Bio-wrappers
M Shobita Rao, Dr Ramesh Chander and Dr Arun Sharma
tells you all there is to know about biodegradable food
packaging options
Can Mumbaikars imagine a more
dreaded date than 26/7? On July 26,
2005, the city witnessed
unprecedented havoc, chaos, loss of property
and life. With the deluge came the blame
game. Authorities said that it was neither the
drainage system nor the encroachment of
Mithi River, but the plastics bags that brought
Mumbai to its knees. Immediately, the sale of
food in plastic bags was banned. However, a
practical solution to the problem is needed.
What is the alternative of plastics? A range of
issues surrounding the development of any
food package must be considered before a
particular packaging
system
becomes a reality. To serve the end, Food
Technology Division has initiated
development of biodegradable packaging
materials, as food packaging and preservation
go hands in glove.
Food packaging requirements
Food, either in its raw or processed form is
highly perishable and therefore needs careful
technological intervention to preserve it
longer. This is where packaging comes into
picture. Deterioration in the sensory
attributes, nutritional content and safety of
food is caused principally by physical and
chemical changes in it during storage and by
microbial spoilage. The use of proper
packaging materials and methods to
minimise the food losses and provide
safe and wholesome food
products has
always
been the focus of the food packaging industry.
The packaging requirements of food are quite
complex. Unlike the inert packaged
commodities, food is often a live, dynamic
system and thus has specific packaging needs.
Product specific packaging
Food packaging is a challenging task, because
food materials are diverse and have specific
packaging requirements. The primary function
of a packaging material is to protect the
product from physical damage, microbial
deterioration and chemical changes. A
number of packaging materials meet most of
these requirements and they are being used,
either separately or in combination with other
materials. But every product has its own
specific need based on its chemical
composition, physiological condition and the
type of processing required
for final product.
Here are some examples:
Fresh fruits and vegetables
Fruits and vegetable continue to respire,
transpire and produce the ripening hormone
ethylene even after harvesting. Due to all
these processes, the concentrations of CO2,
O2, and water and ethylene change over
time, inside the storage packs. These changes
may have positive influence on the colour and
flavour of the products, but they may also
induce negative effects on texture, colour,
shelf life and nutritional quality. If the chosen
packaging material is impermeable to CO2,
O2 and water vapour, an anaerobic
environment inside the package will be
developed, thus leading to microbial
fermentation and product deterioration. If the
material is too permeable to water vapour, the
products will dry out and the atmosphere
inside will contribute to a reduced storage life.
An ideal packaging material will be the one,
which takes the respiration processes of
product into account so that the balance
inside the packaging is optimal, retains the
desirable odours and provides protection from
sunlight. Among the packaging materials used
for fruits and vegetables are monolayer PVC,
perforated thin LDPE, LLDPE, shrinkable film
and plastic netting.
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