Preparation of highly purified pinolenic acid from pine nut oil using a combination of enzymatic esterification and urea complexation

• Highly purified pinolenic acid (PLA) was prepared from pine nut oil in two steps.
• Firstly, PLA was enriched up to 43% from 13% by lipase-catalysed esterification.
• Selectivity of C. rugosa lipase against PLA was amplified with low temperature.
• Finally, 100% pure PLA was obtained from 43% after subsequent urea complexation.

Pinolenic acid (PLA) is a polyunsaturated fatty acid of plant origin. PLA has been successfully enriched according to a two-step process involving lipase-catalysed esterification and urea complexation. For the first step, the fatty acids present in pine nut oil were selectively esterified with lauryl alcohol using Candida rugosa lipase. Under the optimum conditions of 0.1% enzyme loading, 10% additional water, and 15 °C, PLA was enriched up to 43 mol% from an initial value of 13 mol% in the pine nut oil. For the second step, the PLA-enriched fraction from the first step was subjected to a urea complexation process. In this way, PLA enrichments with purities greater than 95 mol% were obtained at urea to fatty acid ratios greater than 3:1 (wt/wt), and 100% pure PLA was produced at a urea to fatty acid ratio of 5:1 with an 8.7 mol% yield.