In 2017, the American Frozen Food Institute (AFFI) embarked upon a strategic plan that prioritized the advancement of food safety across the frozen food and beverage industry around the prevention and control of Listeria monocytogenes. Over the past 3 years, AFFI has been on a journey to provide both our members and the collective frozen food industry with the best available science and best practices to ensure that frozen foods and beverages remain safe.

The deliberate emphasis on the prevention and control of L. monocytogenes came shortly after the first outbreak associated with frozen vegetables that led to heightened surveillance of frozen vegetables by both federal and state regulatory authorities, along with a wave of recalls. Recalls were issued for not-ready-to-eat frozen foods that bear on-package validated cooking instructions because they may have been contaminated with L. monocytogenes, irrespective of the level of potential contamination and the fact that frozen foods inherently do not support the growth of L. monocytogenes due to their storage temperature.

AFFI immediately implemented its strategy to collect scientific data on the prevalence and risk of L. monocytogenes in frozen food facilities, develop improved food safety and manufacturing practices, ensure that consumers follow the package cooking instructions, and lastly, to work with federal regulatory entities toward practical, science-based policies to mitigate the risks associated with L. monocytogenes. These four initiatives remain the foundation of AFFI’s mission to advance food safety in the frozen food industry while reducing the incidence of listeriosis.

Three important realities underscore AFFI’s efforts. First is the ubiquitous persistence of L. monocytogenes in food environments that makes the pathogen hardy and challenging to eliminate from any food facility. This characteristic is key to understanding how food facilities can implement environmental monitoring plans to assess and address this challenge. Second is the high incidence of illness among the vulnerable subpopulations, particularly the elderly (> 70 years), who are most impacted by foodborne listeriosis. These data present an opportunity to target specific interventions to mitigate L. monocytogenes risks and protect this important population subgroup, ultimately reducing disease burden in the U.S. Third, it is important to note that current L. monocytogenes policies in the U.S. have drifted significantly away from global regulations. Specifically, the U.S. pursues a zero-tolerance approach regardless of risk level or public health consequences associated with the presence of L. monocytogenes in a food product. Overall, the stringency of these regulatory policies has been counterproductive, undermining the food industry’s efforts to mitigate the risks associated with L. monocytogenes in foods. We need feasible, alternate approaches that balance public health goals and practical industry compliance standards.

In many regards, the food industry is at the crossroads of a scientific debate on the potential of regulatory policy, industry action, and consumer responsibility that needs to be resolved. This commentary discusses the implications of all the above for the broader food industry, but most importantly, will share how AFFI has developed a dedicated and thoughtful program in partnership with industry leaders, research experts, and policy makers across the world. This holistic effort will continue to serve as a template for tackling complex food industry issues that impact industry and public health needs.

The Risk of L. monocytogenes
Listeriosis is a serious infection caused by consuming food contaminated with the pathogen L. monocytogenes. Symptoms range from severe diarrhea to general malaise, but overall, listeriosis is treatable. It is, however, typified by a very high mortality rate, approaching nearly 20 percent in some countries, and particularly affects vulnerable populations, such as the elderly, infants, pregnant women, and immunocompromised individuals.  

Unlike other pathogens, members of the genus Listeria generally thrive in cool and moist environments at temperatures below 40 °F. Outbreaks of listeriosis have historically been associated with unpasteurized milks, soft cheeses, and deli meats, which are all stored at such temperatures. It’s important to note that the Codex Alimentarius recommendations for L. monocytogenes prevention and control address the specific risks with products stored in these low-temperature conditions, such as pathogen growth before consumption. Specifically, Codex distinguishes two product categories: one that supports growth of the pathogen and another that does not. Under Codex, frozen foods fall under this latter category of foods that do not support growth, with a tolerance recommendation of 100 CFU per gram for L. monocytogenes. Even still, listeriosis outbreaks have become increasingly associated with more diverse food categories outside the refrigerated temperature range, including caramel apples, stone fruits and other produce, ice cream, and frozen vegetables.

