Processing of Vegetable Oils – Loss of Minor Components: A Review.

The demand for vegetable oils and fats in India during
2016 was about 216.6 lakh tons while it produced
about 72.5 lakh tons during the same period. About
146.1 lakh tonnes of vegetable oil was imported
during 2016-17 in to the country to meet the demand.
Vegetable oils are produced mainly by two methods,
viz., expeller pressing and solvent extraction of the
oilseeds. Expeller pressed vegetable oils are nearly
natural and those produced by solvent extraction
undergo further processing to get refined oils which
are devoid of major amounts of natural components
such as colour, flavour / aroma and other oil soluble
substances found in the expeller oils. Expeller
pressed vegetable oils retain natural aroma of the
oilseed, contain pigments and various other
constituents which have biological effects such
as antioxidant, anti-aging, anticancer,
hypocholesterolemic, hypotriglyceridemic, and many
others. While those prepared by solvent extraction
undergo processing steps such as degumming,
dewaxing, bleaching, alkali refining, distillation /
steam stripping of free fatty acids at high
temperatures and the deodourization to obtain a
colourless, odourless and bland vegetable vegetable
oil leaving behind waste sludges, DOD etc. During
these processing steps many natural substances
such as phospholipids, glycolipids, waxes,
odouriferous substances, colouring pigments are
removed intentionally to provide a colourless,
odourless refined oil while phytosterols,
phytostanols, squalene, tocopherols, tocotrienols are
all removed to varying extents due to processing
conditions employed, hence depriving the consumer
of the health benefits these would provide in the long
run. Therefore, there is a need to develop unrefined
vegetable oils with very low free fatty acids level and
with minimal processing and retaining all the natural
materials which are removed either intentionally or
unintentionally to provide the health benefits of the
lost nutrients to the consumer.