Modeling the inactivation of Bacillus subtilis spores during cold plasma sterilization

Cold plasma: Unveiling its impact on hydration, rheology, nutritional, and anti-nutritional properties in food materials - An overview

Non-thermal technologies, primarily employed for microbial inactivation and quality preservation in foods, have seen a surge in interest, with non-thermal plasma garnering particular attention. Cold plasma exhibits promising outcomes, including enhanced germination, improved functional and rheological properties, and microorganism destruction. This has sparked increased exploration across various domains, notably in hydration and rheological properties for creating new products. This review underscores the manifold benefits of applying cold plasma to diverse food materials, such as cereal and millet flours, and gums. Notable improvements encompass enhanced functionality, modified color parameters, altered rheological properties, and reduced anti-nutritional factors. The review delves into mechanisms like starch granule fragmentation, elucidating how these processes enhance the physical and structural properties of food materials. While promising for high-quality food development, overcoming challenges in scaling up production and addressing legal issues is essential for the technology's commercialization.

Optimization of cold plasma combined treatment process and its effect on the quality of Asian sea bass (Lates calcarifer) during refrigerated storage

BACKGROUND

Cold plasma exhibits broad applicability in the realm of fish sterilization and preservation. The combination process of plasma-activated water and dielectric barrier discharge (PAW-DBD) was optimized, and its disinfection effects on bass fillets were studied.

RESULTS

The best conditions for disinfection of PAW-DBD were as follows. Bass fillets were soaked in PAW for 150 s, and then treated by DBD system at 160 kV for 180 s. The total viable count (TVC) reduced by 1.68 log CFU g-1 . On the 15th day of refrigerated storage, TVC of PAW-DBD group was 7.01 log CFU g-1 , while the PAW and DBD group exhibited a TVC of 7.02 and 7.01 log CFU g-1 on day 12; the TVC of the control group was 7.13 log CFU g-1 on day 6. The sensory score, water-holding capacity, and 2-thiobarbituric acid reactive substance values of the PAW-DBD group were significantly higher than those of PAW and DBD group (P < 0.05), whereas the TVC, Pseudomonas spp. count, and pH of the group were significantly lower (P < 0.05) during refrigerated storage.

CONCLUSION

PAW-DBD treatment can enhance the disinfection effect, maintain good quality, and extend the storage period of bass fillets. © 2023 Society of Chemical Industry.

Non-Thermal Plasma Application in Medicine-Focus on Reactive Species Involvement

Non-thermal plasma (NTP) application in medicine is a dynamically developing interdisciplinary field. Despite the fact that basics of the plasma phenomenon have been known since the 19th century, growing scientific attention has been paid in recent years to the use of plasma in medicine. Three most important plasma-based effects are pivotal for medical applications: (i) inactivation of a broad spectrum of microorganisms, (ii) stimulation of cell proliferation and angiogenesis with lower plasma treatment intensity, and (iii) inactivation of cells by initialization of cell death with higher plasma intensity. In this review, we explain the underlying chemical processes and reactive species involvement during NTP in human (or animal) tissues, as well as in bacteria inactivation, which leads to sterilization and indirectly supports wound healing. In addition, plasma-mediated modifications of medical surfaces, such as surgical instruments or implants, are described. This review focuses on the existing knowledge on NTP-based in vitro and in vivo studies and highlights potential opportunities for the development of novel therapeutic methods. A full understanding of the NTP mechanisms of action is urgently needed for the further development of modern plasma-based medicine.

Advances of non-thermal plasma discharge technology in degrading recalcitrant wastewater pollutants. A comprehensive review

With development and urbanization, the amount of wastewater generated due to human activities drastically increases yearly, causing water pollution and intensifying the already worsened water crisis. Although convenient, conventional wastewater treatment methods such as activated sludge, stabilization ponds, and adsorption techniques cannot fully eradicate the complex and recalcitrant contaminants leading to toxic byproducts generation. Recent advancements in wastewater treatment techniques, specifically non-thermal plasma technology, have been extensively investigated for the degradation of complex pollutants in wastewater. Non-thermal plasma is an effective alternative for degrading and augmenting the biodegradability of recalcitrant pollutants due to its ability to generate reactive species in situ. This article critically reviews the non-thermal plasma technology, considering the plasma discharge configuration and reactor types. Furthermore, the influence of operational parameters on the efficiency of the plasma systems and the reactive species generated by the system during discharge has gained significant interest and hence been discussed. Also, the application of non-thermal plasma technology for the degradation of pharmaceuticals, pesticides, and dyes and the inactivation of microbial activities are outlined in this review article. Additionally, optimistic applications involving the combination of non-thermal plasma and catalysts and pilot and industrial-scale projects utilizing non-thermal plasma technology have been addressed. Concluding perceptions on the challenges and future perspectives of the non-thermal technology on wastewater treatment are accentuated. Overall, this review outlines a comprehensive understanding of the non-thermal plasma technology for recalcitrant pollutant degradation from a scientific perspective providing detailed instances for reference.

