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Wiping down table
Retail Food Safety Forum

Combating Norovirus in Restaurants: Proper Sanitizer and the Wiping Step Matter

By Food Safety Tech Staff
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Wiping down table

A comparative study of four commercially available sanitizers found that an ethanol-based product was significantly more effective in destroying human norovirus (hNoV), and all products tested benefited from a wiping step to physically as well as chemically remove traces of the virus.

The purpose of the study, which was published in Food Microbiology (August 25, 2022), was to assess the anti-hNoV efficacy of various surface sanitizers when applied to a laminate material commonly used for restaurant tabletops.

Researchers from North Carolina State University, in partnership with GOJO, evaluated four products with different active ingredients (ethanol [EtOH], acid + anionic surfactant [AAS], quaternary ammonium compound [QAC] and sodium hypochlorite [NaOCl]) and a water control against two human norovirus strains—hNoV GII.4 Sydney and hNoV GI.6—and the cultivable surrogate Tulane virus (TuV). They used identical spray bottles and a robotic arm to wipe the surfaces to ensure consistency in methods between products.

“We had two major research questions. First, what is the efficacy of sanitizers commonly used by the retail food industry against human norovirus? Second, what is the relative importance of including a wiping step during the sanitizing process?” said Lee-Ann Jaykus, Ph.D., William Neal Reynolds Distinguished Professor of Food Microbiology at North Carolina State University and co-author of the study. “We found that on Formica, only one of the four products tested was able to provide any significant activity against human norovirus; the other three products inactivated only a negligible amount of virus.”

The researchers used controlled antiviral surface assays to assess the relative anti-hNoV efficacy of the sanitizers, and outcomes were compared following 30- and 60-second contact times without wiping and 30- and 60-second contact times with wiping.

Following a 30-second contact time with the EtOH-based product, log10 reductions of 3.6 ± 0.7, 4.1 ± 0.5 and 3.4 ± 0.2 were observed for GII.4, GI.6 and TuV, respectively. Treatment with all other products resulted in statistically significantly lower reductions in viral titer.

Following 60-second contact time with the EtOH-based product log10 reductions of 4.0 ± 0.5, 4.3 ± 0.6 and 6.3 ± 0.5 were observed for GII.4, GI.6 and TuV, respectively. The other formulated or diluted products produced ≤0.5 log10 reductions.

The addition of the wiping step provided greater log10 reductions in virus concentration for all products tested against all viruses.

“The addition of a wiping step to the sanitation process provided removal of 95% to 99.9% of the virus on the surface,” said Dr. Jaykus.

When comparing performance among the three viruses, “The performance against all three viruses was nearly identical for each of the four products,” said Dr. Jaykus. “In other words, if Product A inactivated 50% of one human norovirus strain, it also inactivated around 50% of the other human norovirus strain and the Tulane virus. This tells us that Tulane virus might be a better surrogate than the viruses currently used as proxies for human norovirus upon which to base label claims.”

When the paper towels were processed for residual virus five minutes after wiping, no evidence of residual virus could be detected on the used paper towels with the EtOH-based product treatments. For the NaOCl-based product, no detectable virus was present on spent paper towels used in wiping studies for GII.4 hNoVs, and relatively low concentrations of virus were recovered from paper towels for GI.6 and TuV. For the AAS-based product, the concentrations of virus recovered from the paper towels were approximately 2.3, 1.3 and 1.4 log10 lower than that of the untreated control for GII.4, GI.6 and TuV, respectively. For the QAC-based product and water, the concentration of virus recovered from the paper towels was similar to that of the initial dried inoculum, suggesting low (if any) virus inactivation by the product.

“One of the most interesting findings was that the quaternary ammonium-based compound (QAC) did not show any real anti-noroviral activity against the virus strains tested. This is important because the vast majority of the restaurant and retail sector in the U.S. routinely uses QAC-based products to sanitize tables in dining areas,” said Dr. Jaykus. “Further, we were able to recover infectious virus from paper towels used to wipe contaminated surfaces, which suggests that if the sanitizer does not kill the virus, towels used in wiping could spread viruses if reused on another surface.”


