New developments in the bleaching of palm oil

The use of activated bleaching earth (clay)in the processing of oils and fats has a long and successful history.

Bleaching earths have gradually andsteadily improved in quality so that with reasonably good crude palm oil,addition of about 1% enables the desired final colour limit of 3 RED (5.25 inchLovibond cell) to be reached every time.But the performance of a bleaching earthcannot be assessed on colour considerations alone because the removal ofphosphatides and trace metals is also very important in ensuring maximumstability to oxidation and resistance to flavour deterioration.

Now new materials are challenging theposition of bleaching earth e.g. the development of silica hydrogel which, whenused to replace part of the bleaching earth, lead to equally good colour valuesin the finished oil, and also much better removal of phosphatides.Thus, 0.3% hydrogel plus 0.6% bleachingearth gives better removal of trace metals and gums than 1.3% bleaching earthalone.