Preparation of high purity docosahexaenoic acid from microalgae oil in a packed bed reactor via two-step lipase-catalysed esterification

• High purity docosahexaenoic acid (DHA) was prepared from microalgae oil.
• Lipase-catalysed esterification was employed for preparation of high purity DHA.
• The esterification was performed in packed bed reactor system.
• Finally, 100 wt% pure DHA was obtained from 42.5 wt% after two-step esterification.

Highly pure docosahexaenoic acid (DHA) was produced successfully in a packed bed reactor via the two-step lipase-catalysed esterification using the fatty acid from microalgae (from Crypthecodinium cohnii) and ethanol as substrates. Lipozyme RM IM from Rhizomucor miehei was employed as a biocatalyst. In the first step, a temperature of 40 °C, a molar ratio of 1:4 (fatty acid to ethanol), and a water content of 0.6 wt% (based on the total substrate weight) were selected as optimum conditions. A maximum DHA concentration of ca. 90 wt% was achieved in the fatty acid fraction with an 89 wt% yield after 15 min. In the second step, the fatty acids from the first step were used as the substrate and a recursive reaction was conducted using identical optimized conditions. Following this second step, a DHA concentration of 100 wt% was achieved in conjunction with an 83.2 wt% yield after 25 min.