Assuming that the foil used is free from pinholes,neither moisture
nor moisturevapor can pass through.Of couse,proper seals or closures must be used.
Aluminum foil is nontoxic even when pitted by saline soulutions.
It is insect resistant and has excellent heat conductivity;
the latter property is important both during food freezing and also during reheating.
Aluminum foil containers can be fabricated in light weights,
often an advantage both in freezing food s and in reheating them.
Although foil is highly resistant to the weak organic acids found in many food products,
it is attacked by strong mineral acids.Foil is less resistant to weak alkaline products,
hence with such products it is desirable to use foil coated with a protective film of a polyvinyl plastic.
Therefore,a packer considering aluminum foil containers for a saline or slightly alkaline food
should conduct actual storage and handling tests prior to commercial adoption of the package.
Thermoplastic coatings have been devised(approved by the FDA)that can be used for coating
aluminum foil for protection against strong food acids and alkaline food which may corrode the aluminum.
Food in plastic coated foil containers may be reheated in a microwave oven
without the objectionable arcing which occurs when frozen food is thawed
and reheated in plain aluminum foil containers in this type of oven.
These coatings are not damaged by oven heat because of their thermosetting properties.
Aluminum foil pie pans have been perfected in which a pie can be baked
with a nicely browned bottom cruse free from sogginess.
This was accomplished by perforating the bottom of the pie pan with a few pinholes
and by applying a black coating to the bottom which absorbs instead of reflects the radiant heat.
At a small cost,vivid decorative colors can be applied to the outside of an aluminum foil container.
Careful preparation and proper printing of aluminum foil give a depth
and luminosity to inks and also a dramatic pringting effect.
Color coatings have been devised that are acceptable to the
U.S.FDA for inside application aluminum foil containers.