Synthesis of Pinolenic Acid Enriched Triacylglycerol from Pine Nut Oil via a Two-step Consecutive Enzyme Reaction

Abstract

Pinolenic acid (PLA), Δ‐5,9,12‐octadecatrienoic acid-C18:3, is a plant origin polyunsaturated fatty acid and is contained abundantly in pine nut oil. PLA has several health benefits, such as the reduction of atherosclerosis, inflammation, and blood pressure. In addition, PLA may work as an appetite suppressant by increasing the effect of satiety hormones, such as cholecystokinin and glucagon-like peptide-1. The aim of this study was to synthesize PLA-enriched TAG from pine nut oil via a two-step lipase-catalyzed reaction, which is ethanolysis and esterification. In the first step, PLA was enriched up to ca. 42% as ethyl ester form, from 14% in pine nut oil by Lipozyme 435-catalyzed ethanolysis with an excess amount of ethanol. In the second step, PLA-enriched TAG was synthesized with glycerol and two different acyl donors, PLA-enriched fatty acid and PLA-enriched ethyl ester via Lipozyme 435-catalyzed esterification under vacuum condition. The TAG conversion and reaction rate with fatty acid form were significantly higher than those with ethyl ester form. Thus, the effect of temperature and vacuum on the synthesis of PLA-enriched TAG were investigated with fatty acid form as an acyl donor. The optimum temperature and vacuum were 60 oC and 5 torr, respectively. The TAG conversion of approximately 95% was achieved after 12 h under the optimum conditions. In addition, fatty acid compositions of TAG synthesized at different reaction times were also explored.