METHOD OF ISOLATING LIPIDS FROM A LYSED LIPIDS CONTAINING BIOMASS BY EMULSION INVERSION

Abstract

The current invention relates to a method of separating lipids from a lipids containing biomass by demulsification under mild conditions, to an oil and to a delipidated biomass as obtained by such a method.

Claims

1-15. (canceled)

16. A method of isolating a lipid from a lipid containing biomass, comprising the following steps: a) providing an aqueous suspension of a biomass comprising cells which contain the lipid; b) optionally lysing the cells of the biomass; c) concentrating the suspension until the volume ratio between oil and water in the suspension exceeds the value of 1; d) separating the oil containing light phase from the aqueous phase.

17. The method of claim 16, wherein the suspension is concentrated to a total dry matter (TDM) content of more than 60 wt.-%.

18. The method of claim 16, wherein the suspension is concentrated to a total dry matter (TDM) content of of between 65 and 80 wt.-%.

19. The method of claim 16, wherein concentration of the suspension is carried out by evaporation of water at a temperature not higher than 100° C.

20. The method of claim 16, wherein concentration of the suspension is carried out by evaporation of water at a temperature of between 70° C. and 100° C.

21. The method of claim 16, wherein cells of the biomass are lysed enzymatically, mechanically, chemically and/or physically.

22. The method of claim 16, wherein the suspension is provided as a fermentation broth with a biomass density of at least 80 g/l.

23. The method of claim 16, wherein the suspension is provided as a fermentation broth and/or with a biomass density of 160 g/l to 200 g/l.

24. The method of claim 16, wherein the cells of the biomass comprise an average of at least 10 wt.-% of lipids.

25. The method of claim 16, wherein the cells of the biomass comprise an average of at least 40 wt.-% of lipids.

26. The method of claim 16, wherein the cells which contain lipids comprise PUFAs containing lipid and are selected from algae, fungi, protists, bacteria, microalgae, plant cells, and mixtures thereof.

27. The method of claim 26, wherein the cells are from the family of Thraustochytrids.

28. The method of claim 16, wherein the method is carried out, without the addition of solvents or caustics.

29. The method of claim 16, wherein the method is carried out without the addition of any solvents, caustic soda or sodium hydroxide.

30. The method of claim 16, wherein the pH is kept below 9, during the complete process.

31. The method of claim 16, wherein the pH is kept between 4.5 and 8.5, during the complete process.

32. An oil, comprising fatty acid esters, in an amount of at least 50 wt.-%, and free atty acids (FFAs) in an amount of less than 0.6 wt.-%.

33. The oil of claim 32, wherein said oil comprises triacylglycerols (TAGs) in an amount of at least 50 wt.-%, and comprises polymerized TAGs in an amount of less than 1.0 wt.-%.

34. A delipidated biomass comprising less than 30 wt.-% of salts and/or ashes, less than 2 wt.-%, of a non-polar organic solvent and less than 0.5 wt.-%, of chloride, wherein the biomass preferably contains cells and/or cell debris of the Schizochytrium.

Description

WORKING EXAMPLES

Example 1

[0129] An unwashed cell broth containing microbial cells (Schizochytrium sp.) at a biomass density of over 100 g/l was heated to 60° C. in an agitated vessel. After heating up the suspension, the pH was adjusted to 7.5 by using caustic soda (50 wt.-% NaOH solution), before an alcalase (Alcalase® 2.4 FG (Novozymes)) was added in liquid form in an amount of 0.5 wt.-% (by weight broth). Stirring was continued for 3 hours at 60° C. After that, 1 kg samples of the lysed cell mixture were subsequently transferred into a rotation evaporator and heated to a temperature of 85° C. The different samples were concentrated in the rotation evaporator, until a total dry matter content of between 42 and 95 wt.-% was reached. After that stirring was continued for about one further hour at room temperature. Surprisingly the formation of two phases, an oil phase and an aqueous phase could be observed at a total dry matter content of more than 60 wt.-%. The oil phase could be directly separated from the aqueous phase by centrifugation. Centrifugation was carried out for 5 minutes at 12.000 g, if not indicated otherwise.

[0130] In the following tables the influence of different parameters on the yield of oil is disclosed.

TABLE-US-00001 TABLE 1 Influence of concentration on phase separation and oil yield Total Dry Amount of Free fatty Matter Phase isolated oil acids [wt.-%] separation [wt.-%] [wt.-%] 42.0 no — — 45.2 no — — 60 no — — 63 yes 85.3 0.4 72.6 yes 85.1 0.5 74.6 yes 85.3 0.4 79 yes 80.0 0.4 95 yes not det. not det.

[0131] As can be seen from table 1, an efficient phase separation, i.e. demulsification, takes place at a total dry matter content in the suspension of more than 60 wt.-%, leading to a yield of isolated oil of at least 80 wt.-%, wherein the oil contains only a relatively low amount of free fatty acids of not more than 0.5 wt.-%.

TABLE-US-00002 TABLE 2 Influence of mechanical measure on oil yield Total Dry Centrifugal Amount of Free fatty Matter force isolated oil acids [wt.-%] [g] [wt.-%] [wt.-%] 79.2 4000 80.0 0.4 73.8 4000 79.9 not det. 73.8 12000 88.0 not det.

[0132] As can be seen from table 2, the yield is improved, when a higher centrifugal force is applied. Centrifugation was carried out for 5 minutes, respectively.

TABLE-US-00003 TABLE 3 Influence of pH value on oil yield Total Dry Amount of Free fatty Polymerized Matter pH isolated oil acids Ash TAG [wt.-%] value [wt.-%] [wt.-%] [wt.-%] [wt.-%] 75.7 5 80.1 0.3 17 not det. 73.4 7 82.4 0.25 27 not det. 72.3 9 79.8 0.2 30 0.56

[0133] As can be seen from table 3, adjusting the pH value before carrying out the demulsification has no big influence on the oil yield, but using a lysed fermentation broth in the demulsification without addition of caustics results in a suspension with a relatively low content of ashes of less than 20 wt.-%. Further it can be learnt, that independent of the pH value very low contents of free fatty acids—as low as 0.2 wt.-%—can be realized by the methods according to the invention.—Furthermore it was found out that the methods according to the invention lead to products with a very low amount of polymerized TAGs.