Modelling of Nonthermal Dielectric Barrier Discharge Plasma at Atmospheric Pressure and Role of Produced Reactive Species in Surface Polymer Microbial Purification

A nonthermal atmospheric plasma reactor was used to sterilize polymer surfaces and satisfy safety constraints in a biological medium. A 1D fluid model was developed using COMSOL Multiphysics software^® 5.4 with a helium-oxygen mixture at low temperature for the decontamination of bacteria on polymer surfaces. An analysis of the evolution of the homogeneous dielectric barrier discharge (DBD) was carried out through studying the dynamic behavior of the discharge parameters including the discharge current, the consumed power, the gas gap voltage, and transport charges. In addition, the electrical characteristics of a homogeneous DBD under different operating conditions were studied. The results shown that increasing voltage or frequency caused higher ionization levels and maximum increase of metastable species' density and expanded the sterilization area. On the other hand, it was possible to operate plasma discharges at a low voltage and a high density of plasma using higher values of the secondary emission coefficient or permittivity of the dielectric barrier materials. When the discharge gas pressure increased, the current discharges declined, which indicated a lower sterilization efficiency under high pressure. A short gap width and the admixture of oxygen were needed for sufficient bio-decontamination. Plasma-based pollutant degradation devices could therefore benefit from these results.

Food preservation by cold plasma from dielectric barrier discharges in agri-food industries

BACKGROUND

Cold plasma (CP) can be defined as partially or wholly ionized gas carrying myriads of highly reactive products, such as electrons, negative ions, positive ions, free radicals, excited or non-excited atoms, and photons at ambient temperature. It is generated at 30-60°C under atmospheric or reduced pressure (vacuum). In contrast to thermal plasma, it requires less power, exhibits electron temperatures much higher than the corresponding gas (macroscopic temperature), and does not present a local thermodynamic equilibrium. Dielectric barrier discharges (DBD) are one of the most convenient and efficient methods to produce CP.

SCOPE AND APPROACH

Cold plasma technology has the potential to replace traditional agri-food processing purification methods because of its low energy requirements and flexible system design. CP technology works by reducing bacteria levels and removing pests and mycotoxins from your produce at harvest. It can also catalyze physiological and biochemical reactions and modify materials. It can meet microbial food safety standards, improve the physical, nutritional, and sensory characteristics of the products, preserve unstable bioactive compounds, and modulate enzyme activities. This manuscript also discusses the quality characteristics of food components before/after CP treatment.

KEY FINDINGS AND CONCLUSION

In the past decade, CP treatments of food products have experienced increased popularity due to their potential contributions to non-thermal food processing. There is no doubt that CP treatment is a flexible approach with demonstrated efficacy for controlling many risks across food and agricultural sustainability sectors. In addition, CP technologies also can be applied in food-related areas, including modification of chemical structures and desensitization treatments. There is a need to fully assess the benefits and risks of stand-alone CP unit processes or their integration as a processing chain as soon as the economic, ecological, and consumer benefits and acceptability are considered.

Evaluation of the Role of Probiotics As a New Strategy to Eliminate Microbial Toxins: a Review

Probiotics are living microorganisms that have favorable effects on human and animal health. The most usual types of microorganisms recruited as probiotics are lactic acid bacteria (LAB) and bifidobacteria. To date, numerous utilizations of probiotics have been reported. In this paper, it is suggested that probiotic bacteria can be recruited to remove and degrade different types of toxins such as mycotoxins and algal toxins that damage host tissues and the immune system causing local and systemic infections. These microorganisms can remove toxins by disrupting, changing the permeability of the plasma membrane, producing metabolites, inhibiting the protein translation, hindering the binding to GTP binding proteins to GM1 receptors, or by preventing the interaction between toxins and adhesions. Here, we intend to review the mechanisms that probiotic bacteria use to eliminate and degrade microbial toxins.

Inactivation of Bacteria Using Bioactive Nanoparticles and Alternating Magnetic Fields

Foodborne pathogens are frequently associated with risks and outbreaks of many diseases; therefore, food safety and processing remain a priority to control and minimize these risks. In this work, nisin-loaded magnetic nanoparticles were used and activated by alternating 10 and 125 mT (peak to peak) magnetic fields (AMFs) for biocontrol of bacteria Listeria innocua, a suitable model to study the inactivation of common foodborne pathogen L. monocytogenes. It was shown that L. innocua features high resistance to nisin-based bioactive nanoparticles, however, application of AMFs (15 and 30 min exposure) significantly potentiates the treatment resulting in considerable log reduction of viable cells. The morphological changes and the resulting cellular damage, which was induced by the synergistic treatment, was confirmed using scanning electron microscopy. The thermal effects were also estimated in the study. The results are useful for the development of new methods for treatment of the drug-resistant foodborne pathogens to minimize the risks of invasive infections. The proposed methodology is a contactless alternative to the currently established pulsed-electric field-based treatment in food processing.

Bacillus spores: a review of their properties and inactivation processing technologies

Many factors determine the resistance properties of a Bacillus spore to heat, chemical and physical processing, including thick proteinaceous coats, peptidoglycan cortex and low water content, high levels of dipicolinic acid (DPA), and divalent cations in the spore core. Recently, attention has been focused on non-thermal inactivation methods based on high pressure, ultrasonic, high voltage electric fields and cold plasmas for inactivating Bacillus spores associated with deterioration in quality and safety. The important chemical sporicides are glutaraldehyde, chorine-releasing agents, peroxygens, and ethylene oxide. Some food-grade antimicrobial agents exhibit sporostatic and sporicidal activities, such as protamine, polylysine, sodium lactate, essential oils. Surfactants with hydrophilic and hydrophobic properties have been reported to have inactivation activity against spores. The combined treatment of physical and chemical treatment such as heating, UHP (ultra high pressure), PEF (pulsed electric field), UV (ultraviolet), IPL (intense pulsed light) and natural antimicrobial agents can act synergistically and effectively to kill Bacillus spores in the food industry.