6.8 Material Used for Packing Thermally Processed Foods
Some of the most common types of packaging materials are described below:
| Container description
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Observations
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Steel body cans "tin can"
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- Steel body cans with a thin layer of tin ('tin cans") are the most widely used containers.
- Can withstand high temperatures and pressure differentials
- Not readily breakable
- The can lids provide a good indication of the presence of a vacuum and thus a hermetic seal (a seal that is impervious to the transmission of gases, water and microorganisms)
- The steel, and very often the tin plating, must be protected with lacquers to minimize reaction of the metals with food constituents.
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Glass jars
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- More resistant to corrosion and reaction with food constituents
- Allows the consumer to see the contents in the container.
- Glass is heavy and bulky and must be packaged with extra protection to prevent physical breakage of the glass during transportation
- Glass filled containers must also be processed in the retort with extra care to prevent breakage due to thermal shock.
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Sterile cartons (Tetra Pak)
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- Made from laminated plastic, aluminum and paper (click here for a Tetra Pak carton)Link (Links to an external site.)
- If you have an UHT juice or milk container in your home you may wish to look at the laminate film after you have used the contents. Can you locate most of the layers of the laminate?
- Carton laminates are first sterilized by treatment with hydrogen peroxide followed by forming and filling of the cartons under sterile conditions. A chemical sterilizing agent must be used for this type of packaging material since exposure of the laminated material to high temperatures required for heat sterilization would destroy the packaging material
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Retortable pouch
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- The retortable pouch is a relatively new form of packaging. The pouch is made of a laminate of plastic films and aluminum.
- heat penetrates these pouches faster due to their thinner profile, allowing the 12D thermal process at the cold point to take place in a much shorter period of time than the conventional metal can or glass bottle.
- Nutrient retention is superior in foods thermally processed in the retortable pouch.
- The pouch itself must be packaged in an outer protective carton to minimize physical damage to the food due to handling by the consumer and to avoid inadvertent puncture of the container
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Plastic cans/bottles
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- New types of plastic packaging materials that can be produced in the shape of a can or bottle
- Can be hermetically sealed and thermally processed in a steam retort to achieve the 12D process for low acid foods.
- Newer plastic bottles can be used with UHT-Aseptic packaging technologies
- Some of these containers are used for foods that are ready to eat. These containers, unlike metal cans and glass bottles can be placed in the microwave oven.
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