Comparison of linoleic and conjugated linoleic acids in enzymatic acidolysis of tristearin

The acyl incorporation and migration of linoleic and conjugated linoleic ac ids in enzymatic acidolysis were compared in a solvent-free system. Two sys tems were used in the Lipozyme RM IM-catalyzed acidolysis at 60C temperatur e and 5% by weight enzyme load (based on substrates). One included tristear in (SSS) and linoleic (L) or conjugated linoleic (cL) acids (1:6, mol/mol). The other was between tristearin and the mixture of linoleic and conjugate d linoleic acids (1:3:3, mol/mol/mol). Acyl incorporation and migration tog ether with triacylglycerol composition of the products were monitored with gas chromatography, pancreatic lipase hydrolysis, and high performance liqu id chromatography. Both acyl incorporation and migration of linoleic acid w ere faster than those of conjugated linoleic acid. At 5 h reaction, there w ere 13.0% LLL, 46.5% LSL, 27.7% LSS, and 5.6% SSS in the product for a syst em between tristearin and linoleic acid; whereas there were 2.4% cLcLcL, 10 .4% cLScL, 50.9% cLSS, and 36.2% SSS in the product for a system between tr istearin and conjugated linoleic acid. The results suggest that linoleic ac id was more reactive than conjugated linoleic acid in the enzymatic acidoly sis probably because of the rigid structure of the latter.