality of the cheese was also assessed. Cheese typicality was not affected by gaseous ozone. However, the ozonized samples had significantly higher scores than the control samples for rind appearance and color. Hence, ozonation can be considered an alternative approach to control mold growth in soft cheese during ripening and prevent cheese rind discoloration.

Influence of ozonation and roasting on functional, microstructural, textural characteristics, and aflatoxin content of groundnut kernels.

The present study was conducted to evaluate the influence of ozonation, roasting and their combination on the moisture content, color, functional, structural, textural components, and aflatoxins in groundnut kernels. Samples were subjected to three treatments namely, dry roasting (R): 166°C for 7min; gaseous ozone treatment (O): 6mg/L for 30 min; combined ozonation-roasting (OR): gaseous ozonation at 6mg/L for 30 min followed by dry roasting at 166°C for 7min. The ozonated-roasted samples had the lowest moisture content (3.45%), the highest total phenolic content (4.18 mg gallic acid equivalents/100 g), and antioxidants capacity (69.59%). The treatments did not induce significant changes in color of kernels (p< .05). Scanning electron microscopy indicated cracking of granules in roasted and swelling in ozonated kernels whereas more uniform orientation of granules was observed in ozonated-roasted kernels. Roasted and ozonated kernels indicated a significant reduction of fracturability force to 54.60 and 14.11%, respectively, whereas ozonated-roasted samples demonstrated a nonsignificant increase (4.37%). An increase in wave number of ozonated samples to 3,289.37 cm-1 in Fourier transform infrared (FTIR) spectrum (FTIR) indicated stretching in OH groups. FTIR spectrum of ozonated-roasted kernels suggested the formation of a new compound with CC and CC groups. The major aflatoxin B1 was reduced to maximum, that is, 100% in ozonated-roasted kernels followed by ozonated (80.95%) and roasted (57.14%) samples. The findings indicate that the ozonation-roasting treatment had a prominent role in the enhancement of functional compounds, structural and textural attributes along with the considerable reduction in aflatoxin content.

Effect of gaseous ozone treatment on biofilm of dairy-isolated Pseudomonas spp. strains.

Microbial biofilms existing in food industries have been implicated as important contamination sources of spoilage and pathogenic microorganisms in the finished products. Among the innovative strategies proposed to contrast biofilms in food environments, ozone is recognised as an environmentally friendly technology but there are few studies about its effect against bacterial biofilms. The objective of this study was to evaluate the effect of gaseous ozone (50 ppm for 6 h) in inhibition and eradication of biofilm formed by twenty-one dairyisolated Pseudomonas spp. strains. Before ozone treatments, all isolates were screened for biofilm formation according to a previously described method. Strains were then divided in four groups: weak, weak/moderate, moderate/strong, and strong biofilm producers based on the biofilm biomass value of each isolate determined using the optical density (OD - 595 nm). Inhibition treatment was effective on the strain (C1) belonging to the weak producers’ group, on all strains classified as weak/moderate producers, on two strains (C8 and C12) belonging to the group of moderate/strong producers and on one strain (C13) classified as strong producer. Conversely, eradication treatments were ineffective on all strains tested, except for the strain C4 which reduced its biofilm-forming abilities after exposure to ozone gas. In conclusion, gaseous ozone may be used to enhance existing sanitation protocols in food processing environments, but its application alone not seems sufficient to contrast Pseudomonas spp. established biofilms.

Improving carbon nanotube/copper film composite electrical performances by tailoring oxygen interface through gaseous ozone treatment of carbon nanotube films

We experimentally establish for the first time the influence of oxygen at carbon nanotube (CNT)-Cu interface on CNT/Cu composite electrical performances. We fabricated CNT/Cu films (CCF) with systematically varied oxygen interface characteristics through Cu electron beam deposition of CNT films functionalized by O3(g) exposure. By altering O3(g) exposure times (30–1000 s), different contents and types of interfacial O-functionalities (sp3C-O and sp2CO) were obtained. CCF with optimal interfacial oxygen type and content showed enhanced CNT-Cu wetting and improvement in 4-probe electrical conductivities and their temperature stability. For e.g., Cu/CNT with interface sp3C-O and sp2CO and O:C at% ratio ~4.6 × 10–1 showed 1.6 × and 1.8 × higher electrical conductivity at room temperature and 110 °C, respectively than composites with only sp3C-O interface and O:C at% ratio ~2.7 × 10–1. Favorable effects of interfacial oxygen in previous literature have chiefly focused on CNT/Cu mechanical performances. Systematic studies on electrical performances vs. interfacial oxygen content and type are absent. Our results fill this knowledge-gap and provide experimental evidence on benefits of optimally tailored interfacial oxygen functionalities for enhancing Cu-nanotube interactions and composite electrical performances. We believe our work will add to existing CNT/Cu interface tailoring toolkits in literature, aiding fabrication and application-development of lightweight composites with rivaling performances.