Kim_2018_J.Oleo.Sci_67_1435

delta5-Olefinic acids have been characterized in gymnosperm plants and have been reported to have several biological health benefits. delta5-Olefinic acids from pine nut oil were effectively concentrated by repeated lipase-catalyzed esterification. The pine nut oil contained three major delta5-olefinic acids, namely taxoleic acid (C18:2 delta5,9), pinolenic acid (C18:3 delta5,9,12), and sciadonic acid (C20:3 delta5,11,14). The fatty acids present in pine nut oil were selectively esterified with ethanol using Lipozyme RM IM from Rhizomucor miehei as a biocatalyst. The delta5-olefinic acids were concentrated in the unesterified fatty acid fraction. The optimum molar ratio of the substrates (fatty acid:ethanol), temperature, the enzyme loading, and the reaction time were 1:7, 25 degC, 5% of total substrate weight, and 6 h, respectively. There was no significant effect in the concentration of delta5-olefinic acids when water was added in the reaction mixture. The same protocol and optimum conditions were employed for two times repeated lipase-catalyzed esterifications. In first lipase-catalyzed esterification, the delta5-olefinic acids content in the pine nut oil increased from 17 mol% to 51 mol% with a yield of 40 mol%. In a second lipase-catalyzed esterification, with the delta5-olefinic acids-concentrated fatty acids obtained from the first reaction as the substrate, the delta5-olefinic acids content increased to 86 mol% with a yield of 15 mol%. Finally, a maximum delta5-olefinic acids content of ca. 96 mol% with a yield of 6 mol% was obtained via a third lipase-catalyzed esterification.