Fat or fit?
Ever wondered how fats and oils can be healthy?
Prakash N Chawla explains the process
Oils and fats are not only important as
a source of nutrition but for
enhancing the taste of food. While
the most commonly produced oils in the
world are that of palm and soyabean, other
oils like coconut, sunflower, rapeseed,
safflower, peanut, flaxseed and olive too have
their own importance. Every oil has its own
distinct fatty acid composition, which in turn,
gives the oil widely different nutritional and
functional properties. Modern technology
helps us to process these oils for specific
nutritional or functional properties for use in
the food industry. This class of products are
usually referred to as speciality oils and fats.
Processing of oils
Processing of oils and fats for speciality
application require a different set of skills than
conventional oil processing. Production
flexibility and consistency of quality are the
key requirements since a variety of raw
materials and finished products require
storage and processing in smaller batches.
Similarly, quality assurance system ensuring
conformance is necessary, as the products
have to be processed for very stringent
specifications. Custom made products too
require care, as their batch sizes are minimal.
Different stages in oil processing (oils obtained
from oilseeds) are further outlined below:
• Expelling
The mechanical pressing consists of passing
the pre-treated seeds into a screw press; oil
oozes due to the developing high pressure and
gets collected in a tray provided at the bottom
of the press. This oil is then filtered.
• Extraction
Solvent extraction is employed in case of
oilseeds and pre-pressed cakes, which have
lower percentage of oil in them. A typical
solvent extraction unit consists of physical
removal of oil from the seed using a solvent,
which is usually hexane. The solvent is then
distilled off from the oil-solvent mixture.
• Refining
This step refers to removal of impurities from
the oil. Oil contains free fatty acid gummy
matter, colour pigments, odiferous
compounds, sterols, phospholipids etc. The
oils are further refined by neutralisation,
bleaching and deodourisation.
• Oil modification processes
To extend the application in fat-based food
products, oils undergo a chemical and physical
modification. The best-known modification
processes applied today in the edible oil
industry are listed below.
• Hydrogenation
The oil is infused with hydrogen in the
presence of nickel catalyst. The hydrogen
converts the fatty acids from unsaturated
to saturated, lowering the iodine value and
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