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Production process
Refining
The refining is composed of several successive stages :
- Neutralization : the free fatty
acids are eliminated by saponification and centrifugation
(chemical refining) or by distillation (physical
refining)
- Bleaching : The pigments responsible
for the colour are eliminated by the use of bleaching
clays (bentonites) that are later removed by the
filtration.
During this stage, it is possible to add active carbons
in the oil to capture and eliminate the major part
of the contaminants: dioxins, PCBS and PAH…
These active carbons are lately removed by the filtration.
- Deodorization : It is vacuum carried
out inside a reactor at about 200 °C with injection
of water steam. The steam passing through the oil
carries away the volatile substances responsible
for the odours. It enables also to reduce significantly
the traces of pesticides.
Winterisation
Winterisation is a technical term which means cold
filtering of the oils.
The purpose of winterisation is manly to make an oil
limpid by removing the waxes or fats naturally contained.
The oil is slowly cooled down to obtain a homogeneous
cristallisation of waxes and fats. It is then filtered
through cloths that retain these waxes or fats.
The efficiency of a winterisation process can be measured
by one of the following tests : cold test, cloud point,
congeal point, melting point or drop point. |
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