(57) A process for treating an unsaturated fatty oil to reduce its odour and/or colour and to increase its resistance to oxidative degradation with time, wherein said oil comprises an unsaturated ester of a higher fatty alcohol and a higher fatty acid or a triglyceride of an unsaturated higher fatty acid, the fatty acid or alcohol moiety being wholly or partially polyenic, which process comprises the following two steps in either order:

(a) subjecting the said oil, or the product of step (b), to selective hydrogenation to modify said fatty acid or alcohol moiety from polyenic to monoenic and simultaneously, to reduce any peroxides, aldehydes and ketones present therein; and

(b) dissolving the said oil, or the product of step (a), in a non-polar solvent and passing the solution through a column of an adsorbent for polar impurities, and then removing the soivent.