Microwave foods metals

The following points are relevant to the operation of a microwave oven. Plastics and Pyrex glasswares do not contain polar molecules and are therefore not affected by microwave radiation. (Styrofoam and certain plastics cannot be used in microwaves because they melt from the heat of the food.) Metals, however, reflect microwaves, thereby shielding the food and possibly returning enough energy to the microwave emitter to overload it. Because microwaves can induce... 

Metals tend to reflect microwaves, hence the lightning seen when we put a metallic item in a microwave oven. The microwaves energy is not absorbed by the food, and is otherwise absorbed in order to ionize the (moist) air inside the oven. 

Some packages directly enhance consumption or further preparation of the product. Probably, the most famous example is the TV dinner, which allowed meals to go from the freezer to the oven to the table. Later, the metal tray was replaced by a plastic one, permitting even faster food preparation in the microwave oven. Many packages make it easy for us to use the products they contain (e.g., squeezable bottles, reclosable liquid board containers, plastic bottles with handles, and pop-up dispenser tops). 

The concern about possible contamination of food containers means that they can be recycled to only nonfood contact uses in the United States. To reuse polyethylene terephthalate in contact with food, it must be broken down, purified (to remove metal compounds, colors, and such), and resynthesized (14.2). This has been done by hydrolysis, methanolysis, and glycolysis.162 (The solvolysis can be complete in 4-10 min when microwaves are used with a zinc acetate catalyst.163) (For nonfood uses, such as the use of polyethylene terephthalate in magnetic tapes, it may be sufficient to melt the polymer and filter out the chromium or iron oxides.164)... 

LCPs can be used in thin layers or at low concentrations in blends to make cost-effective high barrier films and containers. LCP barriers have advantages over aluminized plastics and metal foil because the LCP layers can be thermo-formed, they are microwavable, recycling is easier, and metal detection systems can be used to inspect packaged foods. 

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