Deaeration process

Abstract

A process for producing an oil, or a polyunsaturated fatty acid (PUFA), is described where an aqueous liquid comprising cells is deaerated, and the oil or PUFA is obtained from the cells. Deaeration can be performed by a wide variety of techniques, including the application of a vacuum (or reduced pressure), mechanical deaeration or degassing by reduced stirring or subjecting the broth to centrifugal forces, reducing viscosity (by dilution or heating), reduction in the supply of oxygen or air during fermentation or a reduction in stirring rate, lowering the pH (to lower the solubility of CO 2 ), filtration using PTFE capillaries, gas displacement (by bubbling in nitrogen or helium) or chemical deaeration (using oxygen scavengers).

1 . A process for producing an oil comprising at least 35% of a desired C20 or C22 polyunsaturated fatty acid (PUFA) and having an anisidine value of less than 20, the process comprising:
 (a) deaerating an aqueous liquid comprising microbial cells; and   (b) obtaining the oil from the microbial cells.   
     
     
         2 . A process according to  claim 1 , wherein the cells are heated or pasteurized after deaeration in (a) but before stage (b). 
     
     
         3 . A process according to  claim 1 , wherein the aqueous liquid is a fermentation broth. 
     
     
         4 . A process according to  claim 1 , which further comprises:
 (c) extracting, purifying or isolating the oil.   
     
     
         5 . A process according to  claim 1 , wherein deaeration comprises at least one method selected from:
 a) application of vacuum or reduced pressure;   b) mechanical deaeration/de-gassing by stirring, vibration, or use of an accelerative or g-force;   c) viscosity change by dilution with a liquid, or by increase in temperature;   d) change in fermentation conditions by a reduction during fermentation in at least one of airlift, air sparging, oxygen supply, air supply, or stirring rate;   e) pH change;   f) filtration;   g) gas displacement, with an inert gas;   h) chemical deaeration; and   i) time, wherein the aqueous liquid is allowed to rest under conditions such that oxygen or air diffuses out of the liquid.   
     
     
         6 . A process according to  claim 1  wherein the deaeration is effected by reduced stirring and/or gas displacement. 
     
     
         7 . A process according to  claim 6  wherein gas displacement is performed using a gas comprising either no oxygen or oxygen at a concentration level below atmospheric air. 
     
     
         8 . A process according to  claim 7  wherein the gas is, or comprises, nitrogen. 
     
     
         9 . A process according to  claim 1  wherein deaeration comprises subjecting the aqueous liquid to reduced pressure. 
     
     
         10 . A process according to  claim 9 , wherein said reduced pressure is a pressure of no more than 800 mbara. 
     
     
         11 . A process according to  claim 9 , wherein the aqueous liquid is deaerated using a vacuum or degassing pump, a parasol deaerator or an umbrella nozzle. 
     
     
         12 . A process according to  claim 1 , wherein deaeration results in a concentration of dissolved oxygen of less than 10 ppm. 
     
     
         13 . A process according to  claim 12 , wherein deaeration results in a concentration of dissolved oxygen of less than 5 ppm. 
     
     
         14 . A process according to  claim 13 , wherein deaeration results in a concentration of dissolved oxygen of less than 2 ppm. 
     
     
         15 . A process according to  claim 1 , wherein the process comprises subjecting the deaerated aqueous liquid to a temperature above 60° C. 
     
     
         16 . A process according to  claim 1 , wherein the cells are heated or pasteurised at a temperature above 80° C. 
     
     
         17 . A process according to  claim 1  wherein the desired PUFA is a C20 or C22Ω-3 or Ω-6 PUFA. 
     
     
         18 . A process according to  claim 17 , wherein the desired PUFA is arachidonic acid (ARA). 
     
     
         19 . A process according to  claim 17 , wherein the desired PUFA is docosahexaenoic acid (DHA). 
     
     
         20 . A process according to  claim 17 , wherein the desired PUFA is eicosapentaenoic acid (EPA). 
     
     
         21 . A process according to  claim 17 , wherein the desired PUFA is dihomo-γ-linolenic acid (DGLA). 
     
     
         22 . A process according to  claim 18 , wherein the cells are  Mortierella alpina  cells. 
     
     
         23 . A process according to  claim 19 , wherein the cells are  Crypthecodinium  cells. 
     
     
         24 . A process according to  claim 19 , wherein the cells are  Thraustochytrium  cells. 
     
     
         25 . A process according to  claim 1 , wherein the cells are yeast, bacterial, fungal or algal cells. 
     
     
         26 . A process according to  claim 1 , wherein the oil is a microbial oil. 
     
     
         27 . A process according to  claim 3 , wherein the cells are heated or pasteurized after deaeration in (a) but before stage (b), and deaerating results in a concentration of dissolved oxygen of less than 10 ppm. 
     
