Category Archives: UV Microbiology

Research – UV-C LED Irradiation Reduces Salmonella on Chicken and Food Contact Surfaces

Posted on June 24, 2021 by | Leave a comment

MDPI

Ultraviolet (UV-C) light-emitting diode (LED) light at a wavelength of 250–280 nm was used to disinfect skinless chicken breast (CB), stainless steel (SS) and high-density polyethylene (HD) inoculated with Salmonella enterica. Irradiances of 2 mW/cm2 (50%) or 4 mW/cm2 (100%) were used to treat samples at different exposure times. Chicken samples had the lowest Salmonella reduction with 1.02 and 1.78 Log CFU/cm2 (p ≤ 0.05) after 60 and 900 s, respectively at 50% irradiance. Higher reductions on CB were obtained with 100% illumination after 900 s (>3.0 Log CFU/cm2). Salmonella on SS was reduced by 1.97 and 3.48 Log CFU/cm2 after 60 s of treatment with 50% and 100% irradiance, respectively. HD showed a lower decrease of Salmonella, but still statistically significant (p ≤ 0.05), with 1.25 and 1.77 Log CFU/cm2 destruction for 50 and 100% irradiance after 60 s, respectively. Longer exposure times of HD to UV-C yielded up to 99.999% (5.0 Log CFU/cm2) reduction of Salmonella with both irradiance levels. While UV-C LED treatment was found effective to control Salmonella on chicken and food contact surfaces, we propose three mechanisms contributing to reduced efficacy of disinfection: bacterial aggregation, harboring in food and work surface pores and light absorption by fluids associated with CB. View Full-Text

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiological Risk Assessment, Microbiology, Research, Salmonella, Salmonella in Chicken, UV Microbiology

Research – Norovirus Resistance

Posted on April 24, 2021 by | Leave a comment

Outbreak News Today

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Clusters of a virus known to cause stomach flu are resistant to detergent and ultraviolet disinfection, according to new research co-led by Danmeng Shuai, Ph.D., an associate professor of civil and environmental engineering at the George Washington University and Nihal Altan-Bonnet, Ph.D., a senior investigator and the head of the Laboratory of Host-Pathogen Dynamics at the National Heart, Lung, and Blood Institute, part of the National Institutes of Health. The findings suggest the need to revisit current disinfection, sanitation and hygiene practices aimed at protecting people from noroviruses.

Noroviruses are the leading cause of gastroenteritis around the world, with over 21 million cases each year in the United States alone.

In 2018, Altan-Bonnet’s team found that noroviruses can be transmitted to humans via membrane-enclosed packets that contain more than one virus. In the past, scientists thought that viruses spread through exposure to individual virus particles, but the 2018 study–and others–showed how membrane-enclosed clusters arrive at a human cell and release an army of viruses all at once.

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Posted in Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Virus, microbial contamination, Norovirus, Research, UV Microbiology

Research – Bacterial Spore Inactivation in Orange Juice and Orange Peel by Ultraviolet-C Light

Posted on April 15, 2021 by | Leave a comment

MDPI

Spore-forming bacteria are a great concern for fruit juice processors as they can resist the thermal pasteurization and the high hydrostatic pressure treatments that fruit juices receive during their processing, thus reducing their microbiological quality and safety. In this context, our objective was to evaluate the efficacy of Ultraviolet-C (UV-C) light at 254 nm on reducing bacterial spores of Alicyclobacillus acidoterrestris, Bacillus coagulans and Bacillus cereus at two stages of orange juice production. To simulate fruit disinfection before processing, the orange peel was artificially inoculated with each of the bacterial spores and submitted to UV-C light (97.8–100.1 W/m2) with treatment times between 3 s and 10 min. The obtained product, the orange juice, was also tested by exposing the artificially inoculated juice to UV-C light (100.9–107.9 W/m2) between 5 and 60 min. A three-minute treatment (18.0 kJ/m2) reduced spore numbers on orange peel around 2 log units, while more than 45 min (278.8 kJ/m2) were needed to achieve the same reduction in orange juice for all evaluated bacterial spores. As raw fruits are the main source of bacterial spores in fruit juices, reducing bacterial spores on fruit peels could help fruit juice processors to enhance the microbiological quality and safety of fruit juices. View Full-Text