2020 FSC Episode 6 Wrap: Lessons in Sanitation

By Maria Fontanazza
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COVID-19 has put a spotlight on the importance of proper handwashing and overall hygiene. In addition to focusing on worker and operational safety, it has also pushed food manufacturers and processors to pay more attention to the location of high-touch areas and how they should be cleaned, sanitized, disinfected and sterilized. During last week’s Food Safety Consortium episode on sanitation, there was discussion about the need to have the right sanitation plan and properly trained people in place. “When it comes to food safety, who are the most important people in the plant? It’s the sanitation crew and employees. They are on the frontlines, ” said Shawn Stevens, founder of Food Industry Counsel, LLC. “If they don’t do their job or are not given the tools to do their jobs, that’s where the failures occur. We need to empower them. We have to invest in sanitation and not be complacent.”

Investing in a sanitation plan is where it all begins, said Elise Forward, president of Forward Food Solutions. Within the plan, companies need to include items such as PPE and sanitation equipment, along with what resources will be needed and what chemicals will be required. “What would it look like in our manufacturing facilities if we had a plan for the pandemic?” asked Forward. “There was so much scrambling: ‘How do we do this and what do we do’. We need to plan for these events.” Forward, along with David Shelep, microbiologist and consultant for Paramount Sciences and Bill Leverich, president of Microbiologics, Inc., offered a strong overview of the right components of a sanitation plan and the common products and technologies used in the process (quaternary ammoniums, sodium hypochlorite, ethyl alcohol, peracetic acid, hydrogen peroxide, and chlorine dioxide). They also provided insight on some of the products and technologies that are being explored in the face of COVID-19—UV-C and hypochlorous acid, which has applications in cleaning biofilms, hand sanitizing, fogging, and surface application (i.e., electrostatic spraying, mopping).

“Cleaning and sanitizing is setting up your production team(s) for success.” – Elise Forward, Forward Food Solutions

View the list of EPA-registered COVID-19 disinfectants.

Beyond sanitation methods, companies need to invest in employee training and be committed to their safety. This means giving employees sick days and not incentivizing them to come to work when they are sick.

Rob Mommsen, senior director, global quality assurance and food safety for Sabra Dipping Company, shared a candid perspective on how Sabra developed an effective and validated Listeria environmental monitoring program (LEMP) following an FDA inspection that led to a swab-a-thon, findings of resident Listeria in the plant, and a huge product recall as a result of the Listeria contamination in the plant (Mommsen stated that Listeria was never found in product samples). “We had to severely alter the way we cleaned our plant,” he said. And the company did, with a number of changes that included taking the plant apart and cleaning it; removing all high pressure water nozzles; changing areas in the plant from low care to high care; keeping movable equipment to certain areas in the plant; changing employee and equipment traffic patterns; and retraining staff on GMPs. The company also changed its microbiological strategy, conducting daily swabbing in certain zones, increasing testing on samples, and implementing a weekly environmental meeting that was attended by senior and department managers. “Fast forward” to 2019: FDA conducted an unannounced audit and noted that Sabra’s environmental monitoring program was one of the best they’ve seen and that the company’s culture was clearly driven by food safety, according to Mommsen.

Fast forward again to 2020 and the pandemic: With work-from-home orders in place and other frontline workers staying home for various reasons, the company saw a change GMP adherence, employee training and the frequency of environmental monitoring, said Mommsen. So Sabra had some work to do once again to re-right the ship, and Mommsen presented it as a lessons learned for folks in the food industry: In addition to employee safety, food safety must be the number one priority, and having the support of senior management is critical; the turnaround time for environmental swabs is also critical and an effective LEMP should consist of both conventional testing as well as rapid detection technology; and an environmental monitoring program requires persistence—it is not self sustaining and there are no shortcuts.

The watch the presentations discussed in this article, register for the 2020 Food Safety Consortium Virtual Conference Series, and view the session on demand.