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In pack heat pasteurization of ready to eat meals


Key words heat pasteurization, shelf life extension, ready to eat meals
Latest version 2012/04/06
Completed by FRIP

How does it work?

Primary objective Combination of packaging material and heating method to prolong substantially the shelf life of ready to eat meals.
Working principle Ready to eat meals represents combination of ready to eat food packed in appropriate packaging material that enables heat treatment after packaging prolonging the shelf life of the product. As mentioned in [1] ready-to-eat meal (RTE) offers more convenience choice to consumers than buying all ingredients and cooking at home. The structure of the packaging material is a topic of research considering also the influence on environmental concern. This process requires keeping several requirements before final heat treatment in packed form. There is the microbial quality of packed food, microbial quality of packing bags before filling (aseptic or sterile character), barrier properties of the packing material and its long term stability not influenced by the heat treatment of the packed product. The main parameters influencing the shelf life of the packed product are the heat treatment parameters: holding time and holding temperature and method of the heating (steam, microwave, hot water). Also final cooling speed can influence the quality of packed RTE product.

In further text we have selected some examples of papers dealing with some of the above mentioned parameters. Paper [2] is focused on oxygen and moisture barrier properties of films for military food packaging, in particular an alternative meal bag for use in military ration packaging. In [3] there is documented how the shelf life of the packed product can be prolonged by preliminary ozone treatment before packaging. Fresh-cut red peppers were treated with 0.7 ppm ozone for 1, 3 and 5 min. Untreated fruit were used as a control. Pepper strips were packaged in polypropylene trays in air and stored at 10°C for 14 days. On every evaluation date, an important reduction in the counts was observed for psychrotrophic bacteria and also for yeasts and moulds. Results indicated that O3 combined with modified atmosphere could reduce microbial counts and extend the shelf-life of minimally processed red bell peppers.
Paper [4] describes effective method of microwave heating for different holding times (0-, 5-, 6-, 7-, 8-, 9-, and 10-seconds) of packed white bread slices to inactivate molds growing frequently on this type of bread. Shelf life of 60 days was tested and growth of molds tested. In paper [5] the authors presented method how to predict risk profiles of pork and poultry meat using an Excel-based software program, Risk Ranger. It is a semi-quantitative risk estimator answering various questions relating to the probability of exposure to a hazard, susceptibility of the population of interest, severity of the illness caused by the hazard if present and probability of food containing an infectious dose.

Additional effects Any error in completing of the ready to eat meals can shorten substantially the shelf life of the product. The best method of the production is based on microbial decontamination of foods before the packaging, right packaging into proper pouches and final heat treatment to decontaminate the product. This last decontamination procedure can eliminate the microbial contamination caused by manipulation during packaging.
Important process parameters packaging, heat treatment of packed product, refrigerated storage temperature during the shelf life
Important product parameters preliminary decontamination methods of components, preliminary cooking of ready to eat meals, design of the good taste of the ready to eat meals

What can it be used for?

Products Ready to eat meals can be composed of meat pieces, cooked pasta, sauces, vegetable salads, bread, packed in convenient packaging materials that protect meals against oxidation and contamination during storage time.
Operations Preparation of ready to eat meals by cooking, packaging, heating of packaged product, storage of product at cold temperatures (below 5°C).
Solutions for short comings Modern methods of heating of packed ready to eat meals eliminate previous problems of inefficient non-uniform heating procedures connected with heating in steam retort pouches.

What can it NOT be used for?

Products Solid dry foods that cannot be well heated and inactivation of microorganisms is not effective. Solid foods with very sharp edges penetrating the plastic packaging material. Packaging materials that present no sufficient barrier against oxidation.
Operations Very high (above 120°C) heating temperatures that decrease product and packaging material quality.
Other limitations No preliminary microbial decontamination of components, gentle and non-uniform thermal heating of the packaged ready to eat meals.
Risks or hazards Increase of storage temperature, mistake in composition of ready to eat meals.


Maturity Classical heat treatment of ready to eat meals represents the traditional production method. Novel technologies are introduced into this area (microwave heating, new packaging materials, new preliminary treatment of components such as ozonization or high pressure pasteurization).
Modularity /Implementation Current production of ready to eat meals is continuous large scale production.
Consumer aspects Longer shelf life of ready to eat meals is attractive.
Legal aspects No limitation. Only local standards for microbial content of ready to eat meals.
Environmental aspects RTE meals that are packed and heat treated can be stored at room temperatures instead of refrigeration temperatures. This is the process savings energy necessary for chilled storage.

Further Information

Institutes National Institute of Biological Resources, Public University of Navarra, IRTA, Agricultural University of Athens, UMII - EVAP
Companies U.S. Army Natick Soldier Research
References [1] Panyarjun, O., Olarikabutr, T., A study of RTE structural packaging design, (2011) Advanced Materials Research, 308-310, pp. 1759-1765.

[2] Pigeon, G., Burke, M., Investigation of multilayer barrier films for food packaging, (2011) Annual Technical Conference - ANTEC, Conference Proceedings, 3, pp. 2454-2457.

[3] Horvitz, S., Cantalejo, M.J., Combined effects of gaseous O3 and modified atmosphere packaging on quality and shelf-life of fresh-cut red bell pepper, (2010) Acta Horticulturae, 858, pp. 335-340.

[4] Lakins, D.G., Echeverry, A., Alvarado, C.Z., Brooks, J.C., Brashears, M.T., Brashears, M.M., Quality of and mold growth on white enriched bread for military rations following directional microwave treatment, (2008) Journal of Food Science, 73 (3), pp. M99-M103.

[5] Mataragas, M., Skandamis, P.N., Drosinos, E.H., Risk profiles of pork and poultry meat and risk ratings of various pathogen/product combinations, (2008) International Journal of Food Microbiology, 126 (1-2), pp. 1-12.

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Created by Milan123 on 6 April 2012, at 13:35