|MadSci Network: Other|
Modern packaging has come a long way from placing items in a polyethylene bag and heat sealing the top. Many packages are made up of three or more laminated films, depending upon the particular application. One layer might be aluminum to act as an oxygen barrier. Other layers might include polyethylene, polypropylene, Mylar, etc. www.packagingdigest.com is a trade publication that provides links to packaging materials and machinery. In the trade, machinery that seals bags is referred to a "form, fill, seal" equipment. It appears that most packages are still sealed by heat; the inner layer of the package is usually designed to melt and bond to its counterpart when subjected to heat and pressure. A company, CP converters http://www.cpconverters.com/Markets/nuts.htm offers packages that can be nitrogen sealed (in this case to extend the shelf life of packaged nuts. So the technology to seal products in pouches in nitrogen is certainly available in the market.
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