A
grain of truth
Gautam
K Bhattacharya delves into the packaging options available for various
cereal-based foods and outlines advantages of each
India
is facing a major challenge in terms of producing enough cereals to
feed its entire population. There is a dire need to ensure that these
cereals, produced in huge quantities, are stored properly and transported
to various levels of the supply chain, so that spoilage is minimum.
In this regard, cereals and its derivative products can be grouped as:
• Milled grain products
• Processed cereal and pulse products
• Cereal based convenience foods
Milled grain products
Wheat being one of the most generously produced cereals in India,
its derivatives – either whole wheat flour (atta) or milled products
like maida, sooji and besan – form the bulk of this category. These
products are prone to deteriorative changes such as rancidity, microbial
spoilage, insect infestation and so on. It is important to ensure that
moisture absorption level for most of the milled products does not exceed
12 per cent, the Critical Moisture Content of most cereals.
Above this critical value, hydrolysis of the fat present in these products
happens much faster, thereby leading to faster spoilage. Retail packs
used for packaging milled grain products are usually in the form of
pouches or pillow packs. These also serve the purpose of converting
a traditional commodity like atta to a recognised brand.
The
most commonly used flexible packing materials are:
Low density polyethylene film (LDPE): This is the most
commonly used packaging material because of its easy availability and
low cost. It acts as a moderately good barrier for water and water vapour.
LDPE is not very effective in preventing the transmission of various
gases. On the other hand it is heat-sealable, easily printable and has
moderately good tensile strength, bursting strength, impact resistance
and tear strength.
Linear Low Density Polyethylene (LLDPE): As compared to LDPE
film, LLDPE has better tensile strength, higher puncture resistance
and stiffness. It is approximately 50 per cent better in all the above-mentioned
factors than the LDPE film. Owing to these advantages, LLDPE films are
fast replacing LDPE films for retail packaging of milled grain products.
High Molecular High Density Polyethylene (HMHDPE): HMHDPE is
characterised by its high mechanical strength and toughness. The material
is used in very low thickness for packaging. It is mostly translucent
and can be modified by the addition of pigments.
Co-extruded films: Fat seepage is a common problem in LDPE /
LLDPE packs. Using a coextruded film, which makes LDPE / LLDPE more
effective, can prevent this. Such structures become more effective when
the structure is formed using metallocene resin. This helps in producing
a good seal, which is critical for powdery products like atta.
Poly Propylene (PP): PP finds wide application in packaging products
like atta and sooji.
Its characteristics are:
• High stiffness and high tensile strength
and usage possibility of lower thickness films
• Very low density and thereby higher yield
• Low moisture vapour transmission rate.
Biauxially Oriented Poly Propylene (BOPP):
BOPP is a better packaging option than other materials. It acts as an
extremely strong barrier for moisture transmission. It has high transparency
and gloss, has higher strength than PP and can be made heatsealable.
It can also be reverse printed and laminated easily as a multilayer
barrier material. The thickness range of BOPP, used as a layer for cereal
packaging, should ideally be 12-40 micron.
Laminates: A multilayer film laminate offers better protection
than a monolayer film. Typical structures that are in use for cereal
products are BOPP / LDPE or Polyethylene Terepthalate (PET) / LDPE.
There are many advantages of using a laminate structure:
• Odour penetration: In a retail outlet,
cereal products are stacked along with many strong smelling commodities
and hence odour barrier is important. Laminated structures acts as a
strong barrier against the penetration of such odours
• Printing ease: PET / BOPP laminates
can easily be reverse printed, ensuring not only a better finish of
the pack in terms of scuff proof surface, but also that foods do not
get contaminated directly by getting exposed to solvents of ink used
in printing the same. Secondary packs: For a successful retail
pack, its imperative that due consideration is given towards the secondary
package. For the packing of most of these cereal products, High Density
Polyethylene (HDPE) / PP woven sacks are most commonly used. Bulk packs
and corrugated board boxes are the most commonly used secondary packs.
Processed cereal and pulse products
There is an increasing demand for processed cereal
and pulse products like noodles and vermicelli. These are highly perishable
in nature and are prone to softening and microbial spoilage, if appropriate
moisture protection is not ensured.
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