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Posted in Alicyclobacillus, Bacillus, Bacillus cereus, Bacillus coagulans, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, microbial contamination, Microbiology, Research, UV Microbiology

Research – UVC and Foodborne Pathogens

Posted on November 15, 2020 by | Leave a comment

Recently Heard

It really works when UVC runs. When used properly, it can kill up to 99 percent of pathogens. This is why UVC treatment has been used for sterilizing equipment in clinical and laboratory settings for many years. It’s only in the last few years that UVC has started to take off for personal use, especially given the current COVID-19 pandemic.

But in various contexts, there are a lot of legitimate questions and concerns about the safety of using UVC disinfection. And so rightfully. UVC is an exceptionally strong form of ultraviolet radiation that, when not used correctly, can be dangerous to humans. We are almost never exposed to these high-frequency light waves because almost all the UVC emitted by the sun is blocked by the atmosphere. However, in mere minutes, exposure to artificial UVC light can cause sunburn.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Technology, microbial contamination, Microbiology, Pathogen, Research, Technology, UV Microbiology

Research – Evaluation of UVC Radiation and a UVC-Ozone Combination as Fresh Beef Interventions against Shiga Toxin–Producing Escherichia coli, Salmonella, and Listeria monocytogenes and Their Effects on Beef Quality

Posted on September 5, 2020 by | Leave a comment

JFP

ABSTRACT

This research study was conducted to evaluate treatments with UVC light and a combination of UVC and ozone that have recently received attention from the beef processing industry as antimicrobial interventions that leave no chemical residues on products. The effectiveness of UVC and UVC plus gaseous ozone treatments was evaluated for inactivation of pathogenic bacteria on fresh beef and for any impact on fresh beef quality. Fresh beef tissues were inoculated with cocktails of Shiga toxin–producing Escherichia coli (STEC) strains (serotypes O26, O45, O103, O111, O121, O145, and O157:H7), Salmonella, and Listeria monocytogenes. Inoculated fresh beef tissues were subjected to UVC or UVC-ozone treatments at 106 to 590 mJ/cm2. UVC treatment alone or in combination with ozone reduced populations of STEC, Salmonella, L. monocytogenes, and aerobic bacteria from 0.86 to 1.49, 0.76 to 1.33, 0.5 to 1.14, and 0.64 to 1.23 log CFU, respectively. Gaseous ozone alone reduced populations of E. coli O157:H7, Salmonella, and L. monocytogenes by 0.65, 0.70, and 0.33 log CFU, respectively. Decimal reduction times (D-values) for STEC serotypes, Salmonella, and L. monocytogenes on surfaces of fresh beef indicated that the UVC-ozone treatment was more effective (P ≤ 0.05) than UVC light alone for reducing pathogens on the surface of fresh beef. Exposure to UVC or UVC plus gaseous ozone did not have a deleterious effect on fresh meat color and did not accelerate the formation of oxidative rancidity. These findings suggest that UVC and UVC in combination with gaseous ozone can be useful for enhancing the microbial safety of fresh beef without impairing fresh beef quality.