Due to its persistence, Listeria is generally ubiquitous in food environments such as salad bars, delis, and food processing facilities. Furthermore, in food manufacturing, there is repeated introduction of L. monocytogenes from incoming raw materials by transfer of operational personnel, tools, and equipment from within and outside the facilities, as well as from the high and uncontrolled use of water during processing. To combat the constant resurgence of L. monocytogenes, food manufacturers must apply robust sanitation programs coupled with an environmental monitoring and testing regimen aimed to seek and destroy L. monocytogenes. For the frozen food industry, these efforts are complicated by the fact that many manufacturing facilities are timeworn, lacking modernized equipment. 

AFFI’s Best Food Safety Practices
Among the first of AFFI’s efforts was to establish a food safety working group to develop best food safety and manufacturing practices. Representing over 50 frozen food companies, members of AFFI’s food safety working group developed a multifaceted library of resources, guidelines, and procedures called the Listeria Control Program (LCP, Figure 1). This program focuses on areas critical to the control and prevention of L. monocytogenes in frozen food facilities in seven core areas.

In each of the seven core areas, the LCP represents a list of more than 100 clear and concise recommendations (Figure 2). This program is unique because it not only allows food manufacturers to quickly reference each recommendation but also utilizes supporting information in the form of one or more detailed food safety resources to help implement these recommendations.

The areas of Good Manufacturing Practices, hygienic design of equipment and facilities, sanitation controls, and environmental monitoring have long been implemented to control L. monocytogenes in food facilities. However, in the LCP, AFFI’s food safety working group adapted these areas to frozen production processes.

In addition, the areas of process validation, hygienic zoning, and freezer management also provide unique opportunities for the frozen food industry to prevent and control L. monocytogenes. AFFI’s food safety working group developed process validation measures to ensure that the potential prevalence of L. monocytogenes on raw produce that enters manufacturing facilities can be reduced through thermal treatments such as blanching. AFFI’s process validation resources include how to validate equipment and processes, and establish time and temperature parameters to achieve lethality.[1]

Additionally, hygienic zoning in frozen food production facilities is also a critical component of L. monocytogenes control. After thermal processing, food products are typically exposed to the environment prior to freezing in an area commonly referred to as the postlethality region. Here, potential L. monocytogenes recontamination is a possibility, particularly on food contact surfaces. In response, AFFI’s food safety working group developed detailed operational practices[2] that prevent the potential for L. monocytogenes to find harborage in the facility and reduce contamination risks.  

Finally, freezing is unique among processing operations in food manufacturing and presents significant challenges as L. monocytogenes can survive freezing. Freezer technology and equipment are modernizing; however, the ability to clean and sanitize freezers, and monitor on a routine basis is inherently difficult. AFFI’s freezer management resources3 provide industry with best practices to eliminate L. monocytogenes risks.

In early 2019, the LCP was launched on AFFI’s Food Safety Zone,[4] a website designed to serve as a one-stop food safety collection of best practices aimed at L. monocytogenes prevention and control. The online tool has been made publicly available for free, and AFFI hopes that the resources on this website will build a food safety culture that empowers employees to make critical food safety decisions and take preventive actions to mitigate L. monocytogenes risks. While AFFI’s Food Safety Zone targets frozen food facilities, AFFI recognizes L. monocytogenes risks extend to the broader food industry and encourages all food manufacturing operations to review and take advantage of these tools.

In addition to the AFFI’s Food Safety Zone, AFFI has expanded the reach of the LCP through several partnerships to assist with implementation and measuring effectiveness of industry best practices. In December 2019, AFFI released its Listeria-specific food safety training kit5 in partnership with Intertek Catalyst, a tool that provides year-round training to help food safety managers drive effective food safety practices with their frontline operators. Frontline personnel play a significant role in food safety management within facilities, and their awareness and actions are paramount to maintain a strong food safety culture.

Even as these educational tools and resources are instrumental in empowering operation teams to prepare for and understand critical food safety steps, they ultimately have to be implemented effectively. To monitor and measure industry-wide adoption and improvement, AFFI recently launched its L. monocytogenes Trend Tracker program,6 in partnership with Mérieux NutriSciences. The program is a data collection and analysis tool to support environmental monitoring. While participation is voluntary, frozen food companies may enlist their environmental monitoring data in a way that would allow each company to analyze its own data, which can be anonymously compiled with data from other companies to develop an industry standard.

