Uses of Packaging Materials

This section presents a summary of packaging materials and some of their uses. 

Meat and poultry low temperature durability high temperature durability (microwave) coextruded or laminated EVA ionomers, PVDC, nylon, polyester 

Snack food good machinability print-stiffness barrier properties cellophane, OPP, polyester, HDPE 

Cheese barrier properties strength laminations or coextrusion with PVDC on a base film of cellophane, polyester, nylon or PP 

Bakery products machinability low costs coated or coextruded OPP, cellophane 

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More efficient packaging - such as smaller pack sizes to reduce use of packaging material and reduce transport and distribution costs per dose [58]. 

The correct specification and use of packaging materials requires effective exchange of information up and down this chain of use. It also requires an understanding of chemical migration and the main factors that control it. 

The modem history of packaging is one of change, often but not always leading to improvement, and the readers of this book, particularly those with a career in the supply or use of packaging materials, must above all maintain an awareness of changes to materials, specification, standards and regulatory legislation. 

There is no doubt that for the municipal collection of organic waste biodegradable bags should be recommended. From an ecological point of view the Mater-Bi bag has to be given preference over the other compostable bag (paper bag "haushalt kompost"). Short routes of transport and minimal use of packaging material should be weighty criteria as for the choice of product. 

Potato chips are fried to a final moisture level of 3% or less, which accounts to an of about 0.2. Tortilla chips, corn chips, and other snacks have a final moisture content of <3%. From a study on potato chips a moisture content of 3.57% was the point at which a taste panel rejected the chips because of their texture deterioration [39]. Moisture absorption and the consequent deteriorative changes can be prevented by the use of packaging materials with appropriate moisture barrier properties. In this case the shelf life of the products can be extended to several months. If the packaging material is not transmitted by light and if the air inside the packaging is replaced by an inert gas, e.g., nitrogen, a considerably longer shelf life can be obtained. 

The packaging equipment must be well maintained for efficient performance. Clean and smoothly miming equipment makes better use of packaging materials than machinery that has not been kept in good condition and also stops unnecessary wastage of the product itself. 

Flexible packaging flexible packaging refers to the use of packaging material that is flexible, such as paper, film, or extruded plastic material, flexible packaging provides protection for food and industrial products. 

Packaging. Because of the extremely broad demands on the mechanical properties of packaging materials, the entire range of ceUular polymers from rigid to flexible is used in this appHcation. The most important considerations are mechanical properties, cost, ease of appHcation or fabrication, moisture susceptibUity, thermal conductivity, and aesthetic appeal. 

The selection of an appropriate steam-sterilization cycle must be made after a carefiil study of the nature of the articles to be sterilized, the type and number of organisms present, type and size of each package, and type of packaging material used. Cycle-development studies may be conducted using fiiU autoclave loads. 

Hospital steriliza tion is more limited in the availabiHty of steriliza tion methods and of packaging materials. Microbial invasion can occur particularly when articles are wrapped in traditional fabrics such as muslin (140-thread-count cotton). The expected shelf life of hospital-wrapped and sterilized articles is considered to be ca 21—30 days when a double-wrapping technique is used. Double-wrapping requires two successive wraps, each having a layer or layers of an approved packaging material. 

The use of safe materials is vital for barrier appHcations, particularly for food, medical, and cosmetics packaging. SuppHers of specific barrier polymers can provide the necessary details, such as material safety data sheets, to ensure safe processing and use of barrier polymers. 

Miscellaneous Uses. Inks used by inspectors to stamp the grade or quaUty on meat must, bylaw, be made from food-grade colors. Dyes used in packaging materials that come in direct contact with a food must also be food-grade or, if not, it must be estabUshed that no part of the colorant used migrates into the food product. Pet foods, too, if colored, must contain only those colorants recognized by the FDA as suitable for the purpose. 

As with textiles the principal reasons for the coloring paper are for aesthetic appearance and utihtarian purposes. Aesthetic appearance includes colored background for printed material, colored writing papers, colored household products to harmonize with interior decor, and many other diverse uses dictated by individual tastes. Utihtarian purposes include identification of multicopy forms, identification of manufacturer or marketer of specific materials or products, opaqueness or hiding power of packaged material, or to control consistency of paper manufactured from various colored raw materials. 

Compared with more common plastics used as packaging materials, the compound does have some disadvantages, such as a high water vapour permeability and limited heat resistance, losing dimensional stability at about 70°C. It is also substantially more expensive than the high-tonnage polyolefins. Last but not least its biodegradability means that it must be used in applications that will have completed their function within a few months of the manufacture of the polymer compound. 

An important selection of materials to packaging, particularly food, is based on the permeability of the materials to oxygen, water vapor, and, in the case of packaging bananas, to ethylene gas that is used to artificially ripen the bananas. Selective permeability provides chemical separations, one of the most interesting of which is the use of PTFE materials to separate the hexafluorides of the different isotopes of uranium. 

Among the commonly used flexible packaging materials, aluminum foil probably provides the most complete permeation barrier while paper is the most permeable. Although aluminum foil provides a barrier to moisture, gas, grease, and light, it usually needs protection from the contents of the package and from the environment since it is a soft metal and subject to chemical attack. 

This review is concerned with the engineering thermoplastic uses of polyamide materials in injection moulding and extrusion applications. Types of polyamides are described, and their key properties are considered. Commercial applications in the automotive, electrical/ electronic, engineering and construction, and packaging industries are discussed. Polyamide processing is... 

Confusion as to what constitutes municipal waste is presenting an obstacle to the use of packaging waste as a fuel in cement kilns. Whilst cement kilns can bum hazardous waste, they cannot bum a wide range of non-hazardous materials, it is reported. The case of Castle Cement is described which planned to bum a range of non-hazardous commercial and industrial wastes. Some waste-fired combustion processes, however, such as UK Waste s Fibre Fuel operation have been granted derogations where fuel is manufactured by advanced mechanical processes, which includes the production of fuel pellets. This latter process would be pointless for the cement industry since their fuels have to be pulverised. The problems are further discussed with reference to current European legislation. 

Membrane diffusion illustrates the uses of Fick s first and second laws. We discussed steady diffusion across a film, a membrane with and without aqueous diffusion layers, and the skin. We also discussed the unsteady diffusion across a membrane with and without reaction. The solutions to these diffusion problems should be useful in practical situations encountered in pharmaceutical sciences, such as the development of membrane-based controlled-release dosage forms, selection of packaging materials, and experimental evaluation of absorption potential of new compounds. Diffusion in a cylinder and dissolution of a sphere show the solutions of the differential equations describing diffusion in cylindrical and spherical systems. Convection was discussed in the section on intrinsic dissolution. Thus, this chapter covered fundamental mass transfer equations and their applications in practical situations. 

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