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Posted in Bacteria, bacterial contamination, food contamination, Food Hygiene, Food Inspections, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Pathogen, Food Poisoning, Food Safety, Listeria monocytogenes, microbial contamination, Microbiology, Salmonella, UV Microbiology

Research -Extension of shelf life of pasteurized trim milk using ultraviolet treatment

Posted on January 25, 2020 by | Leave a comment

Wiley Online

The demand for minimally processed foods has increased in the last few years and gains high acceptability among consumers as it has better nutritional value than highly processed foods. Pasteurized milk is minimally processed and consumed largely for its fresh taste and higher nutritional value compared to ultrahigh temperature (UHT) and powdered milk. However, one of the constraints is its limited shelf life under refrigeration, as it cannot retain quality and safety for more than 14 days. Nonthermal technologies can extend the shelf life of milk while using low energy. Ultraviolet (UV‐C) is well known to inactivate spores as well as vegetative cells. In this study, it was shown that 2.64 J/ml of UV‐C treatment applied on pasteurized trim milk can extend shelf life up to 53 days under refrigeration. This finding was also supported by the inactivation of 3.40 ± 0.14 log of thermoresistant Geobacillus stearothermophilus spores (ATCC 7953) in UHT (or sterilized) trim milk with similar UV‐C operating conditions. Therefore, microbial study together with physicochemical properties demonstrated that pasteurization followed by UV‐C can enhance the shelf life of trim milk considerably.

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Posted in Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Microbiology Testing, Food Technology, Geobacillus stearothermophilus, microbial contamination, Microbiology, Research, Technology, Uncategorized, UV Microbiology

Research – Simultaneous Effects of UV-A and UV-B Irradiation on the Survival of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in Buffer Solution and Apple Juice

Posted on December 15, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

The objective of this study was to evaluate the efficacy of simultaneous UV-A and UV-B irradiation (UV-A+B) for inactivating Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in both phosphate-buffered saline (PBS) and apple juice. A cocktail of the three pathogens was inoculated into PBS and apple juice, and then the suspensions were irradiated with UV lamps of 356 nm (UV-A) and 307 nm (UV-B). Significant (P < 0.05) log reductions of the three pathogens in PBS and apple juice were observed after a maximum dose of UV-B alone or the UV-A+B treatment, but few reductions were observed upon UV-A treatment alone. At all irradiation times, antagonistic effects were observed for the application of UV-A+B against in E. coli O157:H7, Salmonella Typhimurium, and L. monocytogenes in PBS and apple juice. The degree of antagonistic effect in apple juice was greater than that in PBS. The results of this study suggest that the combined treatment of commercial UV-A and UV-B lamps would be impractical for disinfecting juice products.

HIGHLIGHTS

  • Antimicrobial effect of UV-A+B irradiation in PBS and apple juice was investigated.

  • UV-A+B irradiation was antagonistic for inactivating pathogens in the PBS and juice.

  • The degree of antagonistic effect in apple juice was greater than that in PBS.

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Posted in E.coli, E.coli O157, E.coli O157:H7, Food Micro Blog, Food Microbiology, Food Microbiology Blog, Food Microbiology Research, Food Technology, microbial contamination, Microbiology, Research, Salmonella, Technology, Uncategorized, UV Microbiology

Research – Evaluating a Combined Method of UV and Washing for Sanitizing Blueberries, Tomatoes, Strawberries, Baby Spinach, and Lettuce

Posted on November 2, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

We assessed a fresh produce decontamination system using a combined method of UV and washing (water-assisted UV [WUV]) in different scales. The system used tap water to wash fresh produce while exposing it to UV light. First, the reduction of Salmonella in tap water under UV treatment (1 to 1,740 mJ/cm2) was determined. Increasing the UV dose significantly (P < 0.05) increased the Salmonella reduction in wash water, and UV intensity of more than 2 mW/cm2 could reduce Salmonella in tap water to below 1 CFU/mL given enough processing time (more than 1 min; UV dose of 120 mJ/cm2). Then, the decontamination effectiveness of a small WUV system was tested on blueberries (50 g). Blueberries were spot or dip inoculated with a Salmonella cocktail and treated by the small WUV system (200 mL of water). In general, WUV treatments achieved significantly better Salmonella inactivation than tap water wash; tap water wash (10 min) and 2 mW/cm2 WUV treatment (with a UV dose of 1,200 mJ/cm2) reduced populations of spot-inoculated Salmonella on blueberries by 2.44 and 5.45 log, respectively. Compared with spot-inoculated Salmonella on blueberries, dip-inoculated Salmonella was more difficult to be inactivated by WUV treatments. Then, the decontamination effectiveness of WUV treatments was tested on blueberries (170 g), tomatoes (290 g), strawberries (170 g), baby spinach (60 g), and lettuce (60 g) using a larger WUV system. In general, 10 min of 29 mW/cm2 WUV treatment (a high UV dose of 17,400 mJ/cm2) resulted in significantly better Salmonella inactivation than tap water wash (for 10 min) regardless the inoculation method, agreeing with the results of the small-scale study. For both spot- and dip-inoculated lettuce, no significant difference (P > 0.05) in Salmonella inactivation by WUV treatments was observed when the quantity of lettuce increased from 50 to 100 g.