Scientific Research and Regulatory Approaches
AFFI relies on science-based research to generate knowledge to improve food safety practices as well as inform practical and risk-based regulatory approaches. The strategic investment in scientific expertise and research conducted over the past few years has yielded new modeling tools for assessing L. monocytogenes transmission and consumer exposure, and a means to understand the true public health consequences of the general prevalence of low levels of L. monocytogenes in foods. Through research, AFFI strives to encourage greater awareness and application of best food safety practices in the frozen food industry while building consensus within U.S. agencies and globally toward alternate policy approaches that will allow the food industry to practically manage these risks.

AFFI’s Frozen Food Foundation funded two disparate L. monocytogenes research programs through the University of Georgia (UGA) and Cornell University pertaining to frozen foods. The UGA research team led by Mark Harrison, Ph.D., utilized simple survey tools to collect important environmental monitoring practices prevalent in the industry to understand the baseline of activities to address L. monocytogenes risks. Specifically, UGA collected monitoring data to analyze and identify important trends in the frozen food industry and provide a baseline for future assessments. In addition, the UGA research evaluated the prevalence of L. monocytogenes in select raw vegetables to understand pathogen levels as they enter food facilities. AFFI is pleased to report that the research component7 has been completed and several publications are due to be released this summer.

Cornell’s research led by Martin Wiedmann, Ph.D., D.V.M., resulted in a novel software tool that utilizes the concept of agent-based modeling to evaluate L. monocytogenes transmission in the food production environment.[8] The methodology encompasses the heterogeneity and complexity of food production facilities and their equipment in a way that pinpoints potential L. monocytogenes transfer locations and aids food safety management decisions in a timely manner. AFFI’s premise for funding this research was to better target the persistence of L. monocytogenes in facilities. Environmental monitoring is a complex phenomenon, and modeling can serve as an excellent tool for food safety purposes.

Further research from Cornell generated a valuable risk-assessment tool to evaluate public health outcomes from the consumption of potentially contaminated frozen foods.[9] The tool assesses the risks associated with individual food product lots based on L. monocytogenes results, consumer behavior and susceptibility, and product-use scenarios. This tool will help food companies modify sampling programs and determine listeriosis risks associated with specific products. AFFI strongly believes these risk management tools are going to transition food production, food safety decision making, and public health objectives to more credible, practical methodologies, and AFFI is proud to be leading in these food safety frontiers.
Beyond food safety approaches, an important area that remains unexplored to date has been to understand the true public health consequences of the presence of L. monocytogenes in foods. Along with the support of several members of the Alliance for Listeriosis Prevention, including the National Fisheries Institute and other industry partners, AFFI funded the epidemiology research of Craig Hedberg, Ph.D., at the University of Minnesota to develop a realistic assessment of this question alongside important product formulation and consumer-use characteristics. The study examined food exposure data to evaluate patterns of acquiring listeriosis and developed a risk-categorization matrix that can assist in the development of prevention strategies. This study has also been completed and is currently being prepared for publication.[10]

Lastly, AFFI has convened an international expert panel to review current research, regulatory policies, industry practices, new technologies, and consumer behaviors as they relate to the listeriosis burden. The panel led by Jeff Farber, Ph.D., former director of food microbial safety for Health Canada, will be providing strategies to meet and potentially exceed the U.S. Centers for Disease Control and Prevention (CDC)’s listeriosis goals and provide a framework to facilitate further reduction of public health impact relative to L. monocytogenes. Most importantly, the expert panel will develop a scientific basis and rationale for alternate approaches to zero-tolerance policies regulating L. monocytogenes in foods. AFFI advocates for policy approaches and paradigm-shifting concepts to be advanced in place of the current status quo as it relates to microbiological criteria for L. monocytogenes in foods and methods to ensure these criteria both address industry’s ability to mitigate L. monocytogenes risks and meet U.S. and global public health objectives.

Consumer Education
We must ensure consumers understand most frozen foods are intended to be cooked and follow the package cooking instructions. There’s strength in numbers when it comes to sharing this knowledge. That’s why AFFI collaborates with its members and other organizations on educational strategies that effectively bring food safety messages to consumer audiences, especially to vulnerable subpopulations.

Building upon AFFI’s Best Food Safety Practices
The progress made under AFFI’s comprehensive strategy has had a tangible impact on the frozen food industry and its manufacturing facilities. Frozen food companies came together at the outset of this process to make food safety a precompetitive arena, and their collaboration, partnership, knowledge growth, and commitment to advancing food safety have been tremendous. As this evolution of the industry has been occurring to address L. monocytogenes concerns, new challenges have emerged, and AFFI has risen to the occasion again.

Last summer, several recalls resulted from the U.S. Food and Drug Administration (FDA)’s sampling program for enteric viruses (norovirus and hepatitis A) in frozen berries. These recalls led to confusing media coverage around the safety of frozen berries. As AFFI took charge to understand the nature of FDA’s sampling and testing program, important technical limitations in the interpretation of results emerged, and AFFI’s team worked with the agency to develop practical sampling and interpretation criteria. Still, there remained significant unanswered scientific questions, and AFFI sought expert counsel from leading virologists, including Lee-Ann Jaykus, Ph.D., professor at North Carolina State University, to assist with these increasingly complex technical questions.

With over seven frozen berry recalls in the span of 6 months, the frozen fruit industry has been heavily impacted by FDA’s continuation of its sampling program, at a time when no epidemiological evidence was available to trace any illnesses back to recalled products. AFFI’s alertness and competent parlay with the agency potentially eased the industry from bigger consequences, but challenges still remain. Much as it did with the L. monocytogenes strategy, AFFI has now brought together more than a dozen top virologists from across the world, (including those representing U.S., Canada, and European Union regulators and academic researchers) to coordinate and interpret science-based and risk-based approaches to the food safety management of enteric viruses in frozen berries.

Under AFFI’s leadership, the frozen fruit industry formed a food safety working group to outline best practices and recommendations for mitigating important risks associated with water, workers, and waste as they relate to the growing, harvesting, and processing of berries. AFFI also outlined a series of scientific research goals to complement the development of industry best practices and the expert panel’s technical efforts. AFFI anticipates that this work will yield similar expert-vetted, practical, risk-based approaches to guide industry’s surveillance and to inform future regulatory risk-assessment and compliance efforts. 

COVID-19 and Beyond
Over the past 2 months, the COVID-19 pandemic has affected all aspects of our world, and now more than ever, the importance of the food industry to our nation is critical. As a member-driven national trade association, AFFI is well-positioned and dedicated to guiding the frozen food industry through the important elements of worker safety, food safety, and business continuity so that their business can remain operational during and after the COVID-19 pandemic. These resources are available at

During the COVID-19 crisis, AFFI, alongside its allied food and beverage trade associations, advocated that food manufacturing be included among the critical infrastructure in the United States so that facilities could continue food production. AFFI has also developed guidance in concert with the White House, FDA, U.S. Department of Agriculture, CDC, Department of Homeland Security, and Occupational Safety and Health Administration to ensure that facilities are implementing consistent approaches so that they can remain operational. This guidance includes recommendations for screening employees,[11] what to do when an employee tests positive,[12] best practices to achieve social distancing in a facility,[13] and more.[14]

Importantly, AFFI is liaising with the White House, FDA, CDC, and other agencies to communicate the needs of the industry as they relate to labeling and other regulations. Like AFFI’s work to advance food safety, the COVID-19 response requires open communication from within and outside of the food industry with the federal government, allied organizations, and state and local authorities. And as the impact of this pandemic continues to evolve, AFFI will continue to communicate guidance and recommendations to the frozen food industry so that the farmers, fruit and vegetable growers, makers of prepared meals, suppliers, and distributors of frozen food who make up our membership can continue to produce food for our tables around the United States.

AFFI will continue to prioritize food safety across the frozen food and beverage industry. Using the best available science and best practices, we will continue to ensure that frozen foods and beverages remain safe.   

Donna Garren, Ph.D., is the AFFI executive vice president, and Sanjay Gummalla, Ph.D., is the AFFI senior vice president of scientific affairs.

12. COVID19+Case Recommended Protocols_9Apr2020_Version4.pdf.