Packaging materials

Packs can be made of glass, plastic or carton.

i) Glass Packs

Advantages

•  No environmental contamination during destruction of glass.
•  No adverse effect on the product.
•  No odour and taste
•  Resistance against moisture
•  No gas diffusion

 Disadvantages

•  Higher weight than plastic packs or carton packs, being important for transport.At present investigations have been done to reduce the weight of glass containers as much as possible.
•  Since glass containers are usually returnable packs, additional room is needed for storage.
•  Additional work for cleaning of returned bottles.
•  Glass containers give a bad protection against light-induced flavour changes.This can be reduced through the corresponding colouring of glass (e.g. brown bottles).
•  Impossible to print (sticking of advertising labels is possible).
•  Larger space is required for sweepings.
•  No tight closure (but protects efficiently against external contamination).

 ii) Plastic Packs

Plastic packs enjoy today a great popularity. They consist of polyvinylchloride (PVC), polyvinylchloride/ polyvinylidenchloride (PVC/ PVDC), polystyrene (PS), laminated foils with sarane, or a low pressure polyethylene (LPE).The PVC and PVDC have a relatively low permeability to water vapour, oxygen,nitrogen and carbon dioxide. In contrast to this, polystyrene and polyethylene demonstrate a high permeability to oxygen, nitrogen and carbon dioxide. The oxygentight properties of PVC and PVDC foils make them very suitable materials for packaging.

a) Pre-Fabricated Cups (Ready-Made Cups)

The pre-fabricated cups are usually used as packs. The main advantage is a diversification of packaging the product, e.g. shape, printing and other market requirements.Another advantage is an equal quality of cups. The ready-made cups are tested for weight, electrostatic properties, strength, homogeneity, etc. and subsequently packaged into dust-tight carton boxes. A disadvantage of these cups may be their liability to airborne contamination by undesirable organisms.

(b) Thermoformed Cups

The thermoformed cups are produced in the dairy by using specially designed equipment for automatic cup forming, filling, sealing and punching.It is interesting to make a comparison between the pre-fabricated cups and the thermoformed cups from the practical point of view. This is shown below.

c) Automatic Plastic Cup Forming, Filling, Sealing and Punching Machines

Advantages are:

•  Lower costs of the packaging materials.
•  Firm blown and splinter-proof materials.
•  Lower labour costs.
•  Gas-tight and light impermeable packs can be obtained by using complex foils.
•  Multi packs are possible.
•  Small store volume for the packaging foils.
•  Heat treatment of the plastic foils and AI lids.
•  Aseptic packaging is developed.

 Disadvantages are:

•  Increased liability to interruption in running of a machine.
•  Higher requirements for service personnel.
•  Higher costs for maintenance and repair.
•  Limitations in the shape of cups.
•  Greater investment.
•  Small pressure load on cups.
•  Waste of the packaging foils and lids.
•  Higher energy costs.

 d) Automatic Plastic Cup Filling and Capping Machine

Advantages are:

•  High safety in operation of a machine.
•  Low liability to interruption in running of a machine.
•  Low costs for maintenance.
•  Low energy costs.
•  Higher pressure load on cups.
•  Changing cups to different size and shape is possible.
•  Gas-tight and high impermeable packs can be installed.
•  No waste.
•  Aseptic packaging is developed.

 Disadvantages are:

•  Higher material costs
•  Larger store volumes required for the stock of cups.
•  Certain store volumes required for the stock of cups.
•  Certain machines require a separate punching unit.
•  Increased labour expenses

 iii) Waxed Carton Packs

 Carton packs coated with paraffin have been somewhat displaced by plastic packs. Carton packs have the following advantages:

•   Can be very nicely printed.
•  They have light-weight
•  Not-returnable.
•  No problems in the utilization of sweepings.

 Disadvantages are:

•  Discolouration of the internal part of containers caused by certain fruit base (e.g. partial blue discolouration with bilberry yoghurt).
•  Eventual occurrence of the paper taste.

 iv) Combined Materials and Laminated Foils

The favorable price, weight and stability of a paper can be combined with advantages of other packaging materials in order to obtain a material with new characteristics. Many packs developed at present have been based on the combination of papers and cartons with AI foils and plastic foils.Suitable combinations of different plastic foils may be interesting, too. Such laminated foils have the following advantages: gas and moisture tight, the possibility for hot filling of yoghurt after pasteurization, the maintenance of increased storage life of the product, a high structural strength of pack, special protection against light, etc.