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Posted in Antimicrobials, Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Technology, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Norovirus, Research, Technology, UV Microbiology
A study was conducted to evaluate a new organic produce wash composed of a combination of organic acids and hydrogen peroxide, in the form of a mixed peroxyacid solution, against foodborne pathogens. The mixed peroxyacid, composed of lactic acid, hydrogen peroxide and one or more fruit acids, was challenged against Salmonella enterica, E. coli O157:H7, or Listeria monocytogenes in suspension or on the surface of dip-inoculated cherry tomatoes. Cherry tomatoes were also treated with 8 ppm of free chlorine added in the form of sodium hypochlorite (NaOCL). When tested against planktonic cells in pure culture for 120 s, Salmonella, and E. coli O157:H7 were reduced by 7.5 and 7.1 log cycles with 0.40% of the peroxyacid solution, respectively, while L. monocytogenes decreased by 5.0 log by treatment with a 0.80% solution. When cherry tomatoes were dip-inoculated and treated with 8 ppm free chlorine, Salmonella and E. coli O157:H7 populations decreased by 2.5 and 2.6 log, respectively, which were not significantly different than reductions incurred by sterile water rinses. A 1.0% solution of peroxyacid solution, however, reduced the same microorganisms by 3.8 and 3.4 log per tomato, respectively, which was significantly greater ( P < 0.05) than reductions achieved by the 2 min sterile water rinse. When dip-inoculated with L. monocytogenes, and treated, populations were reduced by 3.5 log per tomato with 1.0% peroxyacid solution which was greater ( P < 0.05) than reductions achieved by 8 ppm free Cl (2.6 log) or sterile water (1.7 log). Results demonstrate that this peroxyacid combination antimicrobial wash may be an effective organic produce wash for preventing cross-contamination during the washing of cherry tomatoes, as well as being capable of inactivating up to 3.8, 3.4, and 3.5 log per tomato of S. enterica, E. coli O157:H7 and L. monocytogenes , respectively.
Posted in Decontamination Microbial, E.coli O157, E.coli O157:H7, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, Listeria, Listeria monocytogenes, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Salmonella, Technology

Oregano essential oil (OEO) is an effective natural antibacterial agent, but its antibacterial activity against Vibrio vulnificus has not been widely studied. The aim of this study was to investigate the inhibitory effect and germicidal activity of OEO on V. vulnificus and its possible inhibition mechanism. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of OEO against four V. vulnificus strains (ATCC 27562 and three isolates from seafoods) were from 0.06 to 0.15 μL/mL. Compared with untreated bacteria, OEO reduced the concentration of intracellular adenosine triphosphate (ATP), hyperpolarized the cell membrane, increased the level of reactive oxygen species (ROS), and increased the concentration of intracellular malondialdehyde (MDA), but there was no obvious DNA damage at the OEO test concentration. It was indicated that OEO inactivated V. vulnificus by generating ROS which caused lipid peroxidation of cell membranes, thereby reducing the permeability and integrity of cell membranes and causing morphological changes to cells, but there was no obvious damage to DNA. In addition, OEO could effectively kill V. vulnificus in oysters at 25 °C, and the number of bacteria decreased by 48.2% after 0.09% OEO treatment for 10 h. The good inhibitory effect and bactericidal activity of OEO showed in this study, and the economy and security of OEO make it possible to apply OEO to control V. vulnificus contamination in oysters and other seafoods. View Full-Text
Posted in Antibacterial, Antimicrobials, Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Technology, Vibrio, Vibrio vulnificans, Vibrio vulnificus
The aim of the present study was to investigate the ability of natural plant-derivate (flavonoid compounds) products to reduce and/or inhibit the biofilm-forming ability of Listeria monocytogenes. A collection of 500 synthetic and natural flavonoids were tested on strains of L. monocytogenes for their antimicrobial and anti-biofilm activity. L. monocytogenes biofilm inhibition by flavonoid compounds was tested on i) stainless steel coupons using crystal violet staining and ii) glass slides using confocal laser scanning microscopic (CLSM) imaging. The flavonoids were tested against a L. monocytogenes cocktail of 5 strains at a concentration of 100 µM to determine their effect on planktonic growth. A total of 17 flavonoids were chosen for further study due to their ability to significantly reduce the growth of L. monocytogenes in BHI broth, while 2 flavonoids were chosen because they actually increased growth. A lower concentration of flavonoid compounds (50 µM) was selected to investigate their effects on L. monocytogenes biofilm formation using i) stainless steel coupons to quantify biomass and ii) glass coupons to observe the biofilm architecture. The 19 flavonoids showed various levels of L. monocytogenes growth inhibition, ranging from 2% to 100%, as compared to the respective positive and negative controls on stainless steel, after 48 h of incubation at 22 o C. In addition, in comparison to the control, most of the 19 flavonoids significantly (p ≤ 0.05) inhibited biofilm formation, with at least one of the L. monocytogenes strains or at one of the tested temperatures. In fact, when grown in BHI broth with 50 µM of the 19 selected flavonoid compounds for 48 h at 22 o C, there were visible reductions in L. monocytogenes biofilm formation on the glass coupons. Overall, we found multiple flavonoid compounds to be promising anti-biofilm and antimicrobial agents against L. monocytogenes .
