prevention of contamination of food by the packaging intended to
protect it is the object of constant research and regulation.
variety of materials are currently used for food packaging. Any
substance which migrates from the packaging into the food is of concern
if it could be harmful to the consumer. Even if the migrating substance
is not potentially harmful it could have an adverse effect on the
flavour and acceptability of the food.
State Food Acts control the possibilities of such migration by general
provisions governing the sale of food: they contain provisions that no
person shall sell any article which is adulterated or falsely
described, which contains any matter foreign to the nature of the food
or which is packed or enclosed for sale in any manner contrary to any
provision of the Act or the Regulations.
Australian Food Standards Code, which complements the Food Acts, sets
maximum migration levels for three specific monomers, the "building
blocks" of plastics. These are vinyl chloride, acrylonitrile and
vinylidene chloride. They are singled out for special attention because
of their known potential toxicity. Modern manufacturing methods have
reduced monomer residues in food contact plastics to the point where
they are no longer measurable.
other packaging materials are used in contact with food including
paper, fibreboard, glass, tinplate, aluminium and various types of
plastics. Australian Standards, which are separate from food
regulations, are used to define compositional requirements of a number
of other plastics for food contact use. However these standards cover
only six of the common plastics used in food packages and refer to the
additives which may be used in their manufacture rather than setting
limits on migration. The selection and control of these additives has
been based on what is permitted in some overseas legislation.
United States of America and the European Community either have, or are
preparing, complex regulations to control migration from food packaging
materials. In some instances these regulations set maximum limits for
potentially harmful migrating substances. In other cases where
migration presents a minimal hazard, permitted additives may be listed
without specific limits being set. Some plastics contain a large number
of additives including antioxidants, stabilisers, antistatics and
plasticisers. These are included to improve the functional properties
of the plastics.
concern over migration?
Some of the
additives used in plastics are more likely to migrate than others. The
main concern in the past has been in connection with plasticisers which
are used to improve the flexibility of some packaging materials. They
are used in a range of plastics but particularly in polyvinyl chloride
(PVC) films. Since it was recognised that in many PVC food contact
situations these plasticisers would migrate, the plastics industry has
moved to reformulate various grades of "cling" films to reduce the
likelihood of plasticiser migration. There is no evidence that
concentrations of plasticiser found thus far in food constitute a risk
to human health, but unnecessary exposure to such contaminants must be
avoided. This is the background to the more complex regulations now
being developed internationally.
of plastic containers and films in cooking
tendency for plasticisers to migrate increases at higher temperatures,
only those plastics specifically designed for oven use are suitable for
cooking. While little confusion is likely to arise with the use of
plastics in conventional ovens, their safe use in microwave ovens is
more complex. Many plastic containers may appear to perform
satisfactorily in the microwave oven, but their migration levels at
high temperatures will not necessarily have been tested. This applies
particularly to those food containers used to package chilled or frozen
foods e.g. ice cream containers, which are not designed to be exposed
to high temperatures.
FOR THE USE OF PLASTICS IN MICROWAVE OVENS
- Use only
some packaging films may be labelled 'microwave-safe' care should be
taken to avoid direct contact with the food when using them to cover
containers or to reheat dinners on plates. Clean white absorbent
kitchen paper may be a preferable alternative to prevent spatter.
migration is more likely to occur into hot fatty foods, glass
containers are a suitable choice for heating these products.
are as yet no standards for claims such as "microwave safe"; if you are
in doubt as to the safety of such materials you should contact the
manufacturer for more details.
in microwave packaging
commercially prepared foods designed for the microwave have been
pre-cooked and frozen. These use relatively simple packaging systems
which while designed for microwave use, have no potential application
shelf-stable microwaveable foods have also appeared on supermarket
shelves. These involve more complex packaging systems which have been
specially designed for use at high temperatures. They are therefore
quite safe for microwave heating when manufacturers' instructions are
foods for the refrigerator
temperatures, including refrigeration, migration of plastic components
to a food may occur. This migration will be much slower than at higher
temperatures. While there is no evidence that plasticisers migrate into
even fatty products such as cheese at levels that pose a threat to
health, if you wish to avoid using a plastic wrap with a relatively
high plasticiser level, choose one which is clearly labelled
and board materials may transmit taint or odour to a food, plastics
have a much greater potential to do this. These taints may be residual
monomer e.g. styrene. This is probably the compound usually responsible
when consumers detect a 'plastic taste' in a food.
most food packaging is printed and a number of the components of the
ink may cause unpleasant flavours in food if manufacture of the
packaging material is not carefully controlled.
be remembered that many common plastics are not effective barriers to
strong odours. This can often be a problem when storing food in the
refrigerator. Odours from food such as garlic or onion can easily pass
through plastic film and taint other food.
plastics and paper
little work has been done to determine what chemical changes occur when
plastic and paper materials are recycled.
of in-house scrap materials has been practised by the packaging
industry for many years. Such materials present no potential hazard
because they have never been used as packaging.
the use of recycled packaging materials, other than metals and glass,
after the consumer has used them is potentially a problem because of
contamination from a variety of sources. Since there are no controls on
the treatment procedures or the uses to which these materials have been
put, there is no control over the type of contaminants which may be
adoption of a Code of Practice by the packaging industry would be the
most appropriate way to deal with the use of recycled materials in any
form of packaging. This would also require research to establish the
potential dangers, and provide means for their elimination.
inevitable that some recycled materials would not be acceptable for use
in many food packaging applications.
National Food Authority is monitoring discussions between CSIRO and
parts of the packaging industry on the potential application of
recycled packaging materials in the packaging of foods. The Authority,
through the food regulations, has the role of determining when and how
recycled materials could be used.
should be aware that recycled materials are second-hand. Products
packaged in recycled packaging materials should be labelled as such.
This is especially important with imported packaging materials and
foods packaged in imported materials. The public should be conscious
that there are potential problems especially since the European
Economic Community seems to have started exporting used packaging
materials to Developing Countries following the introduction of
regulations designed to reduce land fill demand in Europe.
situation is clarified it is advisable not to use recycled materials in
food contact situations.
potentially large number of substances that can migrate from packaging
into foods, comparatively few incidents occur which make the
food/packaging combination unsuitable. This is because the packaging
industry recognises the potential problems, and the selection of
packaging materials and the manufacturing processes are constantly
monitored and improved.