DEGUMMING AND BLEACHING: EFFECT ON SELECTED CONSTITUENTS OF PALM OIL

摘要

Degumming and bleaching arc essential processes in palm oil refining. The purpose is the removal of gums, trace metals, pigments, peroxides, oxidation products and other breakdown products in the crude oil by adsorption on the active surface of the bleaching earth to improve colour and stability of the final oil. This paper aims to study the effect of degumming and bleaching using neutral and acid-activated clays to achieve the aforementioned objectives. It was found that valuable palm minor components, i.e. [tocols (tocopherol and tocotrienols) were retained; no significant changes occurred in the total phytosterols, squalene, composition of acylglycerols (i.e. mono-, di- and triacylglycerols)] and free fatty acids by using both acid-activated and neutral clays up to 1.0%. However, acid-activated clay reduced the carotenes content. Both clays gave markedly improved oxidative stability with induction period > 30 hr at 120℃. Impurities such as pro-oxidant iron,, copper and phosphorus were reduced by both clays. The bleaching effect of neutral clay was relatively poor compared to acid-activated clay in the removal of unwanted compounds.