HIGHLIGHTS

  • Water-assisted UV showed ≤3 log more Salmonella inactivation than tap water wash.

  • Water-assisted UV showed the highest Salmonella reduction on blueberries and tomatoes.

  • More spot-inoculated Salmonella was killed than dip-inoculated Salmonella by up to 3 log.

  • Water-assisted UV of 17.4 J/cm2 could reduce Salmonella in water to less than 1 CFU/mL.

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Posted in Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, Food Technology, microbial contamination, Microbiology, Research, Technology, Uncategorized, UV Microbiology

Research – Sanitization of Chicken Frames by a Combination of Hydrogen Peroxide and UV Light To Reduce Contamination of Derived Edible Products

Posted on October 26, 2019 by | Leave a comment

Journal of Food Protection

ABSTRACT

Chicken carcass frames are used to obtain mechanically separated chicken (MSC) for use in other further processed food products. Previous foodborne disease outbreaks involving Salmonella-contaminated MSC have demonstrated the potential for the human pathogen to be transmitted to consumers via MSC. The current study evaluated the efficacy of multiple treatments applied to the surfaces of chicken carcass frames to reduce microbial loads on noninoculated frames and frames inoculated with a cocktail of Salmonella enterica serovar Enteritidis and Salmonella enterica serovar Typhimurium. Inoculated or noninoculated frames were left untreated (control) or were subjected to treatment using a prototype sanitization apparatus. Treatments consisted of (i) a sterile water rinse, (ii) a water rinse followed by 5 s of UV-C light application, or (iii) an advanced oxidation process (AOP) combining 5 or 7% (v/v) hydrogen peroxide (H2O2) with UV-C light. Treatment with 7% H2O2 and UV-C light reduced numbers of aerobic bacteria by up to 1.5 log CFU per frame (P < 0.05); reductions in aerobic bacteria subjected to other treatments did not statistically differ from one another (initial mean load on nontreated frames: 3.6 ± 0.1 log CFU per frame). Salmonella numbers (mean load on inoculated, nontreated control was 5.6 ± 0.2 log CFU per frame) were maximally reduced by AOP application in comparison with other treatments. No difference in Salmonella reductions obtained by 5% H2O2 (1.1 log CFU per frame) was detected compared with that obtained following 7% H2O2 use (1.0 log CFU per frame). The AOP treatment for sanitization of chicken carcass frames reduces microbial contamination on chicken carcass frames that are subsequently used for manufacture of MSC.

HIGHLIGHTS

  • Chicken carcass frames were sanitized using an advanced oxidation process.

  • Salmonella was reduced by 1.1 log CFU per frame with H2O2 and UV-C light.

  • Aerobic bacteria were reduced by up to 1.5 log CFU per frame with 7% H2O2 plus UV-C light.

  • Advanced oxidation processing produced greater reductions than water or UV-C light alone.

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Posted in food bourne outbreak, Food Micro Blog, Food Microbiology Blog, Food Microbiology Research, foodborne outbreak, foodbourne outbreak, microbial contamination, Microbiology, Research, Uncategorized, UV Microbiology