Advanced oxidation process for the inactivation of Salmonella typhimurium on tomatoes by combination of gaseous ozone and aerosolized hydrogen peroxide

Antimicrobial Activity of Hydrogen Peroxide for Application in Food Safety and COVID-19 Mitigation: An Updated Review

Hydrogen peroxide (H2O2) is a well-known agent with a broad-spectrum antimicrobial activity against pathogenic bacteria, fungi, and viruses. It is a colorless liquid and commercially available in aqueous solution over a wide concentration range. It has been extensively used in the food industry by virtue of its strong oxidizing property and its ability to cause cellular oxidative damage in microbial cells. This review comprehensively documents recent research on the antimicrobial activity of H2O2 against organisms of concern for the food industry, as well as its effect against SARS-CoV-2 responsible for the COVID-19 pandemic. In addition, factors affecting the antimicrobial effectiveness of H2O2, different applications of H2O2 as a sanitizer or disinfectant in the food industry as well as safety concerns associated with H2O2 are discussed. Finally, recent efforts in enhancing the antimicrobial efficacy of H2O2 are also outlined.

CodY: An Essential Transcriptional Regulator Involved in Environmental Stress Tolerance in Foodborne Staphylococcus aureus RMSA24

Staphylococcus aureus (S. aureus), as the main pathogen in milk and dairy products, usually causes intoxication with vomiting and various kinds of inflammation after entering the human body. CodY, an important transcriptional regulator in S. aureus, plays an important role in regulating metabolism, growth, and virulence. However, little is known about the role of CodY on environmental stress tolerance. In this research, we revealed the role of CodY in environmental stress tolerance in foodborne S. aureus RMSA24. codY mutation significantly reduced the tolerance of S. aureus to desiccation and oxidative, salt, and high-temperature stresses. However, S. aureus was more tolerant to low temperature stress due to mutation of codY. We found that the expressions of two important heat shock proteins-GroEL and DanJ-were significantly down-regulated in the mutant codY. This suggests that CodY may indirectly regulate the high- and low-temperature tolerance of S. aureus by regulating the expressions of groEL and danJ. This study reveals a new mechanism of environmental stress tolerance in S. aureus and provides new insights into controlling the contamination and harm caused by S. aureus in the food industry.

Ozone based inactivation and disinfection in the pandemic time and beyond: Taking forward what has been learned and best practice

The large-scale global COVID-19 has a profound impact on human society. Timely and effectively blocking the virus spread is the key to controlling the pandemic growth. Ozone-based inactivation and disinfection techniques have been shown to effectively kill SARS-CoV-2 in water, aerosols and on solid surface. However, the lack of an unified information and discussion on ozone-based inactivation and disinfection in current and previous pandemics and the absence of consensus on the main mechanisms by which ozone-based inactivation of pandemic causing viruses have hindered the possibility of establishing a common basis for identifying best practices in the utilization of ozone technology. This article reviews the research status of ozone (O3) disinfection on pandemic viruses (especially SARS-CoV-2). Taking sterilization kinetics as the starting point while followed by distinguishing the pandemic viruses by enveloped and non-enveloped viruses, this review focuses on analyzing the scope of application of the sterilization model and the influencing factors from the experimental studies and data induction. It is expected that the review could provide an useful reference for the safe and effective O3 utilization of SARS-CoV-2 inactivation in the post-pandemic era.

A novel gdmH-related gene, ghl, involved in environmental stress tolerance and vancomycin susceptibility in milk-derived Staphylococcus aureus

Staphylococcus aureus is one of the main microorganisms that contaminate dairy products and pickled foods, and has a great impact on economy and human health. GdmH-related proteins, as important functional units widely present in Staphylococcus species, have not been reported in S. aureus so far. In this study, we identified a gdmH-related gene, named ghl. We found that mutation of ghl gene could decrease the tolerance of environmental stresses (heat, desiccation, salt and hydrogen peroxide) of S. aureus and enhanced the capacities of biofilm formation. In addition, the ghl mutant was more sensitive to vancomycin on CAMHB solid plates but more resistant to vancomycin in CAMHB liquid medium compared to wild type RMSA24. These results indicated that ghl is an important factor to respond to environmental stress in foodborne S. aureus. This paper for the first time reported that a GdmH-related protein plays an important role in environmental tolerance, providing a new direction for the follow-up study of GdmH-related proteins, as well as a potential target gene for further research on the tolerance mechanism of Staphylococcus aureus in food processing and the control of biofilm formation.

Ozone Treatments for Preserving Fresh Vegetables Quality: A Critical Review

Ozone is recognized as an antimicrobial agent for vegetables storage, washing, and processing. This strong disinfectant is now being used in the food industry. In this review, the chemical and physical properties of ozone, its generation, and factors affecting ozone processing efficiency were explained as well as recent regulatory developments in the food industry. By then selecting three vegetables, we show that ozone avoids and controls biological growth on vegetables, keeping their attractive appearance and sensorial qualities, assuring nutritional characteristics' retention and maintaining and increasing the shelf-life. In liquid solution, ozone can be used to disinfect processing water and vegetables, and in gaseous form, ozone helps to sanitize and preserve vegetables during storage. The multifunctionality of ozone makes it a promising food processing agent. However, if ozone is improperly used, it causes some deleterious effects on products, such as losses in their sensory quality. For an effective and a safe use of ozone, specific treatment conditions should be determined for all kinds of vegetables. In a last step, we propose highlighting the different essential characteristics of ozone treatment in order to internationally harmonize the data relating to the treatments carried-out.

Advanced Oxidation Process as a Postharvest Decontamination Technology To Improve Microbial Safety of Fresh Produce

Fresh produce is frequently associated with outbreaks of foodborne diseases; thus, there is a need to develop effective intervention technologies and antimicrobial treatments to improve the microbial safety of fresh produce. Washing with chemical sanitizers, commonly used by the industry, is limited in its effectiveness and is viewed as a possible cross-contamination opportunity. This review discuses the advanced oxidation process (AOP), which involves generating highly reactive hydroxyl radicals to inactivate human pathogens. Ionizing irradiation, ultraviolet (UV) light, and cold plasma can be regarded as AOP; however, AOPs employing combinations of UV, H₂O₂, cold plasma, and ozone may be more promising because higher amounts of hydroxyl radicals are produced in comparison to the individual treatments and the combinative AOPs may be more consumer friendly than ionizing irradiation. When applied as a gaseous/aerosolized treatment, AOPs may have advantages over immersion treatments, considering the reactivity of hydroxyl radicals and presence of organic materials in wash water. Gaseous/aerosolized AOPs achieve up to 5 log reductions of pathogenic bacteria on fresh produce compared to reductions of 1-2 logs with aqueous sanitizers. Further research needs to be conducted on specific AOPs before being considered for commercialization, such as reduced formation of undesirable chemical byproducts, impact on quality, and scaled up studies.