The classical chemical synthesis of CLA triglycerides starting from the free fatty acids and glycerol leads to the formation of additional CLA isomers not suited for applications in the field of human nutrition. Greener methods for a more selective production of CLA triglycerides under gentle reaction conditions were evaluated [1][2][3][4]. The enzymatic synthesis works well under vacuum conditions with a clear preference for free fatty acids as substrates in comparison to alkyl esters. The reaction velocity was enhanced significantly by the addition of basic additives into the reaction mixture. A combined one pot synthesis was designed starting from ethyl esters consisting of an enzymatic ester hydrolysis followed by a re-synthesis of the fatty acids with glycerol. Additionally, a new chemical interesterification reaction with triacetin (triacetyl glyceride) as synthon was developed, which avoids the formation of undesired CLA isomers.

, activated carbon, titanium silicalite TS-1, were prepared and used for the isomerization of linoleic acid (cis-9,cis-12-octadecadienoic acid) to conjugated linoleic acids (CLA) in the presence of hydrogen at 165°C in a batch reactor. The best results were obtained using a catalyst with 2 wt % Au on TS-1, which exhibits a high selectivity (78 %) towards CLA. The two biologically active target CLA isomers, i.e., cis-9,trans-11-CLA and trans-10,cis-12-CLA, were the main products. During the isomerization of linoleic acid to CLA, consecutive reactions also took place. These were the hydrogenation of linoleic acid and CLA to monounsaturated octadecenoic acids and the further hydrogenation of monounsaturated acids to stearic acid. Thus, gold catalysts are capable of isomerizing linoleic acid to CLA and hydrogenating their double bonds to an extent that depends on the Au catalyst used.

No abstract

No abstract