Study on Preparation of Conjugated Linoleic Acids with Alkali Catalyst from Natural Unsaturated Fatty Acid Methyl Esters

Ma Lin, Fan Ye, Fang Yun* (MOE Key Laboratory of Food Colloids and Biotechnology, School of Chemical & Material Engineering, Jiangnan University, Wuxi, Jiangsu 214122, China) Abstract: 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. CLAs have been widely applied in food, pharmaceutical, health care, cosmetics and many other fields, due to its anticarcinogenesis and anti-atherosclerosis, participating in fat metabolism and enhancing immune function. 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, alkalior metal-catalyzed isomerization of linoleic acid, enzyme-catalyzed transformation and microorganism fermentation. In this paper, breaking traditional synthetic methods, synthesis of CLAs with methyl linoleate as starting material has been investigated. The synthesized CLAs 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 C for 4 h.