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7
Plastics in food packaging
Mark J. Kirwan and John W. Strawbridge
7.1
7.1.1
Introduction
Definition and background
The most recent EU Directive relating to ‘plastic materials and articles intended
to come into contact with foodstuffs’ (reference 2001/62/EC) defines plastics
as being: ‘organic macromolecular compounds obtained by polymerisation,
polycondensation, polyaddition or any similar process from molecules with
a lower molecular weight or by chemical alteration of natural macromolecular
compounds’.
Plastics are widely used for packaging materials and in the construction of
food processing plant and equipment, because:
• they are flowable and mouldable under certain conditions, to make sheets,
shapes and structures
• they are generally chemically inert, though not necessarily impermeable
• they are cost effective in meeting market needs
• they are lightweight
• they provide choices in respect of transparency, colour, heat sealing, heat
resistance and barrier.
Referring again to the Directive, molecules with a lower molecular weight are
known as monomers and the macromolecular compounds are known as polymers – a word derived from Greek, meaning many parts.
The first plastics were derived from natural raw materials and, subsequently,
in the first half of the 20th century, from coal, oil and natural gas. The most
widely used plastic today, polyethylene, was invented in 1933 – it was used in
packaging from the late 1940s onwards in the form of squeeze bottles, crates
for fish replacing wooden boxes and film and extrusion coatings on paperboard for milk cartons.
In Europe, nearly 40% of all plastics is used in the packaging sector, and
packaging is the largest sector of plastics usage (Association of Plastics Manufacturers in Europe, APME). About 50% of Europe’s food is packed in plastic
packaging (British Plastics Federation, BPF).
Plastics have properties of strength and toughness. For example, polyethylene
terephthalate (PET) film has a mechanical strength similar to that of iron, but
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