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Milk is a largely perishable product that requires
to be delivered to the consumers in a safe condition and manner.
Regions like India, China, Europe and North America need more than
30 million litres of milk to be distributed every year. Each of
these regions has different distribution systems.
The North American consumers prefer fresh milk
that is pasteurized at about 75 degree C for 30-40 seconds so that
all bacteria are destroyed. Such pasteurized milk has a shelf life
of 4-7 days. The milk is distributed through supermarkets and grocery
stores. The packaging of such milk is done in HDPE monolayer containers
of sizes ranging from 1-4 litres. The packaging does not require
barrier properties due to a low shelf life, though at the same time,
sturdy rigid packaging is required to handle 4-litre package of
milk.
The European market has chosen UHT (Ultra High
Treatment) milk that is heated at 135 degree C for about 20 seconds
to provide a long shelf life of 6 months. The packaging of UHT requires
better barrier properties to survive this long shelf life. Instead
of using HDPE mono-layer containers, carton packs with Polyethylene
coating is selected on account of better barrier properties. The
carton is usually available in 1 litre size. To meet the weekly
requirement, each of the 1 litre carton packing is collated with
shrink packing. HDPE multi layer containers can also meet the barrier
properties and therefore can be used for UHT milk. The packaging
and distribution cost would be the selection criteria for these
two types of packaging.
On the other hand, India has chosen flexible pouches
made from LDPE/LLDPE for pasteurized milk. The distribution of milk
is usually by hand delivery to the consumers at their houses, mainly
due to relatively lower labour cost. It is estimated that almost
50KT of PE is being consumed for milk packaging. The consumption
figure could significantly grow much higher if entire milk consumed
in India is distributed in such a manner. There is also another
type of milk called Sterilized Milk, wherein milk is heated at 120
degree C for more than 30 minutes. For the sterilized milk, packaging
requires to withstand the heat treatment. Due to complete sterile
packing, such packaging does not need barrier properties although
the sterilsed milk is expected to give a shelf life of about 9 months
compared to 6 months for UHT milk. While glass bottles can be used
for sterilized milk, they are not chosen because of overall higher
cost and the hassle of recovering them for consumers for multi usage.
PET containers are often selected for value added milk products
because of their aesthetic values. However, they cannot be used
for UHT milk due to inadequate barrier properties.
Polyethylene, whether it is HDPE for rigid container
or LDPE as coating to the carton or as film for the flexible packaging
are the most chosen material for milk packaging.
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