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Use of High Hydrostatic Pressure for the Control of L. monocytogenes in Ready to Eat (RTE) Meats and Poultry

Health Canada has notified Santa Maria Foods Inc. that it has no objection to the food use of Ready to Eat (RTE) meats and poultry which have been treated by high hydrostatic pressure (HHP) for the control of Listeria monocytogenes. The Department conducted a comprehensive assessment of these RTE meats and poultry according to its Guidelines for the Safety Assessment of Novel Foods. These Guidelines are based upon internationally accepted principles for establishing the safety of novel foods.

Background:

The following provides a summary of the notification from Santa Maria Foods Inc., and the evaluation by Heath Canada and contains no confidential business information.

1. Introduction

The high hydrostatic pressure (HHP) process consist of applying a high pressure to a packaged food via compressed water. Prior to pressurization, packaged foods are loaded in the tray, which is itself loaded into a closed chamber. The chamber is sealed and then pressurized by injecting water into the chamber until a defined pressure specific for the food to be treated is reached. The packaged food is thus immersed in the pressurized water and is submitted to high hydrostatic pressure. The proposed process is run in batch mode for prepackaged foods; other units also exist which can be run in continuous mode, for easily pumped liquid foods (juices, purees, sauces, etc.).

The length of this phase determines the efficacy of the inactivation. The high hydrostatic pressure does not affect any of the structural components of the food itself (structural proteins, fibers, fats, etc.), nor does it affect the structural integrity of the package used, as the pressure is applied uniformly on the food and the package.

The HHP process is proposed for use as a post-processing, post-packaging intervention step for the control of L. monocytogenes in RTE meats. In this context, it is an additional intervention step to enhance the microbiological safety of such products.

For clarity, RTE meat means meat or poultry products which already have been subjected to a process sufficient to inactivate vegetative pathogenic micro-organisms or their toxins and control spores of foodborne pathogenic bacteria so that the meat product does not require further preparation before consumption, except, in certain cases, washing, thawing or exposing to sufficient heat to warm the product without cooking it. It excludes raw meats or meat products requiring further processing before being safely consumed1.

The assessment conducted by Food Directorate evaluators determined the efficacy of the high pressure process in inactivating L. monocytogenes in the notified foods, how the composition and nutritional quality were affected by the process; and the potential for the presence of any toxicants, allergens or chemical contaminants due to the use of the process. Based on the information provided by Santa Maria Foods, the evaluators have not identified any safety or nutritional concerns regarding the use of this process on RTE meats.

The Food Program has a legislated responsibility for pre-market assessment of novel foods and novel food ingredients as detailed in the Food and Drug Regulations (Part B, Division 28). HHP-treated RTE meats are considered novel foods, as per B.28.001, as they have been manufactured by a process that has not been previously applied to those foods, and causes the foods to undergo a major change, the major change being, in respect to these foods, a change that places the food outside the accepted limits of natural variations for that food, with regard to microbiological safety.

1 Meat Inspection Regulations, 1990, Section 2
http://laws.justice.gc.ca/en/showtdm/cr/SOR-90-288//?showtoc=&instrumentnumber=SOR-90-288

2. Development of the novel food

Batch high hydrostatic pressure units consist of a pressure chamber, and a tray for the packaged food to be treated. Prior to pressurization, packaged foods are loaded in the tray, which is itself loaded into the chamber. The chamber is sealed and then pressurized by injecting water into the chamber until a defined pressure specific for the food to be treated is reached. The packaged food is thus immersed in the pressurized water and is submitted to high hydrostatic pressure.

Packaged RTE meats will be loaded in the pressurization chamber and the chamber will be pressurized to 87 000 PSI (or 600 MPa), which is maintained for 3 minutes. The pressure is released and the treated packages are packed and ready for shipping. Treated packages still require refrigeration.

The process is proposed for use on all RTE meats packaged in flexible films. Data was provided on RTE meats with higher water activity (above 0.9, i.e., with higher moisture), such as ham and sliced turkey, and lower water activity (below 0.9, i.e., fairly dry products), such as sliced prosciutto and salami.

4. Dietary Exposure

It is not expected that dietary exposure to treated RTE meats would be any different to that of any their untreated counterpart. In the population who will be consuming them, these products will likely fully or partially replace their regular counterparts.

5. Chemistry

The impact of the HHP treatment on the chemical safety of the RTE meats, and more specifically, on the potential for chemicals from the packaging material used in wrapping the RTE meats to migrate from the packaging material to the food matrix.

After examining the chemical composition of the ingredients used in the manufacture of the package that will be used by Santa Maria Foods and considering: a) the negligible effect on the total migration of components used in the manufacture of the laminated films/articles, and b) the fact that the Food Directorate would have no objection to the use of these materials under normal atmospheric pressure, there is no objection to the use of these materials with respect to the HHP treatment of the packaging materials as per Santa Maria Foods's intended end-use applications.

It should be noted that the packaging material authorization process is independent from the novel food authorization process. Any requests concerning the acceptability of packaging materials to high pressure treatment, the packaging material companies should be directed to the CFIA, to obtain proper clearance. As necessary, CFIA will contact the Food Packaging Materials & Incidental Additives Section to obtain an opinion on the safety of the packaging material used with novel processes.

6. Microbiology

Santa Maria Foods provided data demonstrating the efficacy of the process in inactivating L. monocytogenes in various RTE meats. The Bureau of Microbial Hazards (BMH) has assessed the impact of the HHP treatment in mitigating the presence of L. monocytogenes in these RTE meats. Data were provided for two different high pressure units on various RTE meats. Both units work on the same principle.

