US 4,792,418 AGranted

Method of extraction and purification of polyunsaturated fatty acids from natural sources

AssigneeCentury Laboratories, Inc.

InventorsDavid Rubin, Elyiahu J. Rubin

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Abstract

To extract and purify of polyunsaturated fatty acids, particularly EPA and DHA, without cis-trans conversion, from naturally occurring oils, such as marine animal oil and various vegetable oils a mixture of free fatty acids is first extracted from the oil. The resulting mixture of pure fatty acids is then subjected to separation by means of urea complexing to remove saturated fatty acids and most mono-unsaturated fatty acids. Remaining solvent and urea are then removed from the filtrate which is then subjected to low temperature fractional crystallization in the presence of an organic solvent such as acetone. Substantially pure polyunsaturated fatty acids, especially EPA and DHA, can be separately precipitated by reducing the temperature of the filtrate in two steps. Alternatively, the volume of the filtrate is reduced in two steps and cooled to form precipitates, which are removed. The final product is a mixture of substantially pure DHA and EPA.

Claims33

Dependent claims

A method for separating a substantially pure mixture of (all-Z)-5,8,11,14,17-eicosapentaenoic acid (EPA) and (all-Z)-4,7,10,13,16,19-docosahexaenoic acid (DHA) from marine animal oil, using only reaction conditions sufficiently mild to avoid degradation of the EPA and DHA, consisting essentially of the steps of:

(1) extracting a mixture of polyunsaturated free fatty acids, or methyl or ethyl esters thereof from the oil,
(2) mixing said fatty acids or esters with urea and a polar organic solvent, the solvent being present in a quantity sufficient to dissolve the urea and the fatty acids or esters, and the urea being present in a quantity sufficient to form a coordination complex with all of the fatty acids or esters capable of being complexed by the urea;
(3) removing the precipitate which forms after said mixing step and recovering the filtrate;
(4) removing remaining solvent and urea from the filtrate to obtain pure fatty acids or esters;
(5) forming a solution by dissolving the pure fatty acids or esters in an organic solvent;
(6) gradually cooling the solution until a first precipitate forms and removing said first precipitate;
(7) removing sufficient solvent from the filtrate remaining after the precipitate is removed to substantially reduce the volume and increase the concentration of the solution;
(8) gradually cooling the solution until a second precipitate forms and removing said second precipitate;
(9) removing sufficient solvent from the filtrate remaining after the second precipitate is removed to substantially reduce the volume and increase the concentration of the solution;
(10) gradually cooling the filtrate until a separate liquid or solid phase forms and removing said separate phase;
and
(11) retaining the remaining liquid phase containing a mixture of substantially pure EPA and DHA.

9 more elements

A method for separating substantially pure (all-Z)-5,8,11,14,17-eicosapentaenoic acid (EPA) from marine animal oil, using only reaction conditions sufficiently mild to avoid degradation of the EPA, consisting essentially of the steps of:

(1) extracting a mixture of polyunsaturated free fatty acids, or methyl or ethyl esters thereof, from the oil;
(2) mixing said fatty acids or esters with urea and a polar organic solvent, the solvent being present in a quantity sufficient to dissolve the urea and the fatty acids or esters, and the urea being present in a quantity sufficient to form a corrdination complex with all of the fatty acids or esters capable of being complexed by the urea;
(3) removing the precipitate which forms after said mixing step and recovering the filtrate;
(4) removing remaining solvent and urea from the filtrate to obtain pure fatty acids or esters;
(5) forming a solution by dissolving the pure fatty acids or esters in an organic solvent which remains in the liquid state below the temperature at which EPA prcipitates therefrom;
(6) gradually cooling and removing any new solid or liquid phases which separate from the solution during the cooling process;
and
(7) retaining the phase containing substantially pure EPA.

5 more elements

A method for separating substantially pure (all-Z)-4,7,10,13,16,19-docosahexaenoic acid (DHA) from marine animal oil, using only reaction conditions sufficiently mild to avoid degradation of the DHA, consisting essentially of the steps of:

(1) extracting a mixture of polyunsaturated free fatty acids, or methyl or ethyl esters thereof, from the oil;
(2) mixing said fatty acids or esters with urea and a polar organic solvent, the solvent being present in a quantity sufficient to dissolve the urea and the fatty acids or esters, and the urea being present in a quantity sufficient to form a coordiantion complex with all of the fatty acids or esters capable of being complexed by the urea;
(3) removing the precipitate which forms after said mixing step and recovering the filtrate;
(4) removing remaining solvent and urea from the filtrate to obtain pure fatty acids or esters;
(5) forming a solution by dissolving the pure fatty acids or esters in an organic solvent which remains in the liquid state below the temperature at which DHA precipitates therefrom;
(6) gradually cooling and removing any new solid or liquid phases which separate from the solution during the cooling process;
and
(7) retaining the phase containing substantially pure DNA.

5 more elements

Dependencies are inferred from the claim text.