Solventless extraction process

Abstract

The present invention provides a method for extracting lipids from microorganisms without using organic solvent as an extraction solvent. In particular, the present invention provides a method for extracting lipids from microorganisms by lysing cells and removing water soluble compound and/or materials by washing the lysed cell mixtures with aqueous washing solutions until a substantially non-emulsified lipid is obtained.

1 . A process for obtaining lipid from microorganisms comprising:
 (a) growing microorganisms in a culture medium;   (b) treating said culture medium and cells of the microorganism to release intracellular lipids by lysing or rupturing the cells, wherein the lysing or rupturing the cells comprises heating the cells to at least 50° C.;   (c) subjecting the culture medium containing the released intracellular lipids to gravity separation to form a light lipid-containing phase and a heavy phase;   (d) separating said heavy phase from said light phase; and   (e) obtaining said lipid from said light phase.   
     
     
         2 . (canceled) 
     
     
         3 . The process of  claim 1 , wherein said light phase comprises an emulsified lipid. 
     
     
         4 . The process of  claim 3  further comprising:
 (f) adding an aqueous extraction solution to said light phase of step (d); and 
 (g) repeating said steps (d) and (f) until said lipid becomes substantially non-emulsified prior to step (e). 
 
     
     
         5 . The process of  claim 3 , wherein said emulsified lipid comprises a suspension of said lipid in an aqueous solution. 
     
     
         6 . The process of  claim 1 , wherein said heavy phase comprises an aqueous solution. 
     
     
         7 . The process of  claim 1 , wherein said microorganisms are obtained from a fermentation process. 
     
     
         8 . The process of  claim 7  further comprising adding a base to a fermentation broth. 
     
     
         9 . The process of  claim 8 , wherein said base is selected from the group consisting of hydroxides, carbonates, bicarbonates, phosphates, and mixtures thereof. 
     
     
         10 . The process of  claim 7  further comprising solubilizing at least part of proteinaceous compounds in a fermentation broth. 
     
     
         11 . The process of  claim 1 , wherein said step Walt) further comprises exposing the cells to basic conditions, a chelating compound or mixtures thereof. 
     
     
         12 . The process of  claim 1 , wherein said microorganism is capable of growth at salinity level of less than about 12 g/L of sodium chloride. 
     
     
         13 . The process of  claim 1 , wherein said microorganism comprises at least about 20% by weight of lipid. 
     
     
         14 . The process of  claim 1 , wherein said microorganism is selected from the group consisting of algae, fungi, bacteria and protists. 
     
     
         15 . The process of  claim 14 , wherein said microorganisms comprise microorganisms of the order Thraustochytriales. 
     
     
         16 . The process of  claim 15 , wherein said microorganisms are selected from the genus  Thraustochytrium, Schizochytrium  and mixtures thereof. 
     
     
         17 . The process of  claim 16 , wherein said microorganisms are selected from the group consisting of microorganisms having the identifying characteristics of ATCC number 20888, ATCC number 20889, ATCC number 20890, ATCC number 20891 and ATCC number 20892, strains of  Mortierella schmuckeri , strains of  Crypthecodinium cohnii , mutant strains derived from any of the foregoing, and mixtures thereof. 
     
     
         18 . The process of  claim 1 , wherein said microorganisms are capable of producing at least about 0.1 grams per liter per hour of docosahexaenoic acid eicosapentaenoic acid, docosapentaenoic acid, arachidonic acid, stearidonic acid, dihomogammalinolenic acid and gamma-linolenic acid or mixtures thereof. 
     
     
         19 . The process of  claim 1 , wherein at least about 30% of said lipid is docosahexaenoic acid, eicosapentaenoic acid, docosapentaenoic acid, arachidonic acid, stearidonic acid, dihomogammalinolenic acid and gamma-linolenic acid or mixtures thereof. 
     
     
         20 - 46 . (canceled) 
     
     
         47 . The process of  claim 6 , wherein said aqueous solution comprises solid cell materials. 
     
     
         48 . A process for obtaining lipids from microorganisms comprising:
 (a) growing microorganisms in a culture medium;   (b) treating said culture medium and the cells of the microorganism to release intracellular lipids by lysing or rupturing the cells, wherein the lysing or rupturing the cells comprises heating the cells to at least 50° C.;   (c) subjecting the culture medium containing the released intracellular lipids to gravity separation to form a light lipid-containing phase and a heavy phase;   (d) separating said light phase from said heavy phase;   (e) treating said light phase to break an emulsion formed between said lipid and water; and   (f) recovering a crude lipid.   
     
     
         49 . The process of  claim 48  wherein said microorganisms are lipid-rich microorganisms. 
     
     
         50 . The process of  claim 48  wherein said microorganisms are selected from the group consisting of algae, bacteria, fungi and protists. 
     
     
         51 . The process of  claim 48  wherein said microorganisms are selected from the group consisting of golden algae, green algae, dinoflagellates, yeast, fungi of the genus  Mortierella , and Stramenopiles. 
     
     
         52 . The process of  claim 48 , wherein said microorganisms comprise microorganisms of the order Thraustochytriales. 
     
     
         53 . The process of  claim 52 , wherein said microorganisms are selected from the genus  Thraustochytrium, Schizochytrium  and mixtures thereof. 
     
     
         54 . The process of  claim 53 , wherein said microorganisms are selected from the group consisting of microorganisms having the identifying characteristics of ATCC number 20888, ATCC number 20889, ATCC number 20890, ATCC number 20891 and ATCC number 20892, strains of  Mortierella schmuckeri , strains of  Crypthecodinium cohnii , mutant strains derived from any of the foregoing, and mixtures thereof. 
     
     
         55 . The process of  claim 48 , wherein said microorganisms are capable of producing at least about 0.1 grams per liter per hour of docosahexaenoic acid, eicosapentaenoic acid, docosapentaenoic acid, arachidonic acid, stearidonic acid, dihomogammalinolenic acid and gamma-linolenic acid or mixtures thereof. 
     
     
         56 . The process of  claim 55 , wherein at least about 20% of said lipid is docosahexaenoic acid, eicosapentaenoic acid, docosapentaenoic acid, arachidonic acid, stearidonic acid, dihomogammalinolenic acid and gamma-linolenic acid or mixtures thereof. 
     
     
         57 . The process of  claim 48 , wherein step (b) further comprises exposing said cells to a basic compound, a chelating compound or combinations thereof. 
     
     
         58 . The process of  claim 57 , wherein step (b) comprises heating the cells to at least 50° C. before, during or after exposing the cells to a basic compound, a chelating compound or mixtures thereof. 
     
     
         59 . The process of  claim 48 , wherein said gravity separation of step (c) comprises passing the culture medium containing the released intracellular lipids through a stacked-disc, separator or decanter centrifuge. 
     
     
         60 . The process of  claim 48 , wherein the treatment of step to break the emulsion comprises mixing the emulsion with water, alcohol and/or acetone and subjecting the mixture to gravity separation. 
     
     
         61 . The process of  claim 60 , wherein said gravity separation comprises centrifugation. 
     
     
         62 . The process of  claim 61 , wherein said centrifugation includes treatment in a stacked-disc-, separator- or decanter-type centrifuge. 
     
     
         63 . The process of  claim 60 , wherein said treatment is repeated at least 3 times to obtain said crude lipid. 
     
     
         64 . The process of  claim 48 , wherein said crude lipid is subjected to further refining or processing to obtain a refined lipid. 
     
     
         65 . The process of  claim 64  wherein said crude lipid is bleached and deodorized.