DHA Concentration and Purification from the Marine Heterotrophic Microalga Crypthecodinium cohnii CCMP 316 by Winterization and Urea Complexation

Ana Mendes, Teresa Lopes da Silva* and Alberto Reis

Instituto Nacional de Engenharia, Tecnologia e Inovação, Departamento de Biotecnologia, Unidade de Bioengenharia e Bioprocessos, Estrada do Paço do Lumiar 22, P-1649-038 Lisboa, Portugal

Article history:
Received January 9, 2006
Accepted April 6, 2006

Key words:
DHA, PUFAs, Crypthecodinium cohnii, winterization, urea complexation

Summary:
A simple and inexpensive procedure involving saponification and methylation in wet biomass, winterization and urea complexation in a sequential way has been developed in order to concentrate docosahexaenoic acid (DHA) from Crypthecodinium cohnii CCMP 316 biomass. Different urea/fatty acid ratios and crystallization temperatures were tested in the urea complexation method. ANOVA test revealed that, in the studied range, the temperature had the most significant effect on the DHA concentration. The highest DHA fraction (99.2 % of total fatty acids) was found at the urea/fatty acid ratio of 3.5 at the crystallization temperatures of 4 and 8 °C. The highest DHA recovery (49.9 %) was observed at 24 °C at the urea/fatty acid ratio of 4.0, corresponding to 89.4 % DHA of total fatty acids. Considering the high proportions of DHA obtained in the non-urea complexing fractions, the current procedure was an appropriate way to concentrate and purify DHA from C. cohnii.

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