In a study to investigate the effects of HHP on L. monocytogenes, data were provided on prosciutto (whole and sliced), cooked ham (sliced) and salami. Each of these meats was spiked with a 5-strain cocktail of L. monocytogenes . A high level inoculation with approximately 6 log colony forming units (CFUs)/g meat was performed. These experiments were done at 87 000 PSI for 0, 2, and 3 minutes. Treated and untreated samples were assessed for survivors on days 2 and 10.

This data demonstrates that the application of 87 000 PSI for 3 minutes is sufficient to achieve a more than 4.5 log reduction in L. monocytogenes populations in all treated meats. No survivors were detected after 10 days post treatment by direct count.

Data were also provided on inactivation of the overall microbial flora (total aerobic count, lactic acid bacteria, yeast and mold, coliforms, and L. monocytogenes ) on prosciutto (whole and sliced), Genoa salami (sliced), porchetta (sliced), cooked ham (sliced) and rosemary ham (sliced). In comparison to untreated controls, for a 2 and 3 minute treatments, the residual flora was always below 10 CFU/g for total aerobic count, lactic acid bacteria, yeast and mold, and coliforms, and always negative for L. monocytogenes.

In another study to determine the effect of HHP on L. monocytogenes, data were provided on sliced cooked turkey. A high level inoculation with approximately 5 log colony forming units (CFUs)/g meat was performed. These experiments were done at 87 000 PSI for 0, 1, 2, and 4 minutes. Treated and untreated samples were assessed for survivors at day 0 and 10. This data demonstrates that application of the 87 000 PSI for at least 2 minutes is sufficient to achieve a more than 4 log reduction in L. monocytogenes population in all treated meats. No survivors were detected after 10 days post treatment by direct count.

Based on these data, there was no objection, from a microbiological standpoint, to the use of high hydrostatic pressure on prepackaged RTE meats and poultry, as proposed by the company, i.e., using a pressure of 87 000 PSI for 3 minute for the control of L. monocytogenes.

7. Nutrition

Published literature on the effects of HPP on nutrient composition indicates that the effects are minimal, and compare favourably with classic food processing treatments such as pasteurization or sterilization. The review of available published literature suggests that very high pressure treatment could possibly result in lipid oxidation and/or small peptide formation. Increases in peroxidised lipids or bioactive peptides could pose health risks, and may cause quality deterioration of food products. In one study, increased lipid oxidation in pressurised meat was reported at 800MPa/19oC/20min. In another study, treatment of meat products at 600 MPa for 10 minutes did not result in the release of peptides or amino acids. The 600 MPa/3 min treatment proposed by the petitioner is not expected to impact the nutritional safety or quality of RTE meats. Proposals for treatment of foods at higher pressure should be considered on a case by case basis.

8. Toxicology

With respect to the possible generation of toxic compounds from components of meat, the potential for high pressure treatment to cause a breakdown in protein and generate more nitrites and nitrates than are already present in the food was investigated. Increased content of nitrites and nitrates would be a concern since nitrites can react with the amines in foods to form nitrosamines which are genotoxic carcinogens, and nitrates can be converted to nitrites. Further it was possible that high pressure treatment could result in a sufficient amount of heat being applied to the food, which could result in the proteins in the food reacting with other components of meat to form heterocyclic amines, a group of genotoxic carcinogens.

The petitioner provided compositional data showing that there were no significant changes in the amounts of nitrites or nitrates in the high pressure treated meat when compared to the amounts of these substances in non-treated meat. Further, a mutagenicity assay was conducted using reconstituted freeze-dried meats as test samples, and no significant difference in mutagenicity was observed between samples of high pressure treated and non-treated meats.

It was concluded that high pressure processing as described by the petitioner did not increase the amount of nitrate and nitrite or of mutagens in the high pressure treated meats compared to the amounts present in non-treated counterparts.

9. Labelling

The HHP process described above does not cause a significant compositional change in the food, nor has there been any safety concerns raised by the use of this process in RTE meats. Based on this, the evaluation team recommends that mandatory labelling requirements are not necessary in this case.

Conclusion:

Health Canada's review of the information presented in support of the food use of RTE meats and poultry which have been treated by a high hydrostatic pressure of 87 000 PSI for 3 minutes, concluded that this use does not raise concerns related to safety. Health Canada is of the opinion that those treated RTE meats and poultry are as safe as other RTE meats and poultry on the market.

This opinion is solely with respect to the suitability of these RTE meats and poultry. It is the continuing responsibility of Santa Maria Foods Inc. to ensure that their products are in compliance with all applicable statutory and regulatory requirements. Any new information obtained in relation to these products which have potential health and safety implications should be forwarded to Health Canada for our consideration in order to ensure the continued safety and integrity of all foods available in the Canadian marketplace. The sale of a food which poses a hazard to the health of consumers would contravene the provisions of the Food and Drugs Act.


This Novel Food Information document has been prepared to summarize the opinion regarding the subject product provided by the Food Directorate, Health Products and Food Branch, Health Canada. This opinion is based upon the comprehensive review of information submitted by the petitioner according to the Guidelines for the Safety Assessment of Novel Foods.

(Également disponible en français)

For further information, please contact:

Novel Foods Section
Food Directorate
Health Products and Food Branch
Health Canada
Tunney's Pasture
Ottawa, Ontario K1A 0L2
Telephone: (613) 941-5535
Facsimile: (613) 952-6400
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