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Polymers - Active Packaging - Intelligent Packaging.

Polymers are used to make different types of packaging for food.

What is Active Packaging?

Active packaging contains something that will interact with the
contents. Examples are cans that have something to make the
contents hot (for example coffee) or
cold or release gas (for example to form a foamy head on beer).

Some packaging contains substances which remove oxygen
or water from the contents. Both of these are needed for
the growth of microorganisms (bacteria and fungi) which cause
food to decay. Removing oxygen and water limits the growth
of microorganisms and makes the food stay fresh for longer.

Packaging may also contain a substance that chemically
the growth of microorganisms. One commonly used
substance is potassium sorbate (E202) which resists the
growth of mould and yeast. Potassium sorbate is
present in some poly(ethene) film used for wrapping cheese.

What are Intelligent Packaging and Thermochromic Packaging?

Intelligent packaging can detect changes in the contents
and give people useful information. Some substances
change colour when they are heated or cooled. These
substances are called thermochromic and they let people
know when the contents is at the correct temperature
to be used. For example, thermochromic ink is used to let
people know when the contents has been cooked for long
enough to reach the correct temperature, or when the
contents has been chilled for long enough in a refrigerator.

Some beer is sold in white cans with thermochromic ink
which turns from white to blue when the beer is cold
. The blue pattern seems to magically appear
at the correct temperature. A different type of packaging
can use the same type of ink to give an indication
if the contents have been warm for too long and
microorganisms have started to grow and cause decay.

Intelligent packaging will increasingly be used
in the future for medical and health care products.

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