Study On Preparation of Conjugated Linoleic Acids With Alkali Catalyst From Natural Unsaturated Fatty Acid Methyl Esters

Conjugated linoleic acids (CLAs) are a group of positional and geometrical isomers of conjugated octadecadienoic acids, which are naturally unsaturated fatty acid with conjugated double bonds. As is shown to inhibit carcinogenesis and atherosclerosis, participate in fat metabolism and enhance immune function, CLAs have been widely applied in food, pharmaceutical, health care, cosmetics and many other fields. Chemical modification methods, therefore, to prepare CLAs from natural unsaturated fatty acids have attracted more and more attention nowadays, which mainly include dehydration of ricinoleic acid in castor oil, alkali- or metal-catalyzed isomerization of linoleic acid, enzyme-catalyzed transformation and microorganism fermentation. In this paper, breaking traditional synthetic methods, it studied the synthesis of CLAs with methyl linoleate as starting material. The CLAs after synthesis were characterized by GC and UV-Vis. The content of CLAs reached 90 % with sodium hydroxide as catalyst, which concentration was 20 % compared with methyl linoleate, at 170 ^oC for 4 h.