Lipase-catalyzed acidolysis of olive oil with Echium oil stearidonic acid: Optimization by response surface methodology

In this study, our aim was to enrich olive oil with stearidonic acid (SDA) together with polyunsaturated fatty acids (PUFA) by lipase-catalyzed acidolysis using olive oil (OO) and free fatty acids of Echium oil, in the presence of Lipozyme^® TL IM. The reaction conditions were optimized by using response surface methodology. A three-factor, five level central composite circumscribed designs was used to generate the design points. The factors chosen were: substrate molar ratio (S_r, 4-6 mol/mol), reaction temperature (T, 55-65 °C), and reaction time (t, 6-9 h). Targeted incorporation (5 %) of SDA into OO was achieved at substrate molar ratio of 6 mol/mol, 55 °C, and 8.4 h. Model verification performed under these conditions for mg- and g-scale production yielded SDA contents of 4.9 and 4.8 %, respectively. Moreover, it was observed that the structured lipid (SL) obtained under optimum conditions contained approximately 42 % oleic acid and 43 % PUFA including linoleic acid, α-linolenic acid, and γ-linolenic acid. Omega-6/omega-3 fatty acid ratio of SLs was 0.7. Analysis of oxidative properties resulted in lower oxidative stability of SL than unmodified OO. This type of SL containing SDA and other PUFA is believed to be beneficial for human health.