Canned
delicacies
Gautam
Bhattacharya lists the various canning technologies available, and explains
their respective advantages and disadvantages for packaging food products
Canning
of processed food products in tinplate containers was developed in the
early nineteenth century.
Containers made of tin free steel(TFS), aluminium and tin plate have
since been used for packaging of processed fruits, vegetables, meat,
fish and dairy products.
Technologies for canned products
The various kinds of technologies available for canning food products
are mentioned below:
Tin Free Steel
Developed in Japan, tin free steel is produced by chrome plating,
electro-mechanical chromate or chromate-phosphate treatment of cold
rolled steel sheets and is segregated on the basis of the coating. Chromated
sheets are generally non-solderable, therefore certain techniques have
been discovered in US, whereby the side seams of the cans are formed
by high pressure, forge welding or by using thermoplastic cement.
Cans are fabricated from TFS in such a way that the surface film remains
unpeeled after ordinary bending, curling, seaming and deepdrawing operations.
TFS cannot be soldered in the conventional can making line without the
removal of the surface film, but it can easily be stripped and seam-welded
by ordinary methods.
TFS cans, which contain sulphur, are used for packaging processed vegetables,
meat and fish products. They are also used for fabrication of general
line cans for packaging of dry food products, biscuits and edible oil.
Advantages of TFS
• The base layer of chromium acts as a corrosion barrier
• The superimposed layer of chrome-oxide prevents rusting and iron
taste pickup
• Chemical and thermal resistance and tolerance to high temperatures
• Ease of fabrication and resistance to great internal pressure
• Improved and more reliable double-seam.
Disadvantages of TFS
• Limitations for packaging of acid products
• Compulsory lacquering
• Not suitable for soldering, problems
in welding
Aluminium cans
Since their inception in 1818, aluminium cans are widely used in
Scandinavian countries.
Commercial grade aluminium contains very small quantities of silicon,
iron, titanium, copper and zinc as impurities and in chemical and food
industries, aluminium of 99.5 per cent purity is used.
Advantages
• Light weight and economical
• Versatile in terms of performance, aesthetic appeal and design
• Relatively easy to fabricate
• Accepts protective coatings, and is nontoxic, colourless and
does not have metallic taste
• Corrosion of the can does not produce coloured products.
Disadvantages
• Energy intensive production
• Cannot be soldered or flattened
• Cannot be sealed easily
• Needs beading and has greater tendency to bleach.
Tinplate
Tinplate is considered ideal for packaging
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