Evaluation of Selected Properties of Dielectric Barrier Discharge Plasma Jet.

In the technological processes requiring mild treatment, such as soft materials processing or medical applications, an important role is played by non-equilibrium plasma reactors with dielectric barrier discharge (DBD), that when generated in noble gases allows for the effective treatment of biological material at a low temperature. The aim of this study is to determine the operating parameters of an atmospheric pressure, radio-frequency DBD plasma jet reactor for the precise treatment of biological materials. The tested parameters were the shape of the discharge (its length and volume), current and voltage signals, as well as the power consumed by the reactor for various composition and flow rates of the working gas. To determine the applicability in medicine, the temperature, pH, concentrations of H2O2, NO2- and NO3- and Escherichia coli log reduction in the plasma treated liquids were determined. The obtained results show that for certain operating parameters, a narrow shape of plasma stream can generate significant amounts of H2O2, allowing for the mild decontamination of bacteria at a relatively low power of the system, safe for the treatment of biological materials.

Pilot study on the use of cold atmospheric plasma for preservation of bread.

Cold atmospheric plasma (CAP) is used as an emerging technology for food preservation. In this study, CAP treatment has been applied to bakery products for the first time. The aim of the work was to investigate the effect of the use of CAP on the amount of microorganisms during bread storage. Basic physicochemical properties and bread texture were determined during storage for 0, 3, and 6 days. The study material included gluten-free and mixed wheat-rye bread treated with CAP for 2 and 10 min. The results showed that no mesophilic bacteria or fungi were found after ten minutes of the bread exposure to CAP. In addition, only 2-min non-thermal sterilization resulted in complete inhibition of yeast and mould growth in the gluten-free and wheat-rye bread. A decrease in the microbial growth in the bread was noted; however, a simultaneous decrease in the moisture content of the bread was observed. After the application of plasma for 2 or 10 min, both the gluten-free and mixed wheat-rye bread was characterized by reduced humidity, which also resulted in a significant increase in the hardness and a slight increase in the springiness of the bread. The use of CAP in storage of bread is promising; nevertheless, it is necessary to further study the effect of this treatment in bread with improvers, especially with hydrocolloids and fibers.

Influence of ultrasound on selected microorganisms, chemical and structural changes in fresh tomato juice.

The paper presents the possibility of applying ultrasonic technology for inactivation of mesophilic aerobic microorganisms, lactic acid bacteria, coliform bacteria, and yeast with the maintenance of the chemical and structural properties of tomato juice. The research was conducted on fresh tomato juice obtained from the Apis F1 variety. Pressed juice was exposed to high power ultrasound and frequency 20 kHz with three operational parameters: ultrasound intensity (28 and 40 W cm-2), treatment time (2, 5, and 10 min), and product storage time (1, 4, 7 and 10 days). The temperature of the juice during the sonication ranged from 37 to 52 °C depending on the intensity of ultrasound and time of treatment. Effectiveness of the tested microorganisms eradication in the juice depended on the amplitude and duration of the ultrasound treatment. It was shown that the juice exposed to an ultrasonic field with an intensity of 40 W cm-2 for 10 min was microbiologically pure and free from spoilage microorganism even after 10 storage days. No statistically significant differences in pH were found between the untreated juice and the sonicated samples. The ultrasonic treatment was found to change the content of lycopene in small degree (both an increase and a decrease, depending on the processing time) and to induce a small decrease in the vitamin C content. The study suggests that the ultrasonic treatment can be successfully implemented on an industrial scale for the production of not-from-concentrate (NFC) tomato juice.

Possibility to extend the shelf life of NFC tomato juice using cold atmospheric pressure plasma.

Cold Atmospheric pressure Plasma (CAP) is a non-thermal method used in food processing. CAP generated with the use of nitrogen in a Glide-arc device for 300 to 600 s exhibited high potential for microbial decontamination and did not induce substantial changes in the physicochemical properties of NFC tomato juice. Samples exposed to cold atmospheric plasma had mostly an intact structure, as revealed by digital microscopy. The investigations indicate that CAP can be applied for biological and chemical waste-free decontamination of food and extension of its shelf life.

Positive Effect of Cold Atmospheric Nitrogen Plasma on the Behavior of Mesenchymal Stem Cells Cultured on a Bone Scaffold Containing Iron Oxide-Loaded Silica Nanoparticles Catalyst.

Low-temperature atmospheric pressure plasma was demonstrated to have an ability to generate different reactive oxygen and nitrogen species (RONS), showing wide biological actions. Within this study, mesoporous silica nanoparticles (NPs) and FexOy/NPs catalysts were produced and embedded in the polysaccharide matrix of chitosan/curdlan/hydroxyapatite biomaterial. Then, basic physicochemical and structural characterization of the NPs and biomaterials was performed. The primary aim of this work was to evaluate the impact of the combined action of cold nitrogen plasma and the materials produced on proliferation and osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells (ADSCs), which were seeded onto the bone scaffolds containing NPs or FexOy/NPs catalysts. Incorporation of catalysts into the structure of the biomaterial was expected to enhance the formation of plasma-induced RONS, thereby improving stem cell behavior. The results obtained clearly demonstrated that short-time (16s) exposure of ADSCs to nitrogen plasma accelerated proliferation of cells grown on the biomaterial containing FexOy/NPs catalysts and increased osteocalcin production by the cells cultured on the scaffold containing pure NPs. Plasma activation of FexOy/NPs-loaded biomaterial resulted in the formation of appropriate amounts of oxygen-based reactive species that had positive impact on stem cell proliferation and at the same time did not negatively affect their osteogenic differentiation. Therefore, plasma-activated FexOy/NPs-loaded biomaterial is characterized by improved biocompatibility and has great clinical potential to be used in regenerative medicine applications to improve bone healing process.

Evaluation of selected microbial and physicochemical parameters of fresh tomato juice after cold atmospheric pressure plasma treatment during refrigerated storage.

The Cold Atmospheric pressure Plasma (CAP) technology is an emerging technology used for conditioning and microbiological decontamination of biomaterials including food. A novel tool for inactivation of juice background spoilage microorganisms, as well as high count of inoculated yeast while maintaining physicochemical properties in tomato juice - CAP technology was utilized in this study. Dry matter content and pH were not significantly influenced by CAP generated in GlidArc reactor. Small increase of lycopene, and slight loss of vitamin C content were observed.

Effects of atmospheric pressure plasma jet operating with DBD on Lavatera thuringiaca L. seeds' germination.

The paper presents the results of an experiment on the effect of pre-sowing stimulation of seeds with atmospheric pressure plasma jet operating with dielectric barrier discharge (DBD plasma jet) on the process of germination of Thuringian Mallow (Lavatera thuringiaca L.). Five groups of seeds characterized by a different exposure times (1, 2, 5, 10 and 15 minutes) as well as untreated seeds-control were used. Pre-sowing plasma stimulation of seeds improved germination parameters such as: germination capacity and germination energy for all tested groups relative to control. The highest germination parameters were obtained for seeds stimulated with plasma for the exposure times of 2 and 5 min. The analysis of the contact surface angle indicated the decrease of its' mean values upon seed stimulation while no statistical effects were observed. Analysis of the SEM scans revealed the increase in seed pattern intensity which could be attributed to removing of the surface parts of cuticle possibly covered with wax upon short time-2 and 5 min plasma treatment. Such a phenomenon can act similarly to mechanical scarification of seeds. Longer exposure of seeds to plasma resulted in affecting the deeper zone of cuticle and damage or fracture of some parts of the cuticle. Lower germination parameters of seeds upon longer exposure times to plasma may indicate mechanical damage of the seeds.