The carton story
Times Food Processing Journal unravels the mysteries
of carton packaging
Impact-resistant, stackable and
economical, cartons have revolutionised
the trading and transport of milk. They
are eco-friendly, opaque, completely
recyclable and they help to conserve the
contents and resources. But not many people
know how the cartons are filled, whether they
manufactured by the filler or are they
delivered there in a finished state and
whether all cartons are identical.
Standardised, yet customised
Of course, cartons don't have to be
completely redesigned for each brand of milk.
Taking a modular approach, the carton
suppliers Tetra Pak, SIG Combibloc and
Elopak offer a variety of carton shapes and
sizes. A wide range of closure systems is also
available. Unlike the original version, virtually
none of today's practical drinks cartons are
sold without a resealable closure. But not all
cartons are the same. The way the layers are
arranged depend on the content; fruit juice
and milk have to be protected in different
ways and the taste of water is more
susceptible to change than that of apple
sauce, for example. In each case, the three
basic layers of the carton (cardboard,
aluminum and polyethylene) are combined to
produce the most effective outcome.
High-grade cardboard, which accounts
for 75 per cent of the entire packaging, gives
the carton its stability. The cardboard is
printed at a special cardboard factory, where
the closures and tearing joints are also
produced. For aseptically filled, germ-free
products such as long-life milk, the carton is
laminated with a layer of aluminum just six
µm thick. Polyethylene is employed as an
intermediate layer, resulting in 100 per cent
protection against air and light. Additional
polyethylene layers on the inside and outside
protect the carton from moisture. Most
important of all are the interior coating and
the longitudinal seam of the carton, as they
have to be completely leak-proof and suitable
for the contents in question. The finished
packaging material is then cut to size and
delivered to the filler, either in rolls or
stacked as sheets. The rolls are the same
width as an unfolded carton.