     
         28 . A process according to  claim 27 , wherein deaerating results in a concentration of dissolved oxygen of less than 5 ppm. 
     
     
         29 . A process according to  claim 18 , wherein the aqueous liquid is a fermentation broth, the cells are heated or pasteurized after deaeration in (a) but before stage (b), and deaerating results in a concentration of dissolved oxygen of less than 10 ppm. 
     
     
         30 . A process according to  claim 29 , wherein deaerating results in a concentration of dissolved oxygen of less than 5 ppm. 
     
     
         31 . A process according to  claim 19 , wherein the aqueous liquid is a fermentation broth, the cells are heated or pasteurized after deaeration in (a) but before stage (b), and deaerating results in a concentration of dissolved oxygen of less than 10 ppm. 
     
     
         32 . A process according to  claim 31 , wherein deaerating results in a concentration of dissolved oxygen of less than 5 ppm. 
     
     
         33 . A process according to  claim 1 , wherein the oil has an anisidine value of less than 15. 
     
     
         34 . A process according to  claim 33 , wherein the oil has an anisidine value of less than 10. 
     
     
         35 . A process according to  claim 1 , wherein the oil comprises at least 40% of a desired C20 or C22 polyunsaturated fatty acid (PUFA). 
     
     
         36 . An oil obtained by a process according to  claim 1 . 
     
     
         37 . A process for producing an oil comprising at least 35% of a desired C20 or C22 polyunsaturated fatty acid (PUFA), the process comprising:
 (a) deaerating an aqueous liquid comprising microbial cells, resulting in a concentration of dissolved oxygen of less than 10 ppm; and   (b) obtaining the oil from the microbial cells.   
     
     
         38 . A process according to  claim 37 , wherein the cells are heated or pasteurized after deaeration in (a) but before stage (b). 
     
     
         39 . A process according to  claim 37 , wherein the aqueous liquid is a fermentation broth. 
     
     
         40 . A process according to  claim 37 , which further comprises:
 (c) extracting, purifying or isolating the oil.   
     
     
         41 . A process according to  claim 37 , wherein deaeration comprises at least one method selected from:
 a) application of vacuum or reduced pressure;   b) mechanical deaeration/de-gassing by stirring, vibration, or use of an accelerative or g-force;   c) viscosity change by dilution with a liquid, or by increase in temperature;   d) change in fermentation conditions by a reduction during fermentation in at least one of airlift, air sparging, oxygen supply, air supply, or stirring rate;   e) pH change;   f) filtration;   g) gas displacement, with an inert gas;   h) chemical deaeration; and   i) time, wherein the aqueous liquid is allowed to rest under conditions such that oxygen or air diffuses out of the liquid.   
     
     
         42 . A process according to  claim 37  wherein the deaeration is effected by reduced stirring and/or gas displacement. 
     
     
         43 . A process according to  claim 42  wherein gas displacement is performed using a gas comprising either no oxygen or oxygen at a concentration level below atmospheric air. 
     
     
         44 . A process according to  claim 42  wherein the gas is, or comprises, nitrogen. 
     
     
         45 . A process according to  claim 37  wherein deaeration comprises subjecting the aqueous liquid to reduced pressure. 
     
     
         46 . A process according to  claim 45 , wherein said reduced pressure is a pressure of no more than 800 mbara. 
     
     
         47 . A process according to  claim 45 , wherein the aqueous liquid is deaerated using a vacuum or degassing pump, a parasol deaerator or an umbrella nozzle. 
     
     
         48 . A process according to  claim 37 , wherein deaeration results in a concentration of dissolved oxygen of less than 5 ppm. 
     
     
         49 . A process according to  claim 48 , wherein deaeration results in a concentration of dissolved oxygen of less than 2 ppm. 
     
     
         50 . A process according to  claim 37 , wherein the process comprises subjecting the deaerated aqueous liquid to a temperature above 60° C. 
     
     
         51 . A process according to  claim 37 , wherein the cells are heated or pasteurised at a temperature above 80° C. 
     
     
         52 . A process according to  claim 37  wherein the desired PUFA is a C20 or C22Ω-3 or Ω-6 PUFA. 
     
     
         53 . A process according to  claim 52 , wherein the desired PUFA is arachidonic acid (ARA). 
     
     
         54 . A process according to  claim 52 , wherein the desired PUFA is docosahexaenoic acid (DHA). 
     
     
         55 . A process according to  claim 52 , wherein the desired PUFA is eicosapentaenoic acid (EPA). 
     
     
         56 . A process according to  claim 52 , wherein the desired PUFA is dihomo-γ-linolenic acid (DGLA). 
     
     
         57 . A process according to  claim 53 , wherein the cells are  Mortierella alpina  cells. 
     
     
         58 . A process according to  claim 54 , wherein the cells are  Crypthecodinium  cells. 
     
