Introduction 

Ensuring product quality and food safety is critical for the frozen food industry to have greater consumer confidence and acceptance in domestic as well as export markets. The risk of foodborne disease outbreaks due to contaminated frozen foods and product recalls remains a major challenge for the global frozen food industry. Despite the strict regulations and highly prescriptive industry guidelines, Listeria monocytogenes and Salmonella outbreaks associated with a range of raw & ready-to-eat (RTE) frozen foods continue to occur across the globe. USA had a nationwide recall involving L. monocytogenes contaminated IQF corn and peas in 2016 and broccoli in 2017. There were multiple international recalls in 2018 due to contaminated IQF potatoes and IQF vegetable blends. In July this year, Tyson Foods voluntarily recalled 8.5 million pounds of frozen RTE chicken products due to possible contamination with L. monocytogenes. Similarly, there have been many recent recalls/ alerts raised against Salmonella contamination in frozen foods. The most recent illness in the UK in December 2020 was linked to Salmonella contaminated frozen breaded chicken products from Poland. The USDA issued public alerts for the Salmonella outbreak traced to frozen chicken products in 2021.  

Indian frozen food export rejections and food safety hazards  

Several Indian frozen food exporters have suffered economic losses due to rejections of their shipments. Earlier this year, an Indian frozen food company had to recall frozen RTE shrimp from US markets due to suspected Salmonella contamination. Other rejection causes of frozen shrimp shipments by the USA in the recent past include antibiotics/drug residues and adulteration with chemicals/ poisonous substances. Whereas the rejection caused by the EU in the recent past include cadmium, antibiotic and drug residues for frozen seafood; Salmonella, E. coli and pesticides for products in frozen fruits & vegetable category; sesame seeds contaminated with ethylene oxide used in frozen bakery products. Historically, microbiological causes dominated the rejections of Indian shrimps by the USA while chemical hazards were the major cause for rejection of shrimps by the EU and Japan. L. monocytogenes and Salmonella are the most known foodborne pathogenic microorganisms that cause severe infections and foodborne illness globally. The presence of Listeria and Salmonella in domestically consumed food in India represents a significant public health risk (1-5). This is further complicated by the absence of epidemiological data on foodborne Listeriosis & Salmonellosis from India and the absence of foodborne disease monitoring and surveillance.  

Freezing only prevents the growth of these two pathogens and does not eliminate them, these may survive frozen storage, recover during thawing and then grow in the food under favourable conditions. Therefore, frozen food manufacturers should formulate RTE foods with intrinsic characteristics (like pH ≤ 4.4, water activity ≤ 0.92, presence of antimicrobial compounds etc.) which do not support the growth of Listeria and Salmonella monocytogenes. Manufacturers must also monitor strictly the handling and storage procedures to control the conditions favouring the survival and multiplication of these pathogens in the cold chain. L. monocytogenes and Salmonella can persist in the processing environment for several years even under adverse environmental conditions. This makes it very challenging to eliminate these from food manufacturing facilities and hence facilities must implement Environmental Monitoring Program (EMP) to verify the control of Listeria sp. and Salmonella.  

Lack of harmonization of standards  

Differences in regulatory standards also pose a challenge for the manufacturers. The FSSAI standards stipulate that L. monocytogenes and Salmonella should be absent in 25 g of frozen products for certain product categories. Many countries including the EU have microbiological criteria for L. monocytogenes of 100 CFU/ gram for low-risk foods that do not support the growth of the organism, whereas the USA pursues a zero-tolerance approach regardless of risk level associated with the presence of L. monocytogenes in a food product. US FDA also requires manufacturers to implement EMP as verification activities for sanitation controls against these two pathogens for certain RTE products. With new research and changes in the epidemiology of listeriosis outbreaks, the FAO/WHO JEMRA is now undertaking a new assessment on L. monocytogenes in RTE foods and considering additional food vehicles and full farm-to-fork risk assessment. 

Need for consumer education on frozen foods  

With significant growth in the frozen foods market in India in the recent past, the regulator and the industry should make efforts to increase the awareness of consumers on the effective handling of frozen foods. The handling of frozen foods by retail/ e-commerce and consumers can affect the safety of frozen food. Though product and storage standards are stipulated for frozen foods by FSSAI, the actors in the supply chain do not have a clear understanding of the food safety risks of frozen foods and the impact of temperature abuse. Consumers should be made aware of the distinction between Ready-To-Cook (RTC) and RTE frozen foods w.r.t. food safety implications, the importance of adherence to cooking instructions and what to do in case of temperature abuse. The industry should also provide advice to consumers regarding good practices for thawing of frozen foods, storage conditions and time limits for consumption of thawed foods, considerations for further use/ storage of thawed foods.  

Way forward  

While most players in the industry have certifications for private/ voluntary standards (food quality and safety management systems), the ongoing foodborne outbreaks, regulatory alerts and product recall indicate that these certifications alone do not ensure food safety. The manufacturing facilities need to adopt more science or risk-based approaches to effectively control the major pathogens and other safety hazards. Data on the epidemiology of Listeria and Salmonella in India and having surveillance and monitoring mechanisms for foodborne pathogens will help in drawing necessary guidelines for the industry to adopt.  

References: 

1. Shakuntala et al, 2019. Food Biotechnol. 33: 237-250. 

1. Alka et al., 2019. FEMS Microbiol. Lett. 366, fnz111 

1. Menon et al., 2021. Vet World. 14: 777-783 

1. Prabhakar et al., 2020. J. AOAC Int. 103: 1361-1365 

1. Dutta et al., 2015. Front. Environ. Microbiol. 1:14-18 

Author:

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