Enzyme-assisted synthesis of structured lipids containing long-chain omega-3 and omega-6 polyunsaturated fatty acids

• Main Author: Senanayake, S. P. J. Namal
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2000
• Subjects: Rugosa; Antarc*; Antarctica
• Online Access: https://research.library.mun.ca/9148/; https://research.library.mun.ca/9148/1/Senanayake_SPJanakaNamal.pdf

Lipase-catalyzed acidolysis of borage (Borago officinalis L.) and evening primrose (Oenothera biennis L.) oils with long-chain ω3-polyunsaturated fatty acids (LCω3-PUFA), namely docosahexaenoic acid (DHA) and/or eicosapentaenoic acid (EPA), in organic solvents was studied. Six microbial lipases from Candida antarctica, Mucor miehei, Pseudomonas sp., Aspergillus niger, Candida rugosa and Thermomyces lanuginosus were initially used as biocatalysts for the acidolysis reaction. Among the enzymes tested, an immobilized lipase, Novozym-435 from Candida antarctica showed the highest degree of DHA incorporation (25.8-28.7%, after 24 h) in borage oil (BO) and evening primrose oil (EPO). However, the maximum incorporation of EPA (28.7-30.7%, after 24 h) in both oils was achieved with lipase PS-30 from Pseudomonas sp. In another study, incorporation of EPA+DHA into BO and EPO was carried out by first screening of lipases listed above; lipase PS-30 from Pseudomonas sp. was the most efficient enzyme examined (31.7-32.7% EPA+DHA incorporation, after 24 h). -- Effects of variation of reaction parameters, namely enzyme load, temperature, time course, mole ratio of substrates and type of organic solvents were monitored for the most effective enzymes, those from Candida antarctica and Pseudomonas sp., as the biocatalysts of choice. Incorporation of DHA and/or EPA increased significantly (p ≤ 0.05) with increasing the amount of enzyme. As the incubation time progressed, incorporation of these fatty acids was also increased, similar to that observed when the temperature and mole ratio of substrates increased. The highest DHA (37.4-39.7%) or EPA (37.4-39.9%) incorporation occurred at a mole ratio of 1:3 (oil/ DHA or EPA). However, maximum incorporation of EPA+DHA (54-57.5%) occurred at a mole ratio of 1:2:2 (oil/EPA/DHA) and then remained constant between mole ratios of 1:2:2 and 1:3:3. Among solvents examined, n-hexane served best in giving rise to 25.5-27.4% DHA, 25.2-26.8% EPA and 27.8-33.3% EPA+DHA incorporation in the oils. ...