Posted in Biofilm, Decontamination Microbial, Flavanoid, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, Listeria, Listeria monocytogenes, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Technology
Posted in Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Technology, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Pathogen, pathogenic, Research, Technology
Bacillus weihenstephanensis can grow at refrigeration temperature and cause food poisoning. It has been isolated from liquid whole egg products. The moderate heat used for pasteurization of liquid egg products is ineffective for killing spore-forming bacteria including Bacillus. Available predictive models and a pretrial study in broth suggested the potential for growth of Bacillus spp. under the tested conditions. Hence, hurdles such as storage of product below 4°C or use of preservatives would be needed to ensure the food safety of pasteurized egg products. This study evaluated the growth inhibition of B. weihenstephanensis in pasteurized liquid whole egg product formulated with 6.25 ppm nisin during storage at refrigerated and abuse refrigerated temperatures for a total 13 weeks, in three replicate trials. At day 0, the product had a pH of 7.52±0.29, while background microflora such as aerobic plate counts, presumptive B. cereus, and yeast and molds were <10 CFU/g. Product inoculated with target 2.5 log10 CFU/g of B. weihenstephanensis, stored at 4°C for 4 weeks and subsequently at 7 or 10°C for 9 weeks exhibited no growth in all three replicate trials. Average counts reduced (p<0.05) by at least one-log10 in six weeks in all samples stored at either 7 or 10°C. Similarly, growth of total plate counts, presumptive Bacillus spp., yeast and mold counts was not observed in uninoculated controls stored at 4°C for 4 weeks and subsequently at 7 or 10°C for 9 weeks. Visual and odor evaluation performed at each sampling time point showed no abnormalities. This study assessed the efficacy of maximum allowed level of nisin for use in pasteurized liquid whole eggs and validated the inhibition of B. weihenstephanensis in the product for an extended shelf life of up to 13 weeks.
Posted in Bacillus, Bacillus weihenstephanensis, Decontamination Microbial, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Technology

Food packaging with efficient antibacterial ability is highly desirable and challenging in facing the crisis of microbial contamination. However, most present packaging is based on metal-based antibacterial agents and requires a time-consuming antibacterial process. Here, the unique packaging (CC/BB films) featuring aggregation-induced emission behavior and photodynamic inactivation activity is prepared by dispersing self-assembled berberine–baicalin nanoparticles (BB NPs) into a mixed matrix of sodium carboxymethylcellulose-carrageenan (CC). The superiority of this design is that this packaging film can utilize sunlight to generate reactive oxygen species, thus eradicating more than 99% of E. coli and S. aureus within 60 min. Also, this film can release BB NPs to inactivate bacteria under all weather conditions. Surprisingly, the CC/BB nanocomposite film presented excellent mechanical performances (29.80 MPa and 38.65%), hydrophobicity (117.8°), and thermostability. The nanocomposite film is validated to be biocompatible and effective in protecting chicken samples, so this work will provide novel insights to explore safe and efficient antibacterial food packaging.
Posted in Decontamination Microbial, E.coli, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Staphylococcus aureus, Technology
Researchers at the University of California-Davis have developed a new type of cooling cube with the potential, they say, to transform how cold storage is done.
The benefits of plastic-free, “jelly ice cubes” are that they do not melt, are compostable and antimicrobial, and can help prevent cross-contamination.
It can be easy for foodservice operators and their employees not to think about the food safety implications of how ice is used and handled. If they don’t take proper precautionary measures to handle food properly or keep up with necessary preventive maintenance measures to ensure that their ice machines are clean, sanitary and operating safely, there can be serious food safety risks. The researchers at the UC-Davis took note of this concern.
The researchers began working on their coolant cubes after Luxin Wang, an associate professor in the Department of Food Science and Technology, saw the amount of ice used at fish-processing plants and the cross-contamination that meltwater could spread among products or drains.
“The amount of ice used by these fish-processing sites is massive,” Wang said. “We need to control the pathogens.”
Posted in Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Safety, Food Technology, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Research, Technology
Background: Disinfection of medical devices designed for clinical use associated or not with the growing area of tissue engineering is an urgent need. However, traditional disinfection methods are not always suitable for some biomaterials, especially those sensitive to chemical, thermal, or radiation. Therefore, the objective of this study was to evaluate the minimal concentration of ozone gas (O3) necessary to control and kill a set of sensitive or multi-resistant Gram-positive and Gram-negative bacteria. The cell viability, membrane permeability, and the levels of reactive intracellular oxygen (ROS) species were also investigated;
Material and Methods: Four standard strains and a clinical MDR strain were exposed to low doses of ozone at different concentrations and times. Bacterial inactivation (cultivability, membrane damage) was investigated using colony counts, resazurin as a metabolic indicator, and propidium iodide (PI). A fluorescent probe (H2DCFDA) was used for the ROS analyses;
Results: No reduction in the count colony was detected after O3 exposure compared to the control group. However, the cell viability of E. coli (30%), P. aeruginosa (25%), and A. baumannii (15%) was reduced considerably. The bacterial membrane of all strains was not affected by O3 but presented a significant increase of ROS in E. coli (90 ± 14%), P. aeruginosa (62.5 ± 19%), and A. baumanni (52.6 ± 5%);
Conclusion: Low doses of ozone were able to interfere in the cell viability of most strains studied, and although it does not cause damage to the bacterial membrane, increased levels of reactive ROS are responsible for causing a detrimental effect in the lipids, proteins, and DNA metabolism. View Full-Text
Posted in Decontamination Microbial, E.coli, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Technology, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Ozone, Pathogen, pathogenic, Pseudomonas, Pseudomonas aeruginosa, Pseudomonas fluorescens, Research, Technology
Inhibiting the growth of spoilage bacteria, such as Pseudomonas spp., is key to reducing spoilage in fish. The mucus adhesion test in vitro showed that the adhesion ability of Bacillus subtilis was positively correlated with its inhibition ability to Pseudomonas spp. In vivo experiments of tilapia showed that dietary supplementation with B. subtilis could reduce the adhesion and colonization of Pseudomonas spp. in fish intestines and flesh, as well as reduce total volatile basic nitrogen (TVB-N) production. High throughput and metabolomic analysis showed treatment with B. subtilis, especially C6, reduced the growth of Pseudomonas spp., Aeromonas spp., Fusobacterium spp., and Enterobacterium spp., as well as aromatic spoilage compounds associated with these bacteria, such as indole, 2,4-bis(1,1-dimethylethyl)-phenol, 3-methyl-1-butanol, phenol, and 1-octen-3-ol. Our work showed that B. subtilis could improve the flavor of fish by changing the intestinal flora of fish, and it shows great promise as a microecological preservative. View Full-Text
Posted in Bacillus, Bacillus Subtilis, Decontamination Microbial, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiological Risk Assessment, Microbiology, Microbiology Investigations, Pseudomonas, Pseudomonas aeruginosa, Research, Technology