Experts create models to assess Listeria risks in some foods

Scientists have developed formal threat evaluation fashions for Listeria monocytogenes in sure meals.

The fashions should be examined and reviewed earlier than being made public, stated specialists at a gathering organized by the World Well being Group (WHO) and the Meals and Agriculture Group (FAO) of the United Nations.

Findings come from a Joint FAO/WHO Skilled Assembly on Microbial Threat Evaluation (JEMRA) of Listeria monocytogenes in meals in October. The main target was on leafy greens, frozen greens, cantaloupe, and ready-to-eat (RTE) seafood. A abstract has been released however a full report might be printed later as a part of the FAO and WHO Microbiological Threat Evaluation (MRA) sequence.

Outbreaks of listeriosis proceed to happen globally, with some linked to beforehand unreported meals autos, reminiscent of leafy greens, melons, frozen greens, and ready-to-eat fish.

Knowledge wanted for fashions

Following suggestions from JEMRA in 2021, Codex — a company that determines worldwide meals security requirements — is seeking to replace steerage on the management of Listeria monocytogenes in meals.

Laurent Guiller, from ANSES in France, chaired the assembly and stated it allowed scientists to develop the construction of 4 listeriosis threat evaluation fashions.

“For 3 of them, the place to begin is the contamination by Listeria monocytogenes on the main manufacturing stage. We additionally labored collectively to ascertain a way to combine genomic information. The professional group’s strategy is versatile. It opens the best way for various customers all over the world, with completely different ranges of data, to guage the effectiveness of management measures alongside the manufacturing chain as much as consumption,” Guiller stated.

Scientists stated the first manufacturing (pre-harvest) module ought to allow evaluation of the introduction of the pathogen in uncooked supplies, bearing in mind the consequences of season, agrifood practices, and local weather change. The potential for cross-contamination and recontamination from main manufacturing to consumption must also be thought-about.

The dose-response mannequin might be tailored from current fashions that take into account variability in pathogen virulence and client susceptibility. The inclusion of complete genome sequencing (WGS) and different -omics information on Listeria monocytogenes can also inform threat assessments.

Specialists stated an evaluation needs to be carried out to determine which mannequin inputs and assumptions have the best influence on the outputs. Extra information on Listeria within the meals chain from completely different sampling and testing schemes can be wanted.

Key areas for lettuce and different leafy greens

For leafy greens, manufacturing steps together with irrigation, fertilization, and different on-farm administration practices influence the prevalence of Listeria and may very well be modeled. Related levels for the chance evaluation embody progress in a area, managed surroundings or hydroponics, harvesting, cooling, washing, sanitizing, slicing, packaging, transportation steps, show at retail, and client practices.

Any mannequin ought to measure the effectiveness of the prevention of contamination by soil/irrigation water, the efficacy of washing with or with out sanitizers, the prevention of cross-contamination alongside the manufacturing chain, good hygiene practices throughout processing, the efficacy of sampling schemes, and the influence of various shoppers’ practices associated to dealing with and storage.

These factors have been additionally raised for cantaloupe. Specialists stated the chance evaluation ought to take into account cross-contamination at pre-harvest, at processing because of pooling of fruits from different producers, meals contact surfaces, gear or dicing, at retail, and on the client degree from contamination from rind to flesh throughout slicing. They added the impact of time and temperature within the provide chain was additionally essential to incorporate.

Frozen greens and seafood

Related levels within the frozen vegetable threat evaluation embody cleansing, washing, blanching, freezing, packaging, retail show, and client practices reminiscent of defrosting, cooking, and non-intended use. The evaluation ought to measure the effectiveness of blanching or different inactivation steps pre- or post-packing, prevention of contamination post-blanching, and efficacy of sampling schemes.

Scorching- and cold-smoked and gravad fish represented the RTE seafood mannequin. The chance evaluation needs to be versatile to accommodate different RTE fish merchandise sooner or later like sashimi or ceviche.

Cross-contamination needs to be within the mannequin as a result of fish is produced in a number of steps, both in a single plant or a number of services in numerous nations. The impact of lactic acid micro organism cultures on the management of Listeria needs to be evaluated within the threat evaluation and it ought to take into account uncooked supplies with completely different ranges of contamination.

Earlier this yr, FAO and WHO printed a report as a part of the MRA sequence on Listeria monocytogenes in ready-to-eat foods. A gathering in 2020 recognized a number of gaps within the FAO/WHO threat evaluation mannequin and agreed updating it will be priceless to tell threat evaluation methods.

One other MRA sequence report lined management measures for Shiga toxin-producing E. coli (STEC) related to meat and dairy merchandise. There is no such thing as a single answer to regulate STEC in all conditions. As an alternative, a number of interventions at a number of factors within the provide chain might be handiest.

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