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< prev - next > Food processing Packaging and bottling KnO 100270_Packaging_materials_for_foods (Printable PDF)
Packaging materials for Foods
Practical Action
re-useable; they are rigid, to allow stacking without
damage; and unlike metal cans, they are transparent
to display the contents. The main disadvantages of
glass are: the higher weight than most other types of
packaging, which incurs higher transport costs;
containers are easily broken, especially when
transported over rough roads; they have more variable
dimensions than metal or plastic containers; and there
are potentially serious hazards from glass splinters or
fragments that can contaminate foods (see Technical
Brief: Packaging Foods in Glass). Glass containers are
still widely used for foods such as juices, wines, beers,
pickles/chutneys and jams (Fig 3.), especially in
countries that have a glass-making factory, but their
disadvantages and the high cost for imported
containers in other places mean that they are steadily
being replaced by plastic containers.
Paper and cardboard
Paper and boards are made from wood pulp and
additives are mixed into the pulp to give particular
properties to the packaging, including:
Fillers such as china clay, to increase the
Fig. 3. Glass jars used by a small-
brightness of paper and improve surface
scale jam maker
smoothness and printability.
(Photo: Peter Fellows)
Binders, including starches, vegetable gums, and
synthetic resins to improve the strength.
Resin or wax sizing agents to reduce penetration by water or printing inks.
Pigments to colour the paper and other chemicals to assist in the manufacturing process.
Different types of paper are used to wrap foods: 'sulphate' paper is strong and used for single- or
multi-walled paper sacks for flour, sugar, fruits and vegetables; 'Sulphite' paper is lighter and
weaker and is used for grocery bags and sweet wrappers, as an inner liner for plastic biscuit
wrappers and laminated with plastic films. Greaseproof paper is sulphite paper made resistant to
oils and fats, and used to wrap meat and dairy products. ‘Glassine’ is a greaseproof sulphite
paper that is given a high gloss to make it resistant to water when dry, but it loses its resistance
once it becomes wet. Tissue paper is a soft paper used for example to protect fruits against dust
and bruising. Papers are also treated with wax to provide a moisture barrier and allow the paper
to be heat sealed. Wax coatings are easily damaged and the wax is therefore laminated between
layers of paper and/or polyethylene when used for bread wrappers and inner liners for cereal
‘Paperboard’ is a term that includes boxboard, chipboard and corrugated or solid fibreboards.
Typically, paperboard has the following structure:
1. A top layer of white material to give surface strength and printability.
2. Middle layers of grey/brown lower grade material.
3. An under-layer of white material to stop the colour of the middle layer showing through.
4. A back layer if strength or printability are required.
All layers are glued together with adhesive.
White board is suitable for contact with foods and is often coated with wax or laminated with
plastic to make it heat sealable. It is used for ice cream, chocolate and frozen food
cartons. Chipboard is made from recycled paper and is used for example as the outer cartons for
tea or cereals but not in contact with foods. It may be lined with white board to improve the
appearance and strength. Other types include moulded paperboard trays for eggs, fruit, meat or
fish or for egg cartons.
Small paperboard tubs or cans are used for snackfoods, confectionery, nuts, salt, cocoa powder
and spices. Larger drums are used as a cheaper alternative to metal drums for powders and other