the conjugated fatty acid ester such that phosphate salts are precipitated and the precipitated phosphate salts are removed application_number US 48901704 A description fatty acid esters containing 16 18 carbon atoms and at least 2 double bonds in the fatty acid component and 1 to 5 carbon atoms in the alcohol component are preferably used in a particularly preferred embodiment the fatty acid esters used are linoleic acid esters containing 1 to 5 carbon atoms in the alcohol component of these fatty acid esters linoleic acid methyl ester and linoleic acid ethyl ester are particularly preferred oils containing linoleic acid selected from the group consisting of sunflower oil thistle oil soybean oil cottonseed oil peanut oil rapeseed oil and palm oil may also be used as starting product for the production of conjugated fatty acid esters in accordance with the invention after conversion of the free fatty acids into the esters with alcohols containing 1 to 5 carbon atoms in a preferred embodiment alkali metal alcoholates containing 1 to 10 carbon atoms are used as bases during the isomerization phase where phosphoric acid is added alkali metal phosphates precipitate from the reaction solution and can readily be removed the alcohol formed during the reaction of phosphoric acid with alkali metal alcoholates may readily be distilled off in vacuo accordingly no contaminated solvents so expensive to dispose of are formed in the production process particularly preferred bases are potassium.