The International Life Science Institute states that foods considered as high-risk sources of listeriosis include products that are ready-to-eat, require refrigeration and are stored for extended time periods.
The publication from the European Commission’s DG Health and Consumers falls under Regulation (EC) No 2073/2005 on the microbiological criteria for foods, and states that producers of RTE foods need to take certain actions to control contamination of L. monocytogenes as well as its growth in the product until the end of shelf-life.
“Knowledge and documentation of the growth potential in a food product is needed, and must be taken into account when the producer sets the safe shelf-life for the product,” said the guidance.
L. monocytogenes can contaminate ready-to-eat meat and poultry during post-processing steps such as slicing, peeling and packaging.
The key reason why this particular pathogenpresents such a problem for many food manufacturers is that, in general, food processing conditions are conducive to the growth of Listeria.
For example, L monocytogenes favours the exact conditions of a meat processing plant, such as wet floors, cool and damp walls, standing water in rough floor surfaces and moist floor drains.
The authors said that the new guidelines will help RTE manufacturers:
- to demonstrate to the satisfaction of the competent authority that the products will comply with the Community Regulation until the end of the shelf-life;
- to understand the range of different approaches available to help establish a safe product shelf-life in relation to L. monocytogenes and to decide the appropriate approach for their products; and
- to classify their products into RTE foods in which growth of L. monocytogenes can occur or in RTE foods in which growth of L. monocytogenes will not occur during their shelf-life.
The guidelines note that testing against L. monocytogenes at the end of the shelf-life may be used as verification of the efficacy of the HACCP-plan.
Novel inhibition method
Meanwhile, a recent US study has found the combination of natural antimicrobials with in-package pasteurization of ready-to-eat (RTE) turkey bologna is effective in reducing the L. monocytogenes pathogen and preventing outgrowth during refrigerated storage.
In-package pasteurization allied with nisin-lysozyme treatments was effective in reducing the bacterial population by below detectable levels by two-three weeks of storage, claim the Clemson University researchers.
The researchers claim that the intervention methods used in the study satisfy the requirements of alternative 1 of the interim final rule of the United States Department of Agriculture (USDA) in regard to its regulation aimed at controlling L. monocytogenes in plants that produce RTE meat and poultry.
Alternative 1 requires the use of a post-lethality treatment to reduce the initial bacterium and an antimicrobial agent to suppress or limit the growth of the pathogen during storage.
The researchers claim their method employs low levels of both treatments:
“This fact would help the industry in developing a cost-effective pasteurization method to control L. monocytogenes in RTE meat products and to preserve the desirable qualities of the food product,” added the research team.
The guidelines can be downloaded here