     
         59 . A process according to  claim 54 , wherein the cells are  Thraustochytrium  cells. 
     
     
         60 . A process according to  claim 37 , wherein the cells are yeast, bacterial, fungal or algal cells. 
     
     
         61 . A process according to  claim 37 , wherein the oil is a microbial oil. 
     
     
         62 . A process according to  claim 53 , wherein deaerating results in a concentration of dissolved oxygen of less than 5 ppm. 
     
     
         63 . A process according to  claim 62 , wherein deaerating results in a concentration of dissolved oxygen of less than 2 ppm. 
     
     
         64 . A process according to  claim 37 , wherein the oil comprises at least 40% of a desired C20 or C22 polyunsaturated fatty acid (PUFA). 
     
     
         65 . An oil obtained by a process according to  claim 37 . 
     
     
         66 . A process for producing an oil comprising at least 35% of a desired C20 or C22 polyunsaturated fatty acid (PUFA), the process comprising:
 (a) deaerating an aqueous liquid comprising microbial cells; and   (b) obtaining the oil from the microbial cells, wherein   the cells are heated or pasteurised after deaeration in (a) but before stage (b).   
     
     
         67 . A process according to  claim 66 , wherein the aqueous liquid is a fermentation broth. 
     
     
         68 . A process according to  claim 66 , which further comprises:
 (c) extracting, purifying or isolating the oil.   
     
     
         69 . A process according to  claim 66 , wherein deaeration comprises at least one method selected from:
 a) application of vacuum or reduced pressure;   b) mechanical deaeration/de-gassing by stirring, vibration, or use of an accelerative or g-force;   c) viscosity change by dilution with a liquid, or by increase in temperature;   d) change in fermentation conditions by a reduction during fermentation in at least one of airlift, air sparging, oxygen supply, air supply, or stirring rate;   e) pH change;   f) filtration;   g) gas displacement, with an inert gas;   h) chemical deaeration; and   i) time, wherein the aqueous liquid is allowed to rest under conditions such that oxygen or air diffuses out of the liquid.   
     
     
         70 . A process according to  claim 66 , wherein the deaeration is effected by reduced stirring and/or gas displacement. 
     
     
         71 . A process according to  claim 70 , wherein gas displacement is performed using a gas comprising either no oxygen or oxygen at a concentration level below atmospheric air. 
     
     
         72 . A process according to  claim 70  wherein the gas is, or comprises, nitrogen. 
     
     
         73 . A process according to  claim 66  wherein deaeration comprises subjecting the aqueous liquid to reduced pressure. 
     
     
         74 . A process according to  claim 73 , wherein said reduced pressure is a pressure of no more than 800 mbara. 
     
     
         75 . A process according to  claim 74 , wherein the aqueous liquid is deaerated using a vacuum or degassing pump, a parasol deaerator or an umbrella nozzle. 
     
     
         76 . A process according to  claim 66 , wherein deaeration results in a concentration of dissolved oxygen of less than 10 ppm. 
     
     
         77 . A process according to  claim 76 , wherein deaeration results in a concentration of dissolved oxygen of less than 5 ppm. 
     
     
         78 . A process according to  claim 77 , wherein deaeration results in a concentration of dissolved oxygen of less than 2 ppm. 
     
     
         79 . A process according to  claim 78 , wherein the process comprises subjecting the deaerated aqueous liquid to a temperature above 60° C. 
     
     
         80 . A process according to  claim 66 , wherein the cells are heated or pasteurised at a temperature above 80° C. 
     
     
         81 . A process according to  claim 66 , wherein the desired PUFA is a C20 or C22Ω-3 or Ω-6 PUFA. 
     
     
         82 . A process according to  claim 81 , wherein the desired PUFA is arachidonic acid (ARA). 
     
     
         83 . A process according to  claim 81 , wherein the desired PUFA is docosahexaenoic acid (DHA). 
     
     
         84 . A process according to  claim 81 , wherein the desired PUFA is eicosapentaenoic acid (EPA). 
     
     
         85 . A process according to  claim 81 , wherein the desired PUFA is dihomo-γ-linolenic acid (DGLA). 
     
     
         86 . A process according to  claim 82 , wherein the cells are  Mortierella alpina  cells. 
     
     
         87 . A process according to  claim 83 , wherein the cells are  Crypthecodinium  cells. 
     
     
         88 . A process according to  claim 83 , wherein the cells are  Thraustochytrium  cells. 
     
     
         89 . A process according to  claim 66 , wherein the cells are yeast, bacterial, fungal or algal cells. 
     
     
         90 . A process according to  claim 66 , wherein the oil is a microbial oil. 
     
     
         91 . A process according to  claim 66 , wherein the oil comprises at least 40% of a desired C20 or C22 polyunsaturated fatty acid (PUFA). 
     
     
         92 . An oil obtained by a process according to